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Malnutrition
Malnutrition
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Malnutrition
Underfed child in Dolo Ado, Ethiopia, at an MSF treatment tent
SpecialtyCritical care medicine
SymptomsProblems with physical or mental development; poor energy levels; hair loss; swollen legs and abdomen[1][2]
CausesEating a diet with too few or too many nutrients; malabsorption[3][4]
Risk factorsLack of breastfeeding; gastroenteritis; pneumonia; malaria; measles; poverty; homelessness[5]
PreventionImproving agricultural practices; reducing poverty; improving sanitation; education
TreatmentImproved nutrition; supplementation; ready-to-use therapeutic foods; treating the underlying cause[6][7][8]
MedicationEating food with enough nutrients on a near daily basis
Frequency673 million undernourished / 8.2% of the population (2024)[9]
Deaths406,000 from nutritional deficiencies (2015)[10]

Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems.[11][12] Specifically, it is a deficiency, excess, or imbalance of energy, protein and other nutrients which adversely affects the body's tissues and form.[13]

Malnutrition is a category of diseases that includes undernutrition and overnutrition.[14] Undernutrition is a lack of nutrients, which can result in stunted growth, wasting, and being underweight.[15] A surplus of nutrients causes overnutrition, which can result in obesity or toxic levels of micronutrients. In some developing countries, overnutrition in the form of obesity is beginning to appear within the same communities as undernutrition.[16]

Most clinical studies use the term 'malnutrition' to refer to undernutrition. However, the use of 'malnutrition' instead of 'undernutrition' makes it impossible to distinguish between undernutrition and overnutrition, a less acknowledged form of malnutrition.[13][17] Accordingly, a 2019 report by The Lancet Commission suggested expanding the definition of malnutrition to include "all its forms, including obesity, undernutrition, and other dietary risks."[18] The World Health Organization[19] and The Lancet Commission have also identified "[t]he double burden of malnutrition", which occurs from "the coexistence of overnutrition (overweight and obesity) alongside undernutrition (stunted growth and wasting)."[20][21]

Prevalence

[edit]
Number of people undernourished by region

It was estimated in 2017 that nearly one in three persons globally had at least one form of malnutrition: wasting, stunting, vitamin or mineral deficiency, overweight, obesity, or diet-related noncommunicable diseases.[22] Undernutrition is more common in developing countries.[23] Stunting is more prevalent in urban slums than in rural areas.[24]

Studies on malnutrition have the population categorised into different groups including infants, under-five children, children, adolescents, pregnant women, adults and the elderly population. The use of different growth references in different studies leads to variances in the undernutrition prevalence reported in different studies. Some of the growth references used in studies include the National Center for Health Statistics (NCHS) growth charts, WHO reference 2007, Centers for Disease Control and Prevention (CDC) growth charts, National Health and Nutrition Examination Survey (NHANES), WHO reference 1995, Obesity Task Force (IOTF) criteria and Indian Academy of Pediatrics (IAP) growth charts.[25] In 2023, an estimated 28.9 percent of the global population – 2.33 billion people – were moderately or severely food insecure.[26]

In children

[edit]

The prevalence of undernutrition is highest among children under five.[24] In 2021, 148.1 million children under five years old were stunted, 45 million were wasted, and 37 million were overweight or obese.[27] The same year, an estimated 45% of deaths in children were linked to undernutrition.[27][5] As of 2020, the prevalence of wasting among children under five in South Asia was reported to be 16% moderately or severely wasted.[24] As of 2022, UNICEF reported this prevalence as having slightly improved, but still being at 14.8%.[28] India has one of the highest burdens of wasting in Asia with over 20% wasted children.[29] However, the burden of undernutrition among under-five children in African countries is much higher. A pooled analysis of the prevalence of chronic undernutrition among under-five children in East Africa was identified to be 33.3%. This prevalence of undernutrition among under-five children ranged from 21.9% in Kenya to 53% in Burundi.[30]

In Tanzania, the prevalence of stunting, among children under five varied from 41% in lowland and 64.5% in highland areas. Undernutrition by underweight and wasting was 11.5% and 2.5% in lowland and 22.% and 1.4% in the highland areas of Tanzania respectively.[31] In South Sudan, the prevalence of undernutrition explained by stunting, underweight and wasting in under-five children were 23.8%, 4.8% and 2.3% respectively.[32] In 28 countries, at least 30% of children were still affected by stunting in 2022.[33]

Vitamin A deficiency affects one third of children under age 5 around the world,[34] leading to 670,000 deaths and 250,000–500,000 cases of blindness.[35] Vitamin A supplementation has been shown to reduce all-cause mortality by 12 to 24%.[36]

In adults

[edit]

As of June 2021, 1.9 billion adults were overweight or obese, and 462 million adults were underweight.[27] Globally, two billion people had iodine deficiency in 2017.[37] In 2020, 900 million women and children had anemia, which is often caused by iron deficiency.[38] More than 3.1 billion people in the world – 42% – were unable to afford a healthy diet in 2021.[39]

Certain groups have higher rates of undernutrition, including elderly people and women (in particular while pregnant or breastfeeding children under five years of age). Undernutrition is an increasing health problem in people aged over 65 years, even in developed countries, especially among nursing home residents and in acute care hospitals.[40] In the elderly, undernutrition is more commonly due to physical, psychological, and social factors, not a lack of food.[41] Age-related reduced dietary intake due to chewing and swallowing problems, sensory decline, depression, imbalanced gut microbiome, poverty and loneliness are major contributors to undernutrition in the elderly population. Malnutrition is also attributed due to wrong diet plan adopted by people who aim to reduce their weight without medical practitioners or nutritionist advice.[42]

Increase in 2020

[edit]
Four year old Palestinian girl starved to death, during Gaza Famine

There has been a global increase in food insecurity and hunger between 2011 and 2020. In 2015, 795 million people (about one in ten people on earth) had undernutrition.[43][44] It is estimated that between 691 and 783 million people in the world faced hunger in 2022.[45] According to UNICEF, 2.4 billion people were moderately or severely food insecure in 2022, 391 million more than in 2019.[46]

Projected numbers of undernourished people by FAO shows global malnutrition rates

These increases are partially related to the COVID-19 pandemic, which continues to highlight the weaknesses of current food and health systems. It has contributed to food insecurity, increasing hunger worldwide; meanwhile, lower physical activity during lockdowns has contributed to increases in overweight and obesity.[47] In 2020, experts estimated that by the end of the year, the pandemic could have double the number of people at risk of suffering acute hunger, around 130 million more undernourished people.[48][49] Similarly, experts estimated that the prevalence of moderate and severe wasting could increase by 14% due to COVID-19; coupled with reductions in nutrition and health services coverage, this could result in over 128,000 additional deaths among children under 5 in 2020 alone.[47] Although COVID-19 is less severe in children than in adults, the risk of severe disease increases with undernutrition.[50]

Other major causes of hunger include manmade conflicts, climate changes, and economic downturns.[51]

Type

[edit]
External videos
video icon Daniel Quinn on Facts of World Hunger

Undernutrition

[edit]
Prevalence of undernourishment (2020–2022 average)
Number of undernourished people (2020–2022 average)
The prevalence of undernourishment (PoU) was still higher in 2022 than before the pandemic in 58% of countries, and the situation is worse in low-income countries (77%).

Undernutrition can occur either due to protein-energy wasting or as a result of micronutrient deficiencies.[2][52][27][1][3][53][54] It adversely affects physical and mental functioning, and causes changes in body composition and body cell mass.[55][56] Undernutrition is a major health problem, causing the highest mortality rate in children, particularly in those under 5 years, and is responsible for long-lasting physiologic effects.[57] It is a barrier to the complete physical and mental development of children.[54]

Undernutrition can manifest as stunting, wasting, and underweight. If undernutrition occurs during pregnancy, or before two years of age, it may result in permanent problems with physical and mental development.[1][53] Extreme undernutrition can cause starvation, chronic hunger, Severe Acute Malnutrition (SAM), and/or Moderate Acute Malnutrition (MAM).

The signs and symptoms of micronutrient deficiencies depend on which micronutrient is lacking.[2] However, undernourished people are often thin and short, with very poor energy levels; and swelling in the legs and abdomen is also common.[1][2][53] People who are undernourished often get infections and frequently feel cold.[2]

Micronutrient undernutrition

[edit]

Micronutrient undernutrition results from insufficient intake of vitamins and minerals.[27] Worldwide, deficiencies in iodine, Vitamin A, and iron are the most common. Children and pregnant women in low-income countries are at especially high risk for micronutrient deficiencies.[27][53]

Anemia is most commonly caused by iron deficiency, but can also result from other micronutrient deficiencies and diseases. Vitamin B12 deficiency may cause anemia, but not in all cases, in which may result in changes in consciousness or thinking, or even irreversible neurological damage.[58] This condition can have major health consequences.[59]

It is possible to have overnutrition simultaneously with micronutrient deficiencies; this condition is termed the double burden of malnutrition.

Protein-energy malnutrition

[edit]

'Undernutrition' sometimes refers specifically to protein–energy malnutrition (PEM).[2][60] This condition involves both micronutrient deficiencies and an imbalance of protein intake and energy expenditure.[52] It differs from calorie restriction in that calorie restriction may not result in negative health effects. Hypoalimentation (underfeeding) is one cause of undernutrition.[61]

Two forms of PEM are kwashiorkor and marasmus; both commonly coexist.[11]

Child in the United States with signs of kwashiorkor, a dietary protein deficiency

Kwashiorkor is primarily caused by inadequate protein intake.[11] Its symptoms include edema, wasting, liver enlargement, hypoalbuminaemia, and steatosis; the condition may also cause depigmentation of skin and hair.[11] The disorder is further identified by a characteristic swelling of the belly, and extremities which disguises the patient's undernourished condition.[62] 'Kwashiorkor' means 'displaced child' and is derived from the Ga language of coastal Ghana in West Africa. It means "the sickness the baby gets when the next baby is born," as it often occurs when the older child is deprived of breastfeeding and weaned to a diet composed largely of carbohydrates.[63]

Marasmus (meaning 'to waste away') can result from a sustained diet that is deficient in both protein and energy. This causes their metabolism to adapt to prolong survival.[11] The primary symptoms are severe wasting, leaving little or no edema; minimal subcutaneous fat; and abnormal serum albumin levels.[11] It is traditionally seen in cases of famine, significant food restriction, or severe anorexia.[11] Conditions are characterized by extreme wasting of the muscles and a gaunt expression.[62]

Overnutrition

[edit]

Excessive consumption of energy-dense foods and drinks and limited physical activity causes overnutrition.[64] It causes overweight, defined as a body mass index (BMI) of 25 or more, and can lead to obesity (a BMI of 30 or more).[27][2] Obesity has become a major health issue worldwide.[65] Overnutrition is linked to chronic non-communicable diseases like diabetes, certain cancers, and cardiovascular diseases. Hence identifying and addressing the immediate risk factors has become a major health priority.[66] The recent evidence on the impact of diet-induced obesity in fathers and mothers around the time of conception is identified to negatively program the health outcomes of multiple generations.[67]

According to UNICEF, at least 1 in every 10 children under five is overweight in 33 countries.[68]

Classifying malnutrition

[edit]

Definition by Gomez and Galvan

[edit]

In 1956, Gómez and Galvan studied factors associated with death in a group of undernourished children in a hospital in Mexico City, Mexico. They defined three categories of malnutrition: first, second, and third degree.[69] The degree of malnutrition is calculated based on a child's body size compared to the median weight for their age.[70] The risk of death increases with increasing degrees of malnutrition.[69]

An adaptation of Gomez's original classification is still used today. While it provides a way to compare malnutrition within and between populations, this classification system has been criticized for being "arbitrary" and for not considering overweight as a form of malnutrition. Also, height alone may not be the best indicator of malnutrition; children who are born prematurely may be considered short for their age even if they have good nutrition.[71]

Degree of PEM % of desired body weight for age and sex
Normal 90–100%
Mild: Grade I (1st degree) 75–89%
Moderate: Grade II (2nd degree) 60–74%
Severe: Grade III (3rd degree) <60%
SOURCE:"Serum Total Protein and Albumin Levels in Different Grades of Protein Energy Malnutrition"[62]

Definition by Waterlow

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In the 1970s, John Conrad Waterlow established a new classification system for malnutrition.[72] Instead of using just weight for age measurements, Waterlow's system combines weight-for-height (indicating acute episodes of malnutrition) with height-for-age to show the stunting that results from chronic malnutrition.[73] One advantage of the Waterlow classification is that weight for height can be calculated even if a child's age is unknown.[72]

Degree of PEM Stunting (%) Height for age Wasting (%) Weight for height
Normal: Grade 0 >95% >90%
Mild: Grade I 87.5–95% 80–90%
Moderate: Grade II 80–87.5% 70–80%
Severe: Grade III <80% <70%
SOURCE: "Classification and definition of protein-calorie malnutrition." by Waterlow, 1972[72]

The World Health Organization frequently uses these classifications of malnutrition, with some modifications.[70]

Effects

[edit]
Child of a sharecropper with undernutrition and rickets, 1935

Undernutrition weakens every part of the immune system.[74] Protein and energy undernutrition increases susceptibility to infection; so do deficiencies of specific micronutrients (including iron, zinc, and vitamins).[74] In communities or areas that lack access to safe drinking water, these additional health risks present a critical problem.[citation needed]

Undernutrition plays a major role in the onset of active tuberculosis.[75] It also raises the risk of HIV transmission from mother to child, and increases replication of the virus.[74] Undernutrition can cause vitamin-deficiency-related diseases like scurvy and rickets. As undernutrition worsens, those affected have less energy and experience impairment in brain functions.[citation needed]

Undernutrition can also cause acute problems, like hypoglycemia (low blood sugar). This condition can cause lethargy, limpness, seizures, and loss of consciousness. Children are particularly at risk and can become hypoglycemic after 4 to 6 hours without food. Dehydration can also occur in malnourished people, and can be life-threatening, especially in babies and small children.[citation needed]

Signs

[edit]

There are many different signs of dehydration in undernourished people. These can include sunken eyes; a very dry mouth; decreased urine output and/or dark urine; increased heart rate with decreasing blood pressure; and altered mental status.

Site Sign
Face Moon face (in kwashiorkor); shrunken, monkey-like face (in marasmus)
Eye Dry eyes; pale conjunctiva; periorbital edema; Bitot's spots (in vitamin A deficiency)
Mouth Angular stomatitis; cheilitis; glossitis; parotid enlargement; spongy, bleeding gums (in vitamin C and B12 deficiencies)
Teeth Enamel mottling; delayed eruption
Hair Dull, sparse, brittle hair, with thinning of the hair follicles; hypopigmentation; flag sign (alternating bands of light and normal color); broomstick eyelashes; alopecia
Skin Dry skin; follicular hyperkeratosis; patchy hyper- and hypopigmentation; erosions; poor wound healing; loose and wrinkled skin (in marasmus); shiny and edematous skin (in kwashiorkor)
Nail Koilonychia; thin and soft nail plates; fissures or ridges
Musculature Muscle wasting, particularly in the buttocks and thighs
Skeletal Deformities, usually resulting from deficiencies in calcium, vitamin D, or vitamin C
Abdomen Distended; hepatomegaly with fatty liver; possible ascites
Cardiovascular Bradycardia; hypotension; reduced cardiac output; small vessel vasculopathy
Neurologic Global developmental delay; loss of knee and ankle reflexes; poor memory, often resulting from deficiencies in vitamin B12 and other B vitamins
Hematological Pallor; petechiae; bleeding diathesis
Behavior Lethargic; apathetic; anxious
Source: "Protein Energy Malnutrition"[70]

Cognitive development

[edit]

Protein-calorie malnutrition can cause cognitive impairments. This most commonly occurs in people who were malnourished during a "critical period ... from the final third of gestation to the first 2 years of life".[76] For example, in children under two years of age, iron deficiency anemia is likely to affect brain function acutely, and probably also chronically. Similarly, folate deficiency has been linked to neural tube defects.[77]

Iodine deficiency is "the most common preventable cause of mental impairment worldwide."[78][79] "Even moderate [iodine] deficiency, especially in pregnant women and infants, lowers intelligence by 10 to 15 I.Q. points, shaving incalculable potential off a nation's development."[78] Among those affected, very few people experience the most visible and severe effects: disabling goiters, cretinism and dwarfism. These effects occur most commonly in mountain villages. However, 16 percent of the world's people have at least mild goiter (a swollen thyroid gland in the neck)."[78][80]

Causes and risk factors

[edit]
Union Army soldier on his release from Confederate prison, around 1865

Social and political

[edit]
A child with extreme malnutrition

Social conditions have a significant influence on the health of people.[81] The social determinants of undernutrition mainly include poor education, poverty, disease burden and lack of women's empowerment.[82] Identifying and addressing these determinants can eliminate undernutrition in the long term.[82] Identification of the social conditions that causes malnutrition in children under five has received significant research attention as it is a major public health problem.[citation needed]

Undernutrition most commonly results from a lack of access to high-quality, nutritious food.[5] The household income is a socio-economic variable that influences the access to nutritious food and the probability of under and overnutrition in a community.[83] In the study by Ghattas et al. (2020), the probability of overnutrition is significantly higher in higher-income families than in disadvantaged families.[21] High food prices is a major factor preventing low income households from getting nutritious food[1][5] For example, Khan and Kraemer (2009) found that in Bangladesh, low socioeconomic status was associated with chronic malnutrition since it inhibited purchase of nutritious foods (like milk, meat, poultry, and fruits).[84]

Food shortages may also contribute to malnutritions in countries which lack technology. However, in the developing world, eighty percent of malnourished children live in countries that produce food surpluses, according to estimates from the Food and Agriculture Organization (FAO).[85] The economist Amartya Sen observes that, in recent decades, famine has always been a problem of food distribution, purchasing power, and/or poverty, since there has always been enough food for everyone in the world.[86]

There are also sociopolitical causes of malnutrition. For example, the population of a community might be at increased risk for malnutrition if government is poor and the area lacks health-related services. On a smaller scale, certain households or individuals may be at an even higher risk due to differences in income levels, access to land, or levels of education.[87] Community plays a crucial role in addressing the social causes of malnutrition.[88] For example, communities with high social support and knowledge sharing about social protection programs can enable better public service demands.[89] Better public service demands and social protection programs minimise the risk of malnutrition in these communities.

It is argued that commodity speculators are increasing the cost of food. As the real-estate bubble in the United States was collapsing, it is said that trillions of dollars moved to invest in food and primary commodities, causing the 2007–2008 food price crisis.[90]

The use of biofuels as a replacement for traditional fuels raises the price of food.[91] The United Nations special rapporteur on the right to food, Jean Ziegler proposes that agricultural waste, such as corn cobs and banana leaves, should be used as fuel instead of crops.[92]

In some developing countries, overnutrition (in the form of obesity) is beginning to appear in the same communities where malnutrition occurs.[93] Overnutrition increases with urbanisation, food commercialisation and technological developments and increases physical inactivity.[94] Variations in the health status of individuals in the same society are associated with the societal structure and an individual's socioeconomic status which leads to income inequality, racism, educational differences and lack of opportunities.[95]

Diseases and conditions

[edit]

Infectious diseases which increase nutrient requirements, such as gastroenteritis,[96] pneumonia, malaria, and measles, can cause malnutrition.[5] So can some chronic illnesses, especially HIV/AIDS.[97][98]

Malnutrition can also result from abnormal nutrient loss due to diarrhea or chronic small bowel illnesses, like Crohn's disease or untreated coeliac disease.[4][8][99] "Secondary malnutrition" can result from increased energy expenditure.[70][100]

In infants, a lack of breastfeeding may contribute to undernourishment.[70][100] Anorexia nervosa and bariatric surgery can also cause malnutrition.[101][102]

Dietary practices

[edit]

Undernutrition

[edit]

Undernutrition due to lack of adequate breastfeeding is associated with the deaths of an estimated one million children annually. Illegal advertising of breast-milk substitutes contributed to malnutrition and continued three decades after its 1981 prohibition under the WHO International Code of Marketing Breast Milk Substitutes.[103]

Maternal malnutrition can also factor into the poor health or death of a baby. Over 800,000 neonatal deaths have occurred because of deficient growth of the fetus in the mother's womb.[104]

Deriving too much of one's diet from a single source, such as eating almost exclusively potato, maize or rice, can cause malnutrition. This may either be from a lack of education about proper nutrition, only having access to a single food source, or from poor healthcare access and unhealthy environments.[105][106]

It is not just the total amount of calories that matters but specific nutritional deficiencies such as vitamin A deficiency, iron deficiency or zinc deficiency can also increase risk of death.[107]

Overnutrition

[edit]
Chart showing a trend between obesity and diabetes over the years

Overnutrition caused by overeating is also a form of malnutrition. In the United States, more than half of all adults are now overweight—a condition that, like hunger, increases susceptibility to disease and disability, reduces worker productivity, and lowers life expectancy.[85] Overeating is much more common in the United States, since most people have adequate access to food. Many parts of the world have access to a surplus of non-nutritious food. Increased sedentary lifestyles also contribute to overnutrition. Yale University psychologist Kelly Brownell calls this a "toxic food environment", where fat- and sugar-laden foods have taken precedence over healthy nutritious foods.[85]

In these developed countries, overnutrition can be prevented by choosing the right kind of food. More fast food is consumed per capita in the United States than in any other country. This mass consumption of fast food results from its affordability and accessibility. Fast food, which is low in cost and nutrition, is high in calories. Due to increasing urbanization and automation, people are living more sedentary lifestyles. These factors combine to make weight gain difficult to avoid.[108]

Overnutrition also occurs in developing countries. It has appeared in parts of developing countries where income is on the rise.[85] It is also a problem in countries where hunger and poverty persist. Economic development, rapid urbanisation and shifting dietary patterns have increased the burden of overnutrition in the cities of low and middle-income countries.[109] In China, consumption of high-fat foods has increased, while consumption of rice and other goods has decreased.[85] Overeating leads to many diseases, such as heart disease and diabetes, that may be fatal.

Agricultural productivity

[edit]
Most of the people unable to afford a healthy diet in 2021 lived in southern Asia, and in eastern and western Africa.

Local food shortages can be caused by a lack of arable land, adverse weather, and/or poorer farming skills (like inadequate crop rotation). They can also occur in areas which lack the technology or resources needed for the higher yields found in modern agriculture. These resources include fertilizers, pesticides, irrigation, machinery, and storage facilities. As a result of widespread poverty, farmers and governments cannot provide enough of these resources to improve local yields.[citation needed]

Additionally, the World Bank and some wealthy donor countries have pressured developing countries to use free market policies. Even as the United States and Europe extensively subsidized their own farmers, they urged developing countries to cut or eliminate subsidized agricultural inputs, like fertilizer.[110][111] Without subsidies, few (if any) farmers in developing countries can afford fertilizer at market prices. This leads to low agricultural production, low wages, and high, unaffordable food prices.[110] Fertilizer is also increasingly unavailable because Western environmental groups have fought to end its use due to environmental concerns. The Green Revolution pioneers Norman Borlaug and Keith Rosenberg cited as the obstacle to feeding Africa by .[112]

Future threats

[edit]

In the future, variety of factors could potentially disrupt global food supply and cause widespread malnutrition. According to UNICEF's projections, it is projected that almost 600 million people will be chronically undernourished in 2030.[113][114]

Global warming is of importance to food security. Almost all malnourished people (95%) live in the tropics and subtropics, where the climate is relatively stable. According to the Intergovernmental Panel on Climate Change report in 2007, temperature increases in these regions are "very likely."[115] Even small changes in temperatures can make extreme weather conditions occur more frequently.[115] Extreme weather events, like drought, have a major impact on agricultural production, and hence nutrition. For example, the 1998–2001 Central Asian drought killed about 80 percent of livestock in Iran and caused a 50% reduction in wheat and barley crops there.[116] Other central Asian nations experienced similar losses. An increase in extreme weather such as drought in regions such as Sub-Saharan Africa would have even greater consequences in terms of malnutrition. Even without an increase of extreme weather events, a simple increase in temperature reduces the productivity of many crop species, and decreases food security in these regions.[115][117]

Another threat is colony collapse disorder, a phenomenon where bees die in large numbers.[118] Since many agricultural crops worldwide are pollinated by bees, colony collapse disorder represents a threat to the global food supply.[119]

Prevention

[edit]
Irrigation canals have opened dry desert areas of Egypt to agriculture.

Reducing malnutrition is key part of the United Nations' Sustainable Development Goal 2 (SDG2), "Zero Hunger", which aims to reduce malnutrition, undernutrition, and stunted child growth.[120] Managing severe acute undernutrition in a community setting has received significant research attention.[82][54]

Food security

[edit]

In the 1950s and 1960s, the Green Revolution aimed to bring modern Western agricultural techniques (like nitrogen fertilizers and pesticides) to Asia. Investments in agriculture, such as fund fertilizers and seeds, increased food harvests and thus food production. Consequently, food prices and malnutrition decreased (as they had earlier in Western nations).[110][121]

The Green Revolution was possible in Asia because of existing infrastructure and institutions, such as a system of roads and public seed companies that made seeds available.[122] These resources were in short supply in Africa, decreasing the Green Revolution's impact on the continent.

For example, almost five million of the 13 million people in Malawi used to need emergency food aid. However, in the early 2000s, the Malawian government changed its agricultural policies, and implemented subsidies for fertilizer and seed introduced against World Bank strictures. By 2007, farmers were producing record-breaking corn harvests. Corn production leaped to 3.4 million in 2007 compared to 1.2 million in 2005, making Malawi a major food exporter.[110] Consequently, food prices lowered and wages for farmworkers rose.[110] Such investments in agriculture are still needed in other African countries like the Democratic Republic of the Congo (DRC). Despite the country's great agricultural potential, the prevalence of malnutrition in the DRC is among the highest in the world.[123] Proponents for investing in agriculture include Jeffrey Sachs, who argues that wealthy countries should invest in fertilizer and seed for Africa's farmers.[110][124]

Imported Ready to Use Therapeutic Food (RUTF) has been used to treat malnutrition in northern Nigeria. Some Nigerians also use soy kunu, a locally sourced and prepared blend consisting of peanut, millet and soybeans.[125]

New technology in agricultural production has great potential to combat undernutrition. It makes farming easier, thus improving agricultural yields.[126] By increasing farmers' incomes, this could reduce poverty. It would also open up area which farmers could use to diversify crops for household use.

The World Bank claims to be part of the solution to malnutrition, asserting that countries can best break the cycle of poverty and malnutrition by building export-led economies, which give them the financial means to buy foodstuffs on the world market.

Economics

[edit]

Many aid groups have found that giving cash assistance (or cash vouchers) is more effective than donating food. Particularly in areas where food is available but unaffordable, giving cash assistance is a cheaper, faster, and more efficient way to deliver help to the hungry.[127] In 2008, the UN's World Food Program, the biggest non-governmental distributor of food, announced that it would begin distributing cash and vouchers instead of food in some areas, which Josette Sheeran, the WFP's executive director, described as a "revolution" in food aid.[127][128] The aid agency Concern Worldwide piloted a method of giving cash assistance using a mobile phone operator, Safaricom, which runs a money transfer program that allows cash to be sent from one part of a country to another.[127]

However, during a drought, delivering food might be the most appropriate way to help people, especially those who live far from markets and thus have limited access to them.[127] Fred Cuny stated that "the chances of saving lives at the outset of a relief operation are greatly reduced when food is imported. By the time it arrives in the country and gets to people, many will have died."[129] U.S. law requires food aid to be purchased at home rather than in the countries where the hungry live; this is inefficient because approximately half of the money spent goes for transport.[130] Cuny further pointed out that "studies of every recent famine have shown that food was available in-country—though not always in the immediate food deficit area" and "even though by local standards the prices are too high for the poor to purchase it, it would usually be cheaper for a donor to buy the hoarded food at the inflated price than to import it from abroad."[131]

A soup kitchen in Montreal, Quebec, Canada in 1931

Food banks and soup kitchens address malnutrition in places where people lack money to buy food. A basic income has been proposed as a way to ensure that everyone has enough money to buy food and other basic needs. This is a form of social security in which all citizens or residents of a country regularly receive an unconditional sum of money, either from a government or some other public institution, in addition to any income received from elsewhere.[132]

Successful initiatives

[edit]

Ethiopia pioneered a program that later became part of the World Bank's prescribed method for coping with a food crisis. Through the country's main food assistance program, the Productive Safety Net Program, Ethiopia provided rural residents who were chronically short of food a chance to work for food or cash. Foreign aid organizations like the World Food Program were then able to buy food locally from surplus areas to distribute in areas with a shortage of food.[133] Aid organizations now view the Ethiopian program as a model of how to best help hungry nations.[citation needed]

Successful initiatives also include Brazil's recycling program for organic waste, which benefits farmers, the urban poor, and the city in general. City residents separate organic waste from their garbage, bag it, and then exchange it for fresh fruit and vegetables from local farmers. This reduces the country's waste while giving the urban poor a steady supply of nutritious food.[108]

World population

[edit]

Restricting population size is a proposed solution to malnutrition. Thomas Malthus argues that population growth can be controlled by natural disasters and by voluntary limits through "moral restraint."[134] Robert Chapman suggests that government policies are a necessary ingredient for curtailing global population growth.[135] The United Nations recognizes that poverty and malnutrition (as well as the environment) are interdependent and complementary with population growth.[136] According to the World Health Organization, "Family planning is key to slowing unsustainable population growth and the resulting negative impacts on the economy, environment, and national and regional development efforts".[137] However, more than 200 million women worldwide lack adequate access to family planning services.

There are different theories about what causes famine. Some theorists, like the Indian economist Amartya Sen, believe that the world has more than enough resources to sustain its population. In this view, malnutrition is caused by unequal distribution of resources and under- or unused arable land.[138][139] For example, Sen argues that "no matter how a famine is caused, methods of breaking it call for a large supply of food in the Public Distribution System. This applies not only to organizing rationing and control, but also to undertaking work programmes and other methods of increasing purchasing power for those hit by shifts in exchange entitlements in a general inflationary situation."[86]

Food sovereignty

[edit]

Food sovereignty is one suggested policy framework to resolve access issues. In this framework, people (rather than international market forces) have the right to define their own food, agricultural, livestock, and fishery systems. Food First is one of the primary think tanks working to build support for food sovereignty. Neoliberals advocate for an increasing role of the free market.[citation needed]

Health facilities

[edit]

Another possible long-term solution to malnutrition is to increase access to health facilities in rural parts of the world. These facilities could monitor undernourished children, act as supplemental food distribution centers, and provide education on dietary needs. Similar facilities have already proven very successful in countries such as Peru and Ghana.[140][141]

Breastfeeding

[edit]

In 2016, estimates suggested that more widespread breastfeeding could prevent about 823,000 deaths annually of children under age 5.[142] In addition to reducing infant deaths, breast milk provides an important source of micronutrients - which are clinically proven to bolster children's immune systems – and provides long-term defenses against non-communicable and allergic diseases.[143] Breastfeeding may improve cognitive abilities in children, and correlates strongly with individual educational achievements.[143][144] As previously noted, lack of proper breastfeeding is a major factor in child mortality rates, and is a primary determinant of disease development for children. The medical community recommends exclusively breastfeeding infants for 6 months, with nutritional whole food supplementation and continued breastfeeding up to 2 years or older for overall optimal health outcomes.[144][145][146] Exclusive breastfeeding is defined as giving an infant only breast milk for six months as a source of food and nutrition.[144][146] This means no other liquids, including water or semi-solid foods.[146]

Barriers to breastfeeding

[edit]

Breastfeeding is noted as one of the most cost-effective medical interventions benefiting child health.[145] While there are considerable differences among developed and developing countries, there are universal determinants of whether a mother breastfeeds or uses formula; these include income, employment, social norms, and access to healthcare.[144][145] Many newly made mothers face financial barriers; community-based healthcare workers have helped to alleviate these barriers, while also providing a viable alternative to traditional and expensive hospital-based medical care.[144] Recent studies, based upon surveys conducted from 1995 to 2010, show that exclusive breastfeeding rates have risen globally, from 33% to 39%.[146] Despite the growth rates, medical professionals acknowledge the need for improvement given the importance of exclusive breastfeeding.[146]

21st century global initiatives

[edit]

Starting around 2009, there was renewed international media and political attention focused on malnutrition. This resulted in part from spikes in food prices and the 2008 financial crisis. Additionally, there was an emerging consensus that combating malnutrition is one of the most cost-effective ways to contribute to development. This led to the 2010 launch of the UN's Scaling up Nutrition movement (SUN).[147]

In April 2012, a number of countries signed the Food Assistance Convention, the world's first legally binding international agreement on food aid. The following month, the Copenhagen Consensus recommended that politicians and private sector philanthropists should prioritize interventions against hunger and malnutrition to maximize the effectiveness of aid spending. The Consensus recommended prioritizing these interventions ahead of any others, including the fights against malaria and AIDS.[148]

In June 2015, the European Union and the Bill & Melinda Gates Foundation launched a partnership to combat undernutrition, especially in children. The program was first implemented in Bangladesh, Burundi, Ethiopia, Kenya, Laos and Niger. It aimed to help these countries improve information and analysis about nutrition, enabling them to develop effective national nutrition policies.[149]

Also in 2015, the UN's Food and Agriculture Organization created a partnership aimed at ending hunger in Africa by 2025. The African Union's Comprehensive Africa Agriculture Development Programme (CAADP) provided the framework for the partnership. It includes a variety of interventions, including support for improved food production, a strengthening of social protection, and integration of the right to food into national legislation.[150]

The EndingHunger campaign is an online communication campaign whose goal is to raise awareness about hunger. The campaign has created viral videos depicting celebrities voicing their anger about the large number of hungry people in the world.[citation needed]

After the Millennium Development Goals expired in 2015, the Sustainable Development Goals became the main global policy focus to reduce hunger and poverty. In particular, Goal 2: Zero Hunger sets globally agreed-upon targets to wipe out hunger, end all forms of malnutrition, and make agriculture sustainable.[151] The partnership Compact2025 develops and disseminates evidence-based advice to politicians and other decision-makers, with the goal of ending hunger and undernutrition by 2025.[152][153][154] The International Food Policy Research Institute (IFPRI) led the partnership, with the involvement of UN organisations, non-governmental organizations (NGOs), and private foundations.

Treatment

[edit]
A malnourished Afghan child being treated by a medical team
A Somali boy receiving treatment for malnourishment at a health facility

Improving nutrition

[edit]

Efforts such as infant and young child feeding practices to improve nutrition are some of the common forms of development aid.[6][155] Interventions often promote breastfeeding to reduce rates of malnutrition and death in children.[1] Some of these interventions have been successful.[7] For example, interventions with commodities such as ready to use therapeutic foods, ready to use supplementary foods, micronutrient intervention and vitamin supplementation were identified to significantly improve nutrition, reduce stunting and prevent diseases in communities with severe acute malnutrition.[82] In young children, outcomes improve when children between six months and two years of age receive complementary food (in addition to breast milk).[7] There is also good evidence that supports giving supplemental micronutrients to pregnant women and young children in the developing world.[7]

The United Nations has reported on the importance of nutritional counselling and support, for example in the care of HIV-infected persons, especially in "resource-constrained settings where malnutrition and food insecurity are endemic".[156] UNICEF provides nutritional counselling services for malnourished children in Afghanistan.[157]

Sending food and money is a common form of development aid, aimed at feeding hungry people. Some strategies help people buy food within local markets.[6][158] Simply feeding students at school is insufficient.[6]

Longer-term measures include improving agricultural practices,[159] reducing poverty, and improving sanitation.

Identifying malnourishment

[edit]

Measuring children is crucial to identifying malnourishment. In 2000, the United States Centers for Disease Control and Prevention (CDC) established the International Micronutrient Malnutrition Prevention and Control (IMMPaCt) program. It tested children for malnutrition by conducting a three-dimensional scan, using an iPad or a tablet. Its objective was to help doctors provide more efficient treatments.[160] There may be some chance of error when using this method.[160] The Screening Tool for the Assessment of Malnutrition in Paediatrics (STAMPa) is another method for the identification and evaluation of malnutrition in young children.[161] The assessment tool has fair to medium reliability in the identification of children at risk of malnutrition.[161]

A systematic review of 42 studies found that many approaches to mitigating acute malnutrition are equally effective; thus, intervention decisions can be based on cost-related factors. Overall, evidence for the effectiveness of acute malnutrition interventions is not robust. The limited evidence related to cost indicates that community and outpatient management of children with uncomplicated malnutrition may be the most cost-effective strategy.[162]

Regularly measuring and charting children's growth and including activities to promote health (an intervention called growth monitoring and promotion, also known as GPM) is often considered by policy makers and is recommended by the World Health Organization.[163] This program is often performed at the same time as a child has their regular immunizations.[164] Despite widespread use of this type of program, further studies are needed to understand the impact of these programs on overall child health and how to better address faltering growth in a child and improve practices related to feeding children in lower to middle income countries.[164]

Medical management

[edit]

It is often possible to manage severe malnutrition within a person's home, using ready-to-use therapeutic foods.[7] In people with severe malnutrition complicated by other health problems, treatment in a hospital setting is recommended.[7] In-hospital treatment often involves managing low blood sugar, maintaining adequate body temperature, addressing dehydration, and gradual feeding.[7][165]

Routine antibiotics are usually recommended because malnutrition weakens the immune system, causing a high risk of infection.[165] Additionally, broad spectrum antibiotics are recommended in all severely undernourished children with diarrhea requiring admission to hospital.[166]

A severely malnourished child who appears to have dehydration, but has not had diarrhea, should be treated as if they have an infection.[166]

Among malnourished people who are hospitalized, nutritional support improves protein intake, calorie intake, and weight.[167]

Bangladeshi model

[edit]
Baby with protein malnutrition due to insufficient amount of nutrients

In response to child malnutrition, the Bangladeshi government recommends ten steps for treating severe malnutrition:[168]

  1. Prevent or treat dehydration
  2. Prevent or treat low blood sugar
  3. Prevent or treat low body temperature
  4. Prevent or treat infection;
  5. Correct electrolyte imbalances
  6. Correct micronutrient deficiencies
  7. Start feeding cautiously
  8. Achieve catch-up growth
  9. Provide psychological support
  10. Prepare for discharge and follow-up after recovery

Therapeutic foods

[edit]

Due in part to limited research on supplementary feeding, there is little evidence that this strategy is beneficial.[169] A 2015 systematic review of 32 studies found that there are limited benefits when children under 5 receive supplementary feeding, especially among younger, poorer, and more undernourished children.[170]

However, specially formulated foods do appear to be useful in treating moderate acute malnutrition in the developing world.[171] These foods may have additional benefits in humanitarian emergencies, since they can be stored for years, can be eaten directly from the packet, and do not have to be mixed with clean water or refrigerated.[172] In young children with severe acute malnutrition, it is unclear if ready-to-use therapeutic food differs from a normal diet.[173]

Severely malnourished individuals can experience refeeding syndrome if fed too quickly.[174] Refeeding syndrome can result regardless of whether food is taken orally, enterally or parenterally.[174] It can present several days after eating with potentially fatal heart failure, dysrhythmias, and confusion.[174][175]

Some manufacturers have fortified everyday foods with micronutrients before selling them to consumers. For example, flour has been fortified with iron, zinc, folic acid, and other B vitamins like thiamine, riboflavin, niacin and vitamin B12.[107] Baladi bread (Egyptian flatbread) is made with fortified wheat flour. Other fortified products include fish sauce in Vietnam and iodized salt.[172]

Micronutrient supplementation

[edit]

According to the World Bank, treating malnutrition – mostly by fortifying foods with micronutrients – improves lives more quickly than other forms of aid, and at a lower cost.[176] After reviewing a variety of development proposals, The Copenhagen Consensus, a group of economists who reviewed a variety of development proposals, ranked micronutrient supplementation as its number-one treatment strategy.[177][130]

In malnourished people with diarrhea, zinc supplementation is recommended following an initial four-hour rehydration period. Daily zinc supplementation can help reduce the severity and duration of the diarrhea. Additionally, continuing daily zinc supplementation for ten to fourteen days makes diarrhea less likely to recur in the next two to three months.[178]

Malnourished children also need both potassium and magnesium.[168] Within two to three hours of starting rehydration, children should be encouraged to take food, particularly foods rich in potassium[168][178] like bananas, green coconut water, and unsweetened fresh fruit juice.[178] Along with continued eating, many homemade products can also help restore normal electrolyte levels. For example, early during the course of a child's diarrhea, it can be beneficial to provide cereal water (salted or unsalted) or vegetable broth (salted or unsalted).[178] If available, vitamin A, potassium, magnesium, and zinc supplements should be added, along with other vitamins and minerals.[168]

Giving base (as in Ringer's lactate) to treat acidosis without simultaneously supplementing potassium worsens low blood potassium.[178]

Treating diarrhea

[edit]

Preventing dehydration

[edit]

Food and drink can help prevent dehydration in malnourished people with diarrhea. Eating (or breastfeeding, among infants) should resume as soon as possible.[166] Sugary beverages like soft drinks, fruit juices, and sweetened teas are not recommended as they may worsen diarrhea.[179]

Malnourished people with diarrhea (especially children) should be encouraged to drink fluids; the best choices are fluids with modest amounts of sugar and salt, like vegetable broth or salted rice water. If clean water is available, they should be encouraged to drink that too. Malnourished people should be allowed to drink as much as they want, unless signs of swelling emerge.

Babies can be given small amounts of fluids via an eyedropper or a syringe without the needle. Children under two should receive a teaspoon of fluid every one to two minutes; older children and adults should take frequent sips of fluids directly from a cup.[178] After the first two hours, fluids and foods should be alternated, rehydration should be continued at the same rate or more slowly, depending on how much fluid the child wants and whether they are having ongoing diarrhea.[168]

If vomiting occurs, fluids can be paused for 5–10 minutes and then restarted more slowly. Vomiting rarely prevents rehydration, since fluids are still absorbed and vomiting is usually short-term.[179]

Oral rehydration therapy

[edit]

If prevention has failed and dehydration develops, the preferred treatment is rehydration through oral rehydration therapy (ORT). In severely undernourished children with diarrhea, rehydration should be done slowly, according to the World Health Organization.

Oral rehydration solutions consist of clean water mixed with small amounts of sugars and salts. These solutions help restore normal electrolyte levels, provide a source of carbohydrates, and help with fluid replacement.[180]

Reduced-osmolarity ORS is the current standard of care for oral rehydration therapy, with reasonably wide availability.[181][182] Introduced in 2003 by WHO and UNICEF, reduced-osmolarity solutions contain lower concentrations of sodium and glucose than original ORS preparations. Reduced-osmolarity ORS has the added benefit of reducing stool volume and vomiting while simultaneously preventing dehydration. Packets of reduced-osmolarity ORS include glucose, table salt, potassium chloride, and trisodium citrate. For general use, each packet should be mixed with a liter of water. However, for malnourished children, experts recommend adding a packet of ORS to two liters of water, along with an extra 50 grams of sucrose and some stock potassium solution.[183]

People who have no access to commercially available ORS can make a homemade version using water, sugar, and table salt. Experts agree that homemade ORS preparations should include one liter (34 oz.) of clean water and 6 teaspoons of sugar; however, they disagree about whether they should contain half a teaspoon of table salt or a full teaspoon. Most sources recommend using half a teaspoon of salt per liter of water.[178][184][185][186] However, people with malnutrition have an excess of body sodium.[168] To avoid worsening this symptom, ORS for people with severe undernutrition should contain half the usual amount of sodium and more potassium.

Patients who do not drink may require fluids by nasogastric tube. Intravenous fluids are recommended only in those who have significant dehydration due to their potential complications, including congestive heart failure.[166]

Examples of commercially available oral rehydration salts (Nepal on left, Peru on right)

Low blood sugar

[edit]

Hypoglycemia, whether known or suspected, can be treated with a mixture of sugar and water. If the patient is conscious, the initial dose of sugar and water can be given by mouth.[187] Otherwise, they should receive glucose by intravenous or nasogastric tube. If seizures occur (and continue after glucose is given), rectal diazepam may be helpful. Blood sugar levels should be re-checked on two-hour intervals.[168]

Hypothermia

[edit]

Hypothermia (dangerously low core body temperature) can occur in malnutrition, particularly in children. Mild hypothermia causes confusion, trembling, and clumsiness; more severe cases can be fatal. Keeping malnourished children warm can prevent or treat hypothermia. Covering the child (including their head) in blankets is one method. Another method is to warm the child through direct skin-to-skin contact with their mother or father, then covering both parent and child.

Warming methods are usually most important at night.[168] Prolonged bathing or prolonged medical exams can further lower body temperature and are not recommended for malnourished children at high risk of hypothermia.

Epidemiology

[edit]
Percentage of population suffering from hunger, World Food Programme, 2020:
  < 2.5%
  < 5.0%
  5.0–14.9%
  15.0–24.9%
  25.0–34.9%
  > 35.0%
  No data
Disability-adjusted life year for nutritional deficiencies per 100,000 inhabitants in 2004. Nutritional deficiencies included: protein-energy malnutrition, iodine deficiency, vitamin A deficiency, and iron deficiency anaemia.[188]

The figures provided in this section on epidemiology all refer to undernutrition even if the term malnutrition is used which, by definition, could also apply to too much nutrition.

The Global Hunger Index (GHI) is a multidimensional statistical tool used to describe the state of countries' hunger situation. The GHI measures progress and failures in the global fight against hunger.[189] The GHI is updated once a year. The data from the 2015 report shows that Hunger levels have dropped 27% since 2000. Fifty two countries remain at serious or alarming levels. In addition to the latest statistics on Hunger and Food Security, the GHI also features different special topics each year. The 2015 report include an article on conflict and food security.[190]

People affected

[edit]

The United Nations estimated that there were 821 million undernourished people in the world in 2017. This is using the UN's definition of 'undernourishment', where it refers to insufficient consumption of raw calories, and so does not necessarily include people who lack micro nutrients.[43] The undernourishment occurred despite the world's farmers producing enough food to feed around 12 billion people—almost double the current world population.[191]

Malnutrition, as of 2010, was the cause of 1.4% of all disability adjusted life years.[192]

Number of undernourished globally[193]
Year 2005 2006 2007 2008 2009 2010 2011 2012 2013
Number in millions 793.4 746.5 691.0 663.1 661.8 597.8 578.3 580.0 572.3
Percentage (%) 12.1% 11.2% 10.3% 9.7% 9.6% 8.6% 8.2% 8.1% 7.9%
Year 2014 2015 2016 2017 2018 2019 2020 2021 2022
Number in millions 563.9 588.9 586.4 571.8 586.8 612.8 701.4 738.9 735.1
Percentage (%) 7.7% 7.9% 7.8% 7.5% 7.6% 7.9% 8.9% 9.3% 9.2%
Number of undernourished in the developing world[194][195][196]
Year 1970 1980 1991 1996 2002 2004 2006 2011
Number in millions 875 841 820 790 825 848 927 805
Percentage (%) 37% 28% 20% 18% 17% 16% 17% 14%
Deaths from nutritional deficiencies per million persons in 2012:
  0–4
  5–8
  9–13
  14–23
  24–34
  35–56
  57–91
  92–220
  221–365
  366–1,207

In 2010 protein-energy malnutrition resulted in 600,000 deaths down from 883,000 deaths in 1990.[197] Other nutritional deficiencies, which include iodine deficiency and iron deficiency anemia, result in another 84,000 deaths.[197] In 2010 malnutrition caused about 1.5 million deaths in women and children.[198]

According to the World Health Organization, malnutrition is the biggest contributor to child mortality, present in half of all cases.[199] Six million children die of hunger every year.[200] Underweight births and intrauterine growth restrictions cause 2.2 million child deaths a year. Poor or non-existent breastfeeding causes another 1.4 million. Other deficiencies, such as lack of vitamin A or zinc, for example, account for 1 million. Malnutrition in the first two years is irreversible. Malnourished children grow up with worse health and lower education achievement. Their own children tend to be smaller. Malnutrition was previously[when?] seen as something that exacerbates the problems of diseases such as measles, pneumonia and diarrhea, but malnutrition actually causes diseases, and can be fatal in its own right.[199]

History

[edit]

Hunger has been a perennial human problem. However, until the early 20th century, there was relatively little awareness of the qualitative aspects of malnutrition.

Throughout history, various peoples have known the importance of eating certain foods to prevent symptoms now associated with malnutrition. Yet such knowledge appears to have been repeatedly lost and then re-discovered. For example, the ancient Egyptians reportedly knew the symptoms of scurvy. Much later, in the 14th century, Crusaders sometimes used anti-scurvy measures – for example, ensuring that citrus fruits were planted on Mediterranean islands, for use on sea journeys. However, for several centuries, Europeans appear to have forgotten the importance of these measures. They rediscovered this knowledge in the 18th century, and by the early 19th century, the Royal Navy was issuing frequent rations of lemon juice to every crewman on their ships. This massively reduced scurvy deaths among British sailors, which in turn gave the British a significant advantage in the Napoleonic Wars. Later on in the 19th century, the Royal Navy replaced lemons with limes (unaware at the time that lemons are far more effective at preventing scurvy).[201][202]

According to historian Michael Worboys, malnutrition was essentially discovered, and the science of nutrition established, between World War I and World War II. Advances built on prior works like Casimir Funk's 1912 formulisation of the concept of vitamins. Scientific study of malnutrition increased in the 1920s and 1930s, and grew even more common after World War II.

Non-governmental organizations and United Nations agencies began to devote considerable energy to alleviating malnutrition around the world. The exact methods and priorities for doing this tended to fluctuate over the years, with varying levels of focus on different types of malnutrition like Kwashiorkor or Marasmus; varying levels of concern on protein deficiency compared to vitamins, minerals and lack of raw calories; and varying priorities given to the problem of malnutrition in general compared to other health and development concerns. The green Revolution of the 1950s and 1960s saw considerable improvement in capability to prevent malnutrition.[202][201][203]

One of the first official global documents addressing Food security and global malnutrition was the 1948 Universal Declaration of Human Rights(UDHR). Within this document it stated that access to food was part of an adequate right to a standard of living.[204] The Right to food was asserted in the International Covenant on Economic, Social and Cultural Rights, a treaty adopted by the United Nations General Assembly on December 16, 1966. The Right to food is a human right for people to feed themselves in dignity, be free from hunger, food insecurity, and malnutrition.[205] As of 2018, the treaty has been signed by 166 countries, by signing states agreed to take steps to the maximum of their available resources to achieve the right to adequate food.

However, after the 1966 International Covenant the global concern for the access to sufficient food only became more present, leading to the first ever World Food Conference that was held in 1974 in Rome, Italy. The Universal Declaration on the Eradication of Hunger and Malnutrition was a UN resolution adopted November 16, 1974 by all 135 countries that attended the 1974 World Food Conference.[206] This non-legally binding document set forth certain aspirations for countries to follow to sufficiently take action on the global food problem. Ultimately this document outline and provided guidance as to how the international community as one could work towards fighting and solving the growing global issue of malnutrition and hunger.

Adoption of the right to food was included in the Additional Protocol to the American Convention on Human Rights in the area of Economic, Social, and Cultural Rights, this 1978 document was adopted by many countries in the Americas, the purpose of the document is, "to consolidate in this hemisphere, within the framework of democratic institutions, a system of personal liberty and social justice based on respect for the essential rights of man."[207]

A later document in the timeline of global initiatives for malnutrition was the 1996 Rome Declaration on World Food Security, organized by the Food and Agriculture Organization. This document reaffirmed the right to have access to safe and nutritious food by everyone, also considering that everyone gets sufficient food, and set the goals for all nations to improve their commitment to food security by halving their number of undernourished people by 2015.[208] In 2004 the Food and Agriculture Organization adopted the Right to Food Guidelines, which offered states a framework of how to increase the right to food on a national basis.

Special populations

[edit]

Undernutrition is an important determinant of maternal and child health, accounting for more than a third of child deaths and more than 10 percent of the total global disease burden according to 2008 studies.[209]

Children

[edit]
Malnourished children in Niger, during the 2005 famine

Undernutrition adversely affects the cognitive development of children, contributing to poor earning capacity and poverty in adulthood.[210] The development of childhood undernutrition coincides with the introduction of complementary weaning foods which are usually nutrient deficient.[211] The World Health Organization estimated in 2008 that malnutrition accounted for 54 percent of child mortality worldwide,[60] about 1 million children.[212] There is a strong association between undernutrition and child mortality.[213]

Another estimate in 2008 also by WHO stated that childhood underweight was the cause for about 35% of all deaths of children under the age of five years worldwide.[214] Over 90% of the stunted children below five years of age live in sub-Saharan Africa and South Central Asia.[82] Although access to adequate food and improving nutritional intake is an obvious solution to tackling undernutrition in children, the progress in reducing children undernutrition has been disappointing.[215]

Women

[edit]
Migrant Mother by Dorothea Lange (1936)
Starved girl

In 2022, more than 1 billion adolescent girls and women suffered from undernutrition, according to UNICEF's 2023 report "Undernourished and Overlooked: A Global Nutrition Crisis in Adolescent Girls and Women".[216] The gender gap in food insecurity more than doubled between 2019 (49 million) and 2021 (126 million). The report shows that globally, 30% of women aged 15–49 years are living with anaemia while 10 per cent of women aged 20–49 years suffer from underweight. South Asia, West and Central Africa and Eastern and Southern Africa are home to 60% of women with anaemia and 65% of women being underweight. In contrast, overweight is affecting more than 35% of women aged 20–49 years, of which 13% are living with obesity.[216]

The Middle East and North Africa has the highest prevalence of overweight with 61% affected. North America closely follows at 60%.[216] Fewer than 1 in 3 adolescent girls and women have diets meeting the minimum dietary diversity in the Sudan (10%), Burundi (12%), Burkina Faso (17%) and Afghanistan (26%).[216] In Niger, the percentage of women accessing a minimally diverse diet fell from 53% to 37% between 2020 and 2022.[216]

Researchers from the Centre for World Food Studies in 2003 found that the gap between levels of undernutrition in men and women is generally small, but that the gap varies from region to region and from country to country.[217] These small-scale studies showed that female undernutrition prevalence rates exceeded male undernutrition prevalence rates in South/Southeast Asia and Latin America and were lower in Sub-Saharan Africa.[217] Datasets for Ethiopia and Zimbabwe reported undernutrition rates between 1.5 and 2 times higher in men than in women; however, in India and Pakistan, datasets rates of undernutrition were 1.5–2 times higher in women than in men. Intra-country variation also occurs, with frequent high gaps between regional undernutrition rates.[217] Gender inequality in nutrition in some countries such as India is present in all stages of life.[218]

Studies on nutrition concerning gender bias within households look at patterns of food allocation, and one study from 2003 suggested that women often receive a lower share of food requirements than men.[217] Gender discrimination, gender roles, and social norms affecting women can lead to early marriage and childbearing, close birth spacing, and undernutrition, all of which contribute to malnourished mothers.[84]

Within the household, there may be differences in levels of malnutrition between men and women, and these differences have been shown to vary significantly from one region to another, with problem areas showing relative deprivation of women.[217] Samples of 1000 women in India in 2008 demonstrated that malnutrition in women is associated with poverty, lack of development and awareness, and illiteracy.[218] The same study showed that gender discrimination in households can prevent a woman's access to sufficient food and healthcare.[218] How socialization affects the health of women in Bangladesh, Najma Rivzi explains in an article about a research program on this topic.[219] In some cases, such as in parts of Kenya in 2006, rates of malnutrition in pregnant women were even higher than rates in children.[220]

Women in some societies are traditionally given less food than men since men are perceived to have heavier workloads.[221] Household chores and agricultural tasks can in fact be very arduous and require additional energy and nutrients; however, physical activity, which largely determines energy requirements, is difficult to estimate.[217]

Physiology

[edit]

Women have unique nutritional requirements, and in some cases need more nutrients than men; for example, women need twice as much calcium as men.[221]

Pregnancy and breastfeeding

[edit]

During pregnancy and breastfeeding, women must ingest enough nutrients for themselves and their child, so they need significantly more protein and calories during these periods, as well as more vitamins and minerals (especially iron, iodine, calcium, folic acid, and vitamins A, C, and K).[221] In 2001 the FAO of the UN reported that iron deficiency affected 43 percent of women in developing countries and increased the risk of death during childbirth.[221] A 2008 review of interventions estimated that universal supplementation with calcium, iron, and folic acid during pregnancy could prevent 105,000 maternal deaths (23.6 percent of all maternal deaths).[222] Malnutrition has been found to affect three-quarters of UK women aged 16–49 indicated by them having less folic acid than the WHO recommended levels.[223]

Frequent pregnancies with short intervals between them and long periods of breastfeeding add an additional nutritional burden.[217]

Educating children

[edit]

"Action for Healthy Kids" has created several methods to teach children about nutrition. They introduce 2 different topics, self-awareness which teaches children about taking care of their own health and social awareness, which is how culinary arts vary from culture to culture. As well as its importance when it comes to nutrition. They include eBooks, tips, cooking clubs. including facts about vegetables and fruits.[224]

Team Nutrition has created "MyPlate eBooks" this includes 8 different eBooks to download for free. These eBooks contain drawings to color, audio narration, and a large number of characters to make nutrition lessons entertaining for children.[225]

According to the FAO, women are often responsible for preparing food and have the chance to educate their children about beneficial food and health habits, giving mothers another chance to improve the nutrition of their children.[221]

Elderly

[edit]
Essential nutrients are one of the main requirements of elderly care.

Malnutrition and being underweight are more common in the elderly than in adults of other ages.[226] If elderly people are healthy and active, the aging process alone does not usually cause malnutrition.[227] However, changes in body composition, organ functions, adequate energy intake and ability to eat or access food are associated with aging, and may contribute to malnutrition.[228] Sadness or depression can play a role, causing changes in appetite, digestion, energy level, weight, and well-being.[227] A study on the relationship between malnutrition and other conditions in the elderly found that malnutrition in the elderly can result from gastrointestinal and endocrine system disorders, loss of taste and smell, decreased appetite and inadequate dietary intake.[228] Poor dental health, ill-fitting dentures, or chewing and swallowing problems can make eating difficult.[227] As a result of these factors, malnutrition is seen to develop more easily in the elderly.[229]

Rates of malnutrition tend to increase with age with less than 10 percent of the "young" elderly (up to age 75) malnourished, while 30 to 65 percent of the elderly in home care, long-term care facilities, or acute hospitals are malnourished.[230] Many elderly people require assistance in eating, which may contribute to malnutrition.[229] However, the mortality rate due to undernourishment may be reduced.[231] Because of this, one of the main requirements of elderly care is to provide an adequate diet and all essential nutrients.[232] Providing the different nutrients such as protein and energy keeps even small but consistent weight gain.[231] Hospital admissions for malnutrition in the United Kingdom have been related to insufficient social care, where vulnerable people at home or in care homes are not helped to eat.[233]

In Australia malnutrition or risk of malnutrition occurs in 80 percent of elderly people presented to hospitals for admission.[234] Malnutrition and weight loss can contribute to sarcopenia with loss of lean body mass and muscle function.[226] Abdominal obesity or weight loss coupled with sarcopenia lead to immobility, skeletal disorders, insulin resistance, hypertension, atherosclerosis, and metabolic disorders.[228] A paper from the Journal of the American Dietetic Association noted that routine nutrition screenings represent one way to detect and therefore decrease the prevalence of malnutrition in the elderly.[227]

See also

[edit]

Sources

[edit]

 This article incorporates text from a free content work. Licensed under CC BY-SA 4.0 (license statement/permission). Text taken from The State of Food Security and Nutrition in the World 2024​, Food and Agriculture Organization.

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia
from Grokipedia

Malnutrition refers to deficiencies, excesses, or imbalances in a person's of energy and/or nutrients, which adversely affect the body's tissues, form, and function. It encompasses undernutrition (including , stunting, and ), micronutrient-related malnutrition (such as deficiencies in iron, iodine, , and ), and leading to , , and associated noncommunicable diseases like and cardiovascular conditions.
Globally, malnutrition imposes a profound health burden, with approximately 150 million children under five years stunted in 2024 due to chronic undernutrition, impairing physical and , while 43 million suffered from acute wasting, heightening mortality risk from infections. Around 673 million people experienced in 2024, predominantly in and parts of , driven by , insecurity, conflict, and variability that disrupt agricultural production and access to diverse foods. deficiencies affect over two billion individuals, causing in nearly 40% of pregnant women and weakening immune responses, while contributes to more than one billion adults being obese, fueling a rise in diet-related chronic diseases even in low-income settings where undernutrition persists concurrently. Primary causes include inadequate dietary diversity, from diseases like or parasites, increased metabolic demands during illness, and socioeconomic factors limiting access to nutrient-dense foods, with empirical evidence linking these to reduced intake, heightened losses, or poor absorption rather than isolated genetic or environmental anomalies. Consequences extend to elevated —accounting for nearly half of deaths under five—and long-term economic losses, underscoring malnutrition's role as a causal driver of intergenerational cycles of impaired .

Definition and Classification

Core Definitions and Diagnostic Criteria

Malnutrition encompasses deficiencies, excesses, or imbalances in an individual's intake of energy and/or essential nutrients, adversely affecting bodily functions, growth, and health. This broad definition, as articulated by the (WHO), includes undernutrition (characterized by insufficient caloric or protein intake leading to conditions such as , stunting, and ), (excessive energy intake resulting in , , and associated comorbidities), and micronutrient-related malnutrition (insufficient or excessive vitamins, minerals, or other micronutrients causing specific deficiencies or toxicities). While no single universal definition exists due to contextual variations in and measurement, clinical and frameworks prioritize empirical indicators like , biochemical assessments, and clinical signs to establish . In children aged 6–59 months, WHO diagnostic criteria for undernutrition rely on standardized anthropometric z-scores relative to WHO Child Growth Standards: wasting is defined as weight-for-length/height below -2 standard deviations (SD), with severe acute malnutrition indicated by z-scores below -3 SD, mid-upper arm circumference (MUAC) below 115 mm, or the presence of bilateral pitting edema (as in kwashiorkor). Stunting reflects chronic undernutrition via height-for-age below -2 SD, while underweight uses weight-for-age below -2 SD; these metrics enable early identification in resource-limited settings, where MUAC is particularly valued for its simplicity and correlation with mortality risk exceeding 9% in severe cases without intervention. Overnutrition in children is diagnosed via weight-for-length/height above +2 SD or +3 SD for overweight and obesity, respectively, often assessed alongside micronutrient status to detect imbalances. For adults, the Global Leadership Initiative on Malnutrition (GLIM), a 2018 consensus from major societies, requires fulfillment of at least one phenotypic criterion (e.g., unintentional >5% within 6 months or >10% beyond 6 months; [BMI] <20 kg/m² for those under 70 years or <22 kg/m² for those 70+; or reduced muscle mass via clinical or instrumental measures) combined with at least one etiologic criterion (reduced food intake/assimilation or presence of inflammation/disease burden) for diagnosis. Severity is then graded: Stage 1 (moderate) for values meeting minimal cutoffs, and Stage 2 (severe) for more pronounced deficits, such as >10% or BMI <18.5 kg/m². Complementary frameworks, like the European Society for Clinical Nutrition and Metabolism (ESPEN) criteria, diagnose malnutrition via BMI <18.5 kg/m² or combined unintentional with reduced BMI (<20 kg/m² if <70 years, <22 kg/m² if ≥70) or fat-free mass index <15 kg/m² (men) or <12 kg/m² (women). Overnutrition diagnostics emphasize BMI ≥30 kg/m² for obesity alongside evidence of nutrient excesses, such as elevated triglycerides or insulin resistance, though these are often contextualized within broader metabolic syndrome assessments. Micronutrient malnutrition diagnosis integrates clinical symptoms (e.g., night blindness for vitamin A deficiency, goiter for iodine deficiency), biochemical markers (e.g., serum retinol <0.70 μmol/L for vitamin A deficiency, hemoglobin <110 g/L in children for anemia, serum 25-hydroxyvitamin D for vitamin D stores, vitamin B12, folate, and ferritin for iron stores), and dietary history, with WHO thresholds guiding population-level screening. Pediatric criteria adapt adult frameworks using growth percentiles or z-scores, with severity stratified by degree of deviation (mild: -1 to -2 SD; moderate: -2 to -3 SD; severe: below -3 SD) across weight, height, and head circumference. These criteria underscore malnutrition's multifactorial nature, necessitating integrated evaluation to distinguish acute from chronic forms and guide interventions.

Classification Systems and Metrics

Malnutrition is classified into three primary categories: undernutrition, micronutrient-related malnutrition, and overweight or obesity, as delineated by the World Health Organization (WHO). These classifications rely on anthropometric, biochemical, and clinical metrics to assess nutritional status, with anthropometric indicators forming the core for undernutrition and overnutrition due to their non-invasive, standardized nature. For children under five years, the WHO Child Growth Standards provide reference medians derived from multicountry growth data of healthy breastfed infants, using Z-scores (standard deviations from the median) to quantify deviations. In children, undernutrition subtypes are measured via height-for-age Z-score (HAZ) for stunting (chronic malnutrition), weight-for-height Z-score (WHZ) for wasting (acute malnutrition), and weight-for-age Z-score (WAZ) for underweight (composite indicator). Stunting is defined as HAZ below -2 SD, indicating impaired linear growth often from prolonged nutrient deficits or infections; severe stunting uses -3 SD. Wasting corresponds to WHZ below -2 SD, with severe wasting below -3 SD or presence of nutritional edema (kwashiorkor); mid-upper arm circumference (MUAC) below 115 mm serves as a complementary field metric for severe acute malnutrition in children 6-59 months. Underweight is WAZ below -2 SD, capturing both stunted and wasted children but unable to distinguish them. Overweight in children is WHZ above +2 SD or above +3 SD for obesity. For adults, body mass index (BMI), calculated as weight in kilograms divided by height in meters squared, is the primary metric, with undernutrition indicated by BMI below 18.5 kg/m² (moderate) or below 16 kg/m² (severe). MUAC offers a practical alternative in resource-limited settings, correlating strongly with BMI; proposed cutoffs include below 23 cm for women and below 24.5 cm for men to detect undernutrition, though these lack universal WHO endorsement and vary by population. Overnutrition uses BMI above 25 kg/m² for overweight and above 30 kg/m² for obesity. The Composite Index of Anthropometric Failure (CIAF) integrates multiple child indicators to estimate total undernutrition prevalence, revealing overlaps missed by single metrics like stunting alone. Micronutrient deficiencies are classified by specific nutrient shortfalls, assessed via biochemical markers such as hemoglobin for iron deficiency anemia (<11 g/dL in children 6-59 months per WHO), serum retinol for vitamin A (<0.70 µmol/L indicating deficiency), or urinary iodine for iodine status. Clinical signs (e.g., night blindness for vitamin A) and dietary intake metrics supplement these, but anthropometry does not directly measure micronutrient status. Joint UNICEF-WHO-World Bank estimates standardize global tracking of these indicators, using modeled data from surveys to monitor progress against .
IndicatorMetricThreshold for Malnutrition (Children <5 years)Source
StuntingHAZ< -2 SD (moderate), < -3 SD (severe)WHO Child Growth Standards
WastingWHZ or MUAC< -2 SD (moderate), < -3 SD or MUAC <115 mm (severe with edema)WHO/UNICEF
UnderweightWAZ< -2 SDWHO Child Growth Standards
OverweightWHZ> +2 SDWHO Child Growth Standards

Forms of Malnutrition

Undernutrition Subtypes

Undernutrition encompasses several interrelated subtypes, primarily distinguished by anthropometric indicators and clinical presentations, as defined by the (WHO). These include wasting, stunting, and underweight, which reflect acute and chronic deficits in energy and nutrient intake, often exacerbated by infection or poor absorption. Wasting represents acute undernutrition, characterized by low weight-for-height (below -2 standard deviations [SD] of the WHO median growth standards for age and sex), signaling recent rapid due to insufficient caloric intake, , or both; severe wasting occurs below -3 SD and carries a high mortality risk if untreated. Stunting denotes chronic undernutrition, defined as low height-for-age (below -2 SD), resulting from prolonged or recurrent nutrient deficiencies that impair linear growth, particularly or during ; severe stunting is below -3 SD and is associated with irreversible cognitive and physical developmental deficits. Underweight, a composite indicator of low weight-for-age (below -2 SD), can arise from either acute wasting, chronic stunting, or a combination, serving as a broad screening tool but less specific for . Severe forms of acute undernutrition, often falling under , manifest as distinct syndromes: and . Marasmus results from prolonged total caloric deprivation, leading to extreme , muscle , and loss of subcutaneous fat, with preserved alertness despite weakness; it primarily affects infants and young children deprived of both macronutrients, causing metabolic adaptations like reduced basal energy expenditure to conserve resources. Kwashiorkor, conversely, stems from predominant protein deficiency amid relatively adequate non-protein calories, characterized by bilateral pitting (often starting in the feet and legs), dermatosis, , and a distended due to and fluid retention; and are common, distinguishing it from marasmus, though mixed marasmic-kwashiorkor cases frequently occur with overlapping features like atop . These syndromes elevate risks for infections, electrolyte imbalances, and mortality, with kwashiorkor historically linked to practices in resource-limited settings where carbohydrate-heavy diets displace protein sources. In clinical assessment, moderate acute malnutrition (MAM) involves weight-for-height between -3 and -2 SD without complications, amenable to outpatient management, while severe acute malnutrition (SAM) requires inpatient stabilization due to risks like , , and ; WHO guidelines emphasize mid-upper arm circumference (MUAC <115 mm for SAM in children 6-59 months) as a simple field measure complementary to weight-for-height z-scores (WHZ). Chronic undernutrition via stunting correlates with fetal and early-life insults, with global data indicating 149 million children stunted in 2020, predominantly in South Asia and sub-Saharan Africa, where it perpetuates cycles of impaired immunity and productivity. These subtypes are not mutually exclusive, as undernutrition often progresses from acute episodes to chronic states without intervention, underscoring the need for integrated screening using multiple indicators. Overnutrition constitutes a form of malnutrition characterized by excessive intake of calories or specific nutrients, leading to the pathological accumulation of body fat that impairs health and physiological function. Unlike undernutrition, which stems from insufficient energy or nutrient availability, overnutrition arises from chronic energy surplus where caloric consumption exceeds expenditure, resulting in adipose tissue expansion beyond adaptive limits. This imbalance disrupts metabolic homeostasis, promoting insulin resistance, inflammation, and oxidative stress as core causal mechanisms. The hallmark condition of overnutrition is obesity, clinically defined by a body mass index (BMI) of ≥30 kg/m², with overweight (BMI 25–29.9 kg/m²) representing a precursor state. Globally, obesity affected over 1 billion individuals in 2022, with prevalence more than doubling since 1990, driven by shifts toward energy-dense diets high in refined carbohydrates and fats alongside sedentary behaviors. Projections indicate a 30.7% rise in age-standardized overweight and obesity prevalence worldwide by 2055, disproportionately burdening low- and middle-income countries where 79% of such cases are expected by 2035.00355-1/fulltext) Health consequences of overnutrition extend beyond obesity to include type 2 diabetes, hypertension, cardiovascular disease, non-alcoholic fatty liver disease, and certain cancers, mediated by lipotoxicity and ectopic fat deposition in organs like the liver and pancreas. Excess nutrient intake, particularly of ultra-processed foods rich in added sugars and trans fats, exacerbates these risks by altering gut microbiota, promoting chronic low-grade inflammation, and impairing efferocytosis—the clearance of apoptotic cells—which perpetuates vascular damage. Overnutrition also correlates with cognitive decline, including increased dementia risk, independent of obesity per se, via mechanisms like hypothalamic insulin resistance and blood-brain barrier disruption. Related excesses encompass macronutrient-specific imbalances, such as hypercaloric diets disproportionately high in carbohydrates or lipids, which fuel metabolic syndrome even in non-obese individuals. For instance, chronic overconsumption of fructose from high-fructose corn syrup contributes to hepatic steatosis and dyslipidemia by bypassing regulatory appetite controls in the liver. These patterns often coexist with micronutrient deficiencies—the "double burden" of malnutrition—where caloric excess masks inadequate intake of vitamins and minerals, compounding risks in transitioning economies. Causally, overnutrition's etiology traces to behavioral factors like portion distortion and reduced physical activity, amplified by environmental cues from food marketing, rather than isolated genetic predispositions.

Micronutrient Deficiencies

Micronutrient deficiencies, often termed "hidden hunger," arise from insufficient intake or absorption of essential vitamins and minerals required in trace amounts for physiological functions, despite adequate caloric consumption. These deficiencies affect over 2 billion individuals globally, primarily in low- and middle-income countries, where diets reliant on staple crops like rice or maize lack diversity and bioavailable nutrients. Iron, vitamin A, iodine, and zinc represent the most prevalent, contributing to anemia, impaired immunity, developmental delays, and increased mortality, particularly among children and pregnant women. Iron deficiency, the most common micronutrient shortfall, manifests as anemia, reducing oxygen transport and causing fatigue, cognitive impairment, and reduced work productivity; it affects approximately 40% of children aged 6-59 months, 37% of pregnant women, and 30% of women 15-49 years worldwide. This condition stems from dietary inadequacy, chronic blood loss, or parasitic infections like hookworm, exacerbating maternal hemorrhage risks and perinatal outcomes. Vitamin A deficiency compromises vision, epithelial integrity, and immune response, leading to xerophthalmia, blindness in up to 250,000-500,000 children annually, and heightened infection susceptibility; it prevails in South Asia and sub-Saharan Africa due to low animal product and fortified food consumption.00367-9/fulltext) Iodine deficiency disorders, including goiter and cretinism, impair thyroid function and neurodevelopment, with severe cases causing irreversible IQ reductions of 10-15 points; globally, 1.88 billion people remain at risk, though prevalence has declined via iodized salt programs. Zinc deficiency hinders growth, wound healing, and immunity, associating with diarrhea, pneumonia, and stunting in 17.3% of the global population, particularly where phytate-rich cereals inhibit absorption.00367-9/fulltext) Among preschool-aged children, 56% exhibit deficiency in at least one of iron, zinc, or vitamin A, underscoring compounded risks in monotonous diets.00367-9/fulltext) Consequences extend to adults, where deficiencies link to chronic diseases, though supplementation trials reveal variable efficacy dependent on baseline status and bioavailability.00276-6/fulltext)

Epidemiology and Prevalence

Global and Regional Burden

In 2023, approximately 733 million people, or one in eleven globally, faced hunger, with the prevalence of undernourishment estimated at 9.1 percent of the world population. This figure reflects a stagnation in progress toward reducing undernutrition, exacerbated by conflicts, economic shocks, and climate events. Among children under five years old, 148.1 million were stunted in 2022, indicating chronic undernutrition, while 45 million suffered from wasting, a marker of acute malnutrition. Overnutrition contributes significantly to the dual burden, with over 1 billion adults and adolescents living with obesity in 2022, equivalent to one in eight people worldwide, a rate that has more than doubled since 1990. Micronutrient deficiencies affect billions, with over 5 billion individuals lacking adequate iodine, vitamin E, or calcium intake, and more than 4 billion deficient in other key nutrients like iron and folate, leading to hidden hunger that impairs health and productivity.00276-6/fulltext) Regionally, sub-Saharan Africa bears the heaviest burden of undernutrition, where one in five people—about 20 percent—was undernourished in 2023, compared to lower rates in Asia (around 8 percent) and Latin America (under 5 percent). In Africa, prevalence varies, with Western Africa at 15 percent and Southern Africa at 11 percent in 2022, while Northern Africa remains lowest at 7.5 percent. Southern Asia and parts of Eastern and Western Africa also show high concentrations of populations unable to afford healthy diets, accounting for the majority of those facing severe food insecurity. Conversely, obesity prevalence is highest in high-income regions like North America and Europe, but is rising rapidly in low- and middle-income countries, particularly in the Middle East and North Africa, where rates exceed 30 percent in some nations. The global burden manifests in substantial mortality and morbidity, with nutritional deficiencies contributing to an estimated 3.1 million child deaths annually, though undernutrition's role has declined from 45 percent of under-five deaths in earlier decades due to interventions like vaccination and sanitation improvements. Disability-adjusted life years (DALYs) lost to nutritional deficiencies decreased by 54.9 percent globally from 1990 to 2021, yet persist disproportionately in low-income regions. Projections indicate Africa will see a significant rise in undernourished individuals, from 282 million in 2022 to higher numbers by 2030, underscoring the need for targeted agricultural and economic policies amid population growth and fragility.

Demographic Disparities

Children under five years of age bear the heaviest burden of undernutrition globally, with 23.2% affected by stunting in 2024, reflecting chronic deficits in essential nutrients during critical growth periods. Wasting, an acute form, impacted 12.2 million children under five in severe cases during the same period, predominantly in low-income regions where food insecurity exacerbates vulnerability. In contrast, elderly populations in certain contexts face rising undernutrition risks due to factors like reduced appetite and comorbidities, though data indicate lower overall prevalence compared to children, with global estimates showing increased disability-adjusted life years from malnutrition in older age groups since 1990. Gender disparities manifest variably; among children, stunting prevalence is marginally higher in males than females in many regions, as evidenced by 2024 data showing boys falling below height-for-age thresholds more frequently due to biological growth differences and infection susceptibility. For women of reproductive age, undernutrition and anemia rates remain elevated in low- and middle-income countries (LMICs), contributing to the double burden where undernutrition coexists with rising overweight prevalence, particularly among females in urbanizing areas. Overnutrition, including obesity, shows inverse patterns in high-income settings, with non-Hispanic Black and Hispanic adults exhibiting higher rates—47.8% and 42%, respectively—compared to 33.4% for non-Hispanic Whites in 2011–2012 U.S. data, a disparity persisting across socioeconomic gradients. Geographically, sub-Saharan Africa and South Asia account for the majority of undernourished individuals, with Africa hosting one in five of the global 733 million hungry people in 2023, driven by conflict, economic shocks, and agricultural limitations in low-income nations. Socioeconomic status amplifies these divides, as lower-income households in LMICs experience higher childhood stunting and wasting, while in higher-income countries, obesity correlates with lower education and income levels among certain ethnic groups, underscoring causal links to access barriers rather than isolated behavioral factors. Ethnic disparities in overnutrition further highlight structural influences, with Black women in the U.S. facing steeper obesity gradients tied to historical and environmental determinants beyond caloric intake alone. Global prevalence of undernourishment declined steadily from about 14.2% in 2000–2002 to a low of 7.5% in 2019, affecting roughly 600 million people, before rising to 9.1% or 733 million in 2023 due to factors including conflicts, economic shocks, and climate events. In 2024, the prevalence edged down slightly to 8.2%, impacting approximately 673 million people, though absolute numbers remain elevated compared to pre-2015 levels. Regional disparities persist, with Africa seeing undernourishment rise to nearly 20% of the population in recent years, while Asia and Latin America experienced more modest increases or stabilizations. Child undernutrition indicators show partial progress amid stagnation. Stunting affected 150.2 million children under five in 2024, down from higher rates in the early 2000s, reflecting a global prevalence drop from around 32% in 2000 to 23% currently, though only 28% of countries are on track to halve stunting by 2030 per WHO targets. Wasting impacted 42.8 million children under five in 2024, with severe cases at 12.2 million, showing limited decline since 2010 despite interventions. Overnutrition trends contrast sharply, with adult obesity more than doubling worldwide since 1990 to affect 1 in 8 people (over 1 billion) by 2022, driven by dietary shifts and urbanization in low- and middle-income countries. Projections indicate acceleration, with overweight and obesity expected to reach 51% of the global adult population by 2035 and nearly two-thirds by 2050 under current trajectories, imposing rising health burdens. Overall projections for malnutrition eradication falter against Sustainable Development Goal targets, with undernourishment unlikely to fall below 600 million by 2030 absent major interventions, as highlighted by the 2024 Global Hunger Index score of 18.3 (moderate severity). Concurrently, the dual burden of under- and overnutrition is projected to intensify in transitioning economies, complicating policy responses.

Etiology and Risk Factors

Disease-related malnutrition primarily stems from physiological disruptions that hinder nutrient intake, absorption, digestion, or utilization, or that elevate metabolic requirements beyond normal compensatory mechanisms. These include malabsorption syndromes, where gastrointestinal pathologies impair the uptake of macronutrients and micronutrients; hypermetabolic states induced by infections, malignancies, or trauma; and chronic conditions that exacerbate nutrient losses or suppress appetite through inflammation or organ dysfunction. Such mechanisms often interplay with reduced oral intake due to disease-induced anorexia or dysphagia, amplifying undernutrition risk. Malabsorption syndromes, encompassing disorders like celiac disease, Crohn's disease, and cystic fibrosis, directly compromise intestinal villi integrity or enzyme production, leading to deficiencies in fats, proteins, carbohydrates, and fat-soluble vitamins (A, D, E, K). For instance, exocrine pancreatic insufficiency results in inadequate lipase and protease secretion, causing steatorrhea and progressive malnutrition if untreated. Chronic inflammatory conditions such as inflammatory bowel disease further erode absorptive surfaces via mucosal damage, with studies indicating up to 65-75% of Crohn's patients experiencing weight loss and nutrient deficits at diagnosis. Parasitic infections, including giardiasis or helminthiasis, similarly disrupt enterocyte function, precipitating acute or chronic diarrhea and electrolyte imbalances that hinder nutrient retention. Elevated metabolic demands arise in hypercatabolic states, where conditions like sepsis, burns, or advanced cancer accelerate protein breakdown and energy expenditure by 20-50% above basal rates, outpacing dietary replenishment. Malignancies, particularly gastrointestinal or pancreatic cancers, not only impose oncologic cachexia—characterized by cytokine-driven muscle wasting—but also mechanical obstructions reducing intake. HIV/AIDS exemplifies this through opportunistic infections and chronic inflammation, with untreated patients showing 10-15% higher malnutrition prevalence due to malabsorption and increased caloric needs. Endocrine disorders, such as untreated hyperthyroidism, amplify basal metabolic rate by up to 60%, depleting energy stores despite adequate consumption. Chronic non-communicable diseases heighten vulnerability through compounded physiological insults; for example, chronic kidney disease impairs protein metabolism and acid-base balance, fostering uremic anorexia and anemia-linked deficiencies, while chronic obstructive pulmonary disease elevates respiratory muscle demands, contributing to 20-40% malnutrition rates in advanced stages. In the elderly, age-related physiological declines—such as diminished gastric acid secretion reducing vitamin B12 absorption or sarcopenia curtailing appetite—interact with comorbidities like dementia or heart failure, where up to 50% of institutionalized patients exhibit malnutrition tied to these factors. Genetic conditions like cystic fibrosis exemplify inherent absorptive defects, with pancreatic involvement causing 85-90% of cases to require enzyme replacement to avert severe undernutrition. These disease-driven pathways underscore malnutrition's role as both consequence and amplifier of morbidity, necessitating targeted diagnostic screening in at-risk populations.

Behavioral and Dietary Contributors

Inadequate dietary diversity and reliance on monotonous, staple-based diets, such as those dominated by cereals with low consumption of proteins, fruits, and vegetables, contribute to undernutrition by limiting essential nutrient intake. Poor complementary feeding practices in infants and young children, including infrequent meals, insufficient quantity, and delayed introduction of diverse foods, account for a substantial portion of stunting and wasting, with suboptimal practices linked to 40% of under-two child deaths globally in regions with high malnutrition prevalence. Irregular eating patterns, such as meal skipping or habitual underconsumption driven by convenience or family preferences, further perpetuate energy deficits, particularly in food-insecure households where caregivers prioritize cost over nutritional balance. For overnutrition, excessive intake of energy-dense, nutrient-poor foods—including frequent fast food consumption, large portion sizes, and high-sugar beverages—creates caloric surpluses that promote obesity and related excesses. Sugary soft drink consumption alone contributes a population-attributable risk of 16.4% to obesity in systematic analyses of modifiable behaviors. Rapid eating speed and habitual snacking, often paired with eating while distracted (e.g., watching television), exacerbate overconsumption by impairing satiety signals and extending daily energy intake. Sedentary behaviors, such as prolonged screen time and minimal physical activity, compound dietary excesses by reducing energy expenditure, with higher sedentary risk associated with a 1.46-fold increase in overweight/obesity odds among youth. Insufficient sleep, another modifiable behavior, heightens obesity risk by 15% through disrupted appetite regulation and metabolic function. These patterns often cluster with poor dietary choices, amplifying malnutrition's dual burden in transitioning economies where traditional activity levels decline without corresponding reductions in caloric intake. Micronutrient deficiencies arise from dietary behaviors favoring processed or single-food-group reliance, such as low fruit and vegetable intake, which affects billions globally and underlies "hidden hunger" in apparently sufficient-calorie diets. Avoidance of animal-sourced foods or restrictive eating habits further depletes iron, zinc, and vitamin A, with evidence linking such patterns to impaired cognitive and immune function independent of overall energy status. Cultural or habitual food taboos that limit diverse intake, particularly in vulnerable groups, sustain these deficiencies despite available interventions.

Socioeconomic and Environmental Factors

Poverty represents a core socioeconomic driver of malnutrition, with undernutrition rates markedly higher in low-income households across global populations. Systematic reviews indicate that absolute economic status inversely correlates with malnutrition prevalence, as resource constraints limit access to sufficient and nutritious food. This relationship manifests in a bidirectional cycle, wherein malnutrition impairs productivity and perpetuates economic disadvantage, while poverty restricts dietary quality and diversity. For instance, children in the lowest wealth quintiles exhibit stunting rates up to three times higher than those in higher quintiles in multiple developing countries. Income inequality exacerbates these disparities, fostering uneven distribution of nutritional resources independent of average malnutrition levels. Studies across developing nations reveal consistent socioeconomic gradients in childhood undernutrition, where Gini coefficients positively associate with inequality in stunting and wasting outcomes. Lower maternal education further compounds risks by hindering awareness of balanced diets and sanitation practices, with evidence from multi-country analyses linking each additional year of schooling to reduced odds of child malnutrition. Rural residence amplifies these effects through limited market access and infrastructure, contrasting with urban areas despite urban poverty pockets. Environmental stressors, particularly climate-induced events like droughts and floods, intensify malnutrition by undermining food production and supply chains. Meta-analyses of child cohorts demonstrate that droughts elevate wasting and stunting risks through crop failures and water scarcity, while floods disrupt sanitation and exacerbate diarrheal diseases that impair nutrient absorption. In vulnerable regions such as sub-Saharan Africa and South Asia, these events have driven spikes in acute malnutrition; for example, prolonged droughts correlate with under-five wasting increases of 20-50% in affected areas. Soil degradation and erratic precipitation patterns further erode agricultural yields, disproportionately impacting subsistence farmers in low-income settings where adaptive capacities remain limited. Socioeconomic vulnerabilities thus interact with environmental pressures, as impoverished communities face heightened exposure and reduced resilience to such disruptions.

Policy Failures and Systemic Critiques

Despite commitments under to achieve zero hunger by 2030, global progress has stalled, with the world far off track as of 2025, exacerbated by conflicts, climate shocks, and economic disruptions that have reversed prior gains in undernourishment reduction. The for 2025 reports only marginal improvement, with hunger levels declining by just 0.7 points since 2016 to 18.3, insufficient to meet targets amid rising acute food insecurity affecting 319 million people in 67 countries. Policy frameworks have failed to integrate responses to these drivers, such as inadequate investment in resilient agriculture and overreliance on short-term emergency aid rather than structural reforms. International food aid programs, often tied to donor surpluses like U.S. commodity exports, have drawn criticism for distorting local markets and fostering dependency in recipient countries, undermining domestic farmers and long-term food security. Empirical reviews indicate mixed development outcomes, with food aid sometimes exacerbating conflicts or providing unreliable insurance against shocks due to inconsistent delivery, rather than building sustainable production capacity. Critics argue that aid alone cannot address root causes like political instability and fragile agricultural systems, as it overlooks incentives for local innovation and often prioritizes donor interests over recipient needs. In high-income nations, agricultural subsidies have systematically favored commodity crops such as corn and soybeans, which are processed into high-calorie, nutrient-poor foods, contributing to the obesity epidemic as a form of overnutrition and malnutrition. U.S. policies under the Farm Bill, for instance, have subsidized these crops disproportionately, lowering their relative prices and correlating with higher consumption of calorie-dense products linked to rising obesity rates exceeding 40% in adults. Such subsidies, intended for food security, instead perpetuate poor dietary patterns by making unhealthy options artificially cheap, while underfunding fruits, vegetables, and nutrient-rich alternatives. Systemic critiques in developing countries highlight failures in social protection systems, which often neglect the interconnected burdens of undernutrition, micronutrient deficiencies, and emerging overnutrition, leading to inefficient targeting and perpetuation of poverty-malnutrition cycles. Policies influenced by international financial institutions, such as structural adjustment programs, have at times prioritized fiscal austerity over nutrition-sensitive investments, correlating with persistent stunting rates affecting 149 million children under five as of 2022. Corruption and conflict further erode aid effectiveness, with underfunding—such as recent cuts to nutrition programs—projected to increase child mortality without integrated health, education, and agricultural reforms. These shortcomings reflect a broader disconnect between policy design and causal factors like urbanization and inequality, where empirical data shows socioeconomic disparities driving uneven malnutrition burdens despite average economic growth.

Clinical Effects and Consequences

Acute Manifestations and Signs

Severe acute malnutrition (SAM) is clinically identified by severe wasting, defined as a weight-for-height z-score below -3 standard deviations or mid-upper arm circumference less than 11.5 cm in children aged 6-59 months, or by the presence of nutritional edema. These manifestations arise rapidly from insufficient caloric or protein intake, often exacerbated by infection or famine, leading to metabolic adaptations like reduced basal metabolic rate and impaired immune function. In marasmus, the predominant form of non-edematous SAM, acute signs include profound muscle wasting and near-total depletion of subcutaneous fat, resulting in a skeletal appearance with loose, wrinkled skin resembling "old man's face." Affected individuals often display apathy, irritability, and a voracious appetite if conscious, alongside hypothermia and bradycardia due to energy conservation. Physical examination reveals diminished gluteal fat pads and axillary muscle mass, with weight loss exceeding 15% in acute episodes. Kwashiorkor, characterized by edematous SAM, presents with bilateral pitting edema beginning in the feet and ankles, progressing to the face and limbs, often masking underlying wasting. Dermatological signs include "flaky paint" or "crazy paving" hyperpigmented lesions on the skin, particularly in pressure areas, alongside sparse, brittle, depigmented hair that easily pulls out. Hepatomegaly from fatty liver infiltration and a profoundly depressed appetite distinguish it from marasmus, with patients showing lethargy and increased susceptibility to infections manifesting as rapid clinical deterioration. Across both forms, acute malnutrition elicits systemic signs such as dry, inelastic skin, oral ulcers, and angular cheilitis from micronutrient deficiencies, particularly zinc and vitamins A and C. Laboratory correlates, though not diagnostic alone, include hypoalbuminemia (below 2.5 g/dL) contributing to edema in kwashiorkor and hypoglycemia in severe cases. These manifestations demand urgent differentiation from dehydration or sepsis, as untreated SAM carries a mortality risk exceeding 20% in complicated cases.

Chronic Health and Developmental Impacts

Chronic malnutrition, particularly during critical periods of growth such as early childhood, results in stunting, defined as height-for-age more than two standard deviations below the median of growth standards, which impairs linear growth and persists into adulthood, limiting physical stature and work capacity. Stunted individuals face heightened risks of non-communicable diseases, including cardiovascular disease, with seven of eight studies on famine-exposed cohorts showing consistent associations between early severe malnutrition and elevated incidence in later life. Additionally, chronic undernutrition compromises lung development, increasing susceptibility to respiratory infections and reducing lung function over time, as evidenced by longitudinal data linking prenatal and early postnatal malnutrition to persistent pulmonary impairments. In terms of immune function, prolonged malnutrition disrupts cellular and humoral immunity, leading to lifelong vulnerability to infections through mechanisms such as thymic atrophy and reduced T-cell production, which perpetuate cycles of recurrent illness and further nutritional depletion. This immune dysregulation contributes to higher mortality from opportunistic infections in adulthood, independent of acute episodes, based on cohort studies tracking undernourished populations. Developmental impacts are profound in children, where malnutrition during the first 1,000 days from conception to age two irreversibly affects brain architecture, resulting in cognitive deficits such as 10-15 point reductions in IQ and impaired executive function, as observed in follow-up studies of severely malnourished infants. These children demonstrate poorer school achievement, behavioral problems, and reduced adaptive skills persisting into adolescence, with meta-analyses confirming associations between early stunting and lower educational attainment. Neuroimaging evidence further reveals structural changes, including smaller brain volumes and altered connectivity, correlating with these functional impairments in adulthood. Beyond cognition, chronic malnutrition elevates risks of metabolic disorders in survivors, including insulin resistance and obesity upon nutritional transitions, due to epigenetic alterations in fetal and early programming that predispose to diabetes and hypertension. Longitudinal Jamaican studies of kwashiorkor survivors, for instance, report persistent developmental delays in motor and social domains into middle childhood, underscoring the causal role of protein-energy deficits in disrupting neuroplasticity. Overall, these effects compound socioeconomic disadvantages, with stunted adults earning up to 20% less due to diminished productivity, as quantified in economic models from low-income cohorts.

Broader Societal and Economic Ramifications

Malnutrition exerts profound economic pressures by diminishing human capital and inflating public expenditures. Preventable undernutrition alone costs the global economy an estimated $761 billion annually, or roughly 1% of world GDP, through mechanisms such as impaired physical growth, cognitive deficits, and reduced labor productivity in affected populations. These losses compound over lifetimes, with stunted children facing 20% lower earnings as adults due to diminished educational outcomes and work capacity. In aggregate, broader malnutrition—including micronutrient deficiencies and diet-related non-communicable diseases—may impose costs exceeding $3.5 trillion yearly, equivalent to $500 per person worldwide, primarily via foregone productivity and elevated healthcare demands. Healthcare systems bear a disproportionate burden, as malnutrition amplifies disease susceptibility and treatment needs. In the United States, disease-associated malnutrition contributes over $15.5 billion annually to direct medical costs, with similar patterns in other nations where undernourished individuals require prolonged hospital stays and interventions for complications like infections or organ failure. Globally, this diverts fiscal resources from infrastructure and education, slowing economic growth; for instance, in low-income countries, malnutrition-linked productivity shortfalls equate to 2-3% of GDP annually, perpetuating underinvestment in development. Overnutrition's parallel effects, such as obesity-driven chronic conditions, further strain budgets, with estimates linking unhealthy diets to 2.2% of global GDP in related health and productivity losses. On the societal front, malnutrition entrenches intergenerational poverty by eroding intellectual and physical capabilities essential for social mobility. Early-life undernutrition correlates with lower school performance and higher dropout rates, reducing societal innovation and adaptability while fostering dependency on welfare systems. This human capital erosion sustains inequality, as malnourished cohorts exhibit heightened vulnerability to non-communicable diseases in adulthood—such as diabetes and cardiovascular issues—exacerbating healthcare inequities and social fragmentation. In regions with acute prevalence, like sub-Saharan Africa and South Asia, these dynamics hinder community resilience, amplifying migration pressures and straining social services without addressing root causal factors like agricultural inefficiencies or policy shortcomings. Empirical analyses underscore that while economic growth can mitigate some effects, persistent malnutrition independently retards progress by impairing workforce quality and institutional stability.

Prevention Strategies

Individual and Community-Based Measures

Individual measures to prevent malnutrition emphasize behavioral practices grounded in nutritional science, such as exclusive breastfeeding for infants up to six months, which reduces the risk of stunting, wasting, and underweight by providing optimal nutrient density and immune protection without introducing contaminants that could lead to infections exacerbating nutrient loss. Promotion of timely introduction of diverse, nutrient-rich complementary foods after six months, combined with continued breastfeeding up to two years or beyond, further mitigates micronutrient deficiencies and growth faltering, as evidenced by longitudinal studies in low-income settings showing sustained height-for-age improvements. Personal hygiene practices, including handwashing with soap before food preparation and consumption, handwashing after defecation, and safe water storage, interrupt fecal-oral transmission of pathogens that cause diarrhea—a primary driver of acute malnutrition through malabsorption and increased metabolic demands—though randomized trials indicate these yield indirect rather than direct reductions in wasting prevalence. At the community level, nutrition education programs delivered through peer-led groups or health worker outreach have demonstrated effectiveness in enhancing dietary diversity and caregiving knowledge, leading to measurable declines in undernutrition indicators among children under five; a systematic review of interventions in developing countries found consistent improvements in weight-for-age and height-for-age z-scores, with effect sizes amplified in programs lasting 12-24 months that incorporate behavior change communication on local food utilization. Community mobilization for hygiene and sanitation, such as latrine construction and chlorination of water sources, supports these efforts by curbing infection rates that compound caloric deficits, with observational data linking improved WASH access to lower diarrhea incidence and better nutrient retention, despite limited causal evidence from cluster trials directly tying such interventions to stunting prevention. Integrated community strategies, blending individual counseling with collective action like women's groups promoting home fortification of staples or seasonal food preservation, address barriers to access in resource-constrained areas; evaluations in sub-Saharan Africa report up to 15% reductions in stunting prevalence attributable to such multifaceted approaches, which prioritize causal pathways like enhanced maternal knowledge over isolated inputs. These measures prove most impactful when tailored to local epidemiology, avoiding one-size-fits-all models that overlook behavioral determinants, and empirical outcomes underscore the need for sustained monitoring to counter relapse risks from socioeconomic volatility.

Agricultural and Food System Interventions

Nutrition-sensitive agriculture (NSA) interventions, which incorporate nutritional objectives into farming systems such as homestead food production and livestock integration, have been associated with enhanced dietary diversity and reduced incidence of child wasting and underweight in randomized trials across low-income settings. A systematic review of 41 studies found that NSA approaches improved women's and children's diets, with effect sizes indicating up to 0.2-0.3 standard deviation gains in dietary quality scores, though impacts on anthropometric outcomes like stunting were inconsistent due to confounding factors such as sanitation and maternal education. These interventions succeed by promoting year-round access to micronutrient-rich produce, but their efficacy diminishes in contexts of market dependency or climate variability, where staple crop reliance persists. Biofortification, involving conventional breeding or agronomic enhancement to increase crop micronutrient density, addresses "hidden hunger" by delivering bioavailable nutrients through staple foods consumed regularly. Meta-analyses of iron-biofortified crops, including pearl millet and beans, report significant improvements in hemoglobin levels (by 0.9-1.5 g/dL) and cognitive function in school-aged children after 4-6 months of consumption, with similar zinc biofortification yielding 10-20% reductions in deficiency prevalence in cereal-dependent populations. Provitamin A biofortified sweet potatoes and maize have reduced vitamin A deficiency rates by 15-30% in intervention groups in Africa and Asia, as evidenced by randomized controlled trials measuring serum retinol. While cost-effective at $0.25-1.00 per beneficiary annually compared to supplementation, adoption barriers include farmer acceptance and regulatory hurdles for genetically modified variants like Golden Rice, which has faced delays despite potential to avert 500,000 annual blindness cases from vitamin A shortfall. Crop diversification strategies, shifting from monoculture staples to mixed systems including legumes, vegetables, and fruits, correlate with improved household nutrition security in panel data from sub-Saharan Africa. In Uganda, adopting diversification increased dietary diversity scores by 1-2 points on a 12-point scale and reduced child stunting odds by 20-25%, mediated by higher own-production consumption rather than market sales. Cross-national analyses show a saturating positive relationship between national crop diversity indices and nutritional stability, with diversified systems buffering against price shocks and yield failures, though gains plateau beyond 5-7 crop types per farm. Empirical evidence from Ethiopia indicates modest height-for-age z-score improvements (0.1-0.2 SD) in diversified households, but effects are heterogeneous, stronger among subsistence farmers than commercial ones. Reducing post-harvest losses through improved storage, drying, and transport preserves up to 20-30% of caloric and nutrient value lost annually in developing countries, directly bolstering food availability for malnutrition-prone groups. Hermetic storage bags and metal silos have cut grain losses by 80-90% in trials across Africa, correlating with 10-15% higher household nutrient intakes and lower undernutrition rates in maize-dependent regions. In fruits and vegetables, cold chain interventions and timely harvesting reduce vitamin C and folate degradation by 50%, potentially averting micronutrient gaps equivalent to feeding 100 million additional people, though implementation costs and infrastructure gaps limit scalability in rural areas. Overall, these food system measures complement but do not fully supplant demand-side factors, with rigorous evaluations underscoring the need for integrated approaches to achieve sustained undernutrition declines.

Policy Frameworks and Empirical Critiques

The United Nations Sustainable Development Goal 2 (SDG 2), adopted in 2015, aims to end hunger, achieve food security, improve nutrition, and promote sustainable agriculture by 2030, including specific targets to reduce stunting and wasting in children under five and address malnutrition in all forms. Complementary frameworks include the World Health Organization's (WHO) Global Nutrition Targets for 2025, which seek a 40% reduction in child stunting, 50% reduction in anemia among women of reproductive age, and 30% reduction in low birth weight, among others. The UNICEF-led Global Action Plan on Child Wasting targets reducing wasting prevalence to below 5% by 2025 and 3% by 2030 through multisectoral interventions focusing on maternal health, food access, and health systems. These policies emphasize integrated approaches, including fortification, supplementation, and agricultural investments, often coordinated via international bodies like the (WFP), which prioritizes prevention in humanitarian contexts. Empirical data reveals substantial shortfalls in achieving these targets, with global undernourishment rising from 8.0% in 2019 to 9.2% in 2022, affecting 735 million people, reversing prior declines and marking the world as far off-track for SDG 2. Projections indicate that by 2030, undernourishment will persist at levels exceeding pre-2015 reductions, with only limited progress in select indicators like child wasting in some regions, while stunting affects 149 million children as of 2022. For WHO targets, modeling from 2021 data shows few countries on pace to meet even one of the six core goals by 2025 or 2030, with global stunting reductions lagging at under 20% since 2012 and anemia prevalence unchanged at around 30% in women.02180-9/abstract) These failures correlate with external shocks like the COVID-19 pandemic, conflicts, and economic disruptions, but also highlight implementation gaps, as funding for nutrition-sensitive agriculture remains below 20% of official development assistance in many cases. Critiques of these frameworks center on their limited causal impact, often prioritizing symptom alleviation through aid and supplementation over addressing root drivers such as population growth outpacing food production in high-burden regions and governance failures enabling aid diversion. Scoping reviews of food system policies, including subsidies and taxes, indicate modest effects on consumption patterns but negligible broad-scale reductions in malnutrition rates, with fiscal interventions like sugar taxes yielding only 10-30% drops in targeted purchases without sustained nutritional improvements. Moreover, international targets have faced criticism for overreliance on voluntary commitments and insufficient enforcement, leading to "polycrisis" amplification where policy silos fail to integrate economic reforms or trade policies that could enhance local production resilience. Empirical analyses underscore that despite trillions in global aid since 2000, hunger levels have stagnated or worsened in sub-Saharan Africa and South Asia, suggesting systemic inefficiencies including corruption in recipient states and misaligned incentives in donor programming. These shortcomings necessitate reevaluation toward evidence-based shifts, such as prioritizing high-yield agricultural innovations over redistributive measures with proven low returns on investment.

Treatment Approaches

Nutritional Supplementation and Rehabilitation

Nutritional rehabilitation for severe acute malnutrition (SAM) follows phased protocols to stabilize metabolism and promote weight gain, beginning with inpatient care for complicated cases involving edema or medical instability. The World Health Organization recommends an initial stabilization phase using F-75 formula, providing 80-100 kcal/kg/day with low protein to avoid refeeding syndrome, characterized by hypophosphatemia, hypokalemia, and fluid shifts due to rapid carbohydrate metabolism shifts in starved patients. Electrolytes like potassium and magnesium are supplemented prophylactically, with monitoring every 12 hours initially to replete deficiencies and prevent cardiac or respiratory complications. Transition to F-100 formula or ready-to-use therapeutic food (RUTF) follows, delivering 150-220 kcal/kg/day for rehabilitation, alongside routine vitamin A, zinc, and folic acid supplementation to address common deficits. For uncomplicated SAM, community-based management of acute malnutrition (CMAM) shifts treatment to outpatient settings, distributing RUTF—peanut-based pastes fortified with micronutrients—for home use after screening via mid-upper arm circumference. Programs report recovery rates of 76-85%, with mortality below 5% and default rates under 15%, outperforming facility-based approaches in accessibility and cost. RUTF trials demonstrate noninferiority of reduced doses for weight velocity and recovery, suggesting flexibility in resource-limited contexts without compromising outcomes like weight-for-height z-score improvements. In moderate acute malnutrition (MAM), ready-to-use supplementary foods (RUSF) or fortified blends support outpatient recovery, though evidence indicates variable efficacy tied to adherence and local diet quality. Rehabilitation emphasizes gradual caloric escalation to mitigate refeeding risks, with thiamine supplementation (200-300 mg pre-refeeding) essential to prevent in depleted states. Empirical data from CMAM implementations in Africa show sustained gains, with 85-91% cure rates in outpatient therapeutic programs, though defaulters and non-responders highlight needs for enhanced follow-up. Overall, these interventions reduce SAM mortality by addressing caloric deficits causally linked to organ failure, yet program success depends on supply chain reliability and caregiver compliance.

Medical Management Protocols

Medical management of severe acute malnutrition (SAM) in children adheres to World Health Organization (WHO) protocols that prioritize stabilization of metabolic imbalances and complications before nutritional rehabilitation to minimize mortality risks, which can exceed 10-20% without intervention. The approach divides into phases: initial stabilization (days 1-7), transition, and rehabilitation, with inpatient care for complicated cases involving edema, anorexia, or infections, and outpatient management for uncomplicated SAM using ready-to-use therapeutic foods (RUTF). Routine practices include daily monitoring of weight, edema, appetite, and vital signs, alongside empirical broad-spectrum antibiotics such as amoxicillin (50-100 mg/kg/day) to address presumed infections, given that up to 50% of SAM cases present with bacteremia. Key complications demand immediate correction: hypoglycemia (blood glucose <54 mg/dL) is treated with 2 mL/kg of 10% dextrose intravenously or orally if conscious, followed by feeding every 2-3 hours to prevent recurrence. Hypothermia (<35.5°C) is managed through passive rewarming via skin-to-skin contact, clothing, and a warm environment, avoiding rapid external heating to prevent shock. Dehydration, often overestimated in SAM due to depleted extracellular fluid, uses specialized ReSoMal solution (formula adjusted for low sodium and potassium) at 5-10 mL/kg/hour orally or via nasogastric tube for 8-12 hours, with intravenous fluids reserved for shock at 15 mL/kg boluses of Ringer's lactate. Overly aggressive rehydration risks fluid overload and cardiac failure, as evidenced by clinical trials showing higher mortality with standard intravenous protocols. Nutritional initiation employs F-75 formula (75 kcal/100 mL) at 100 kcal/kg/day in 8-12 feeds to stabilize without overload, transitioning to F-100 (100 kcal/100 mL) or RUTF at 150-200 kcal/kg/day for weight gain of 10-20 g/kg/day. Refeeding syndrome—characterized by hypophosphatemia, hypokalemia, and fluid shifts—is mitigated by starting at 50-75% of energy needs, supplementing electrolytes (potassium 3-4 mmol/kg/day, magnesium 0.3-0.6 mmol/kg/day), and monitoring phosphate levels daily during the first week, with thiamine 1-2 mg/kg to prevent Wernicke's encephalopathy. Micronutrient deficiencies are addressed routinely: vitamin A (200,000 IU for children >12 months on day 1, repeated biweekly), (20 mg/day for 10-14 days), and folic acid (1 mg/day), as these reduce mortality by 23-30% in supplemented cohorts per randomized trials. For moderate acute malnutrition or chronic undernutrition without acute complications, protocols emphasize outpatient supplementation with corn-soy blends or lipid-based supplements alongside treatment of infections and parasites, aiming for sustained growth velocity through fortnightly follow-up. In adults or elderly patients with comorbidities such as cancer experiencing significant weight loss and cachexia, urgent nutritional assessment is recommended, prioritizing high-calorie oral nutritional supplements and considering enteral feeding via nasogastric (NG) tube if oral intake is inadequate, particularly with concurrent respiratory issues, as malnutrition impairs respiratory muscle strength and worsens outcomes. Similar principles apply, adapting enteral feeds at 20-25 kcal/kg/day and escalating slowly while screening for via and albumin trends. Recovery criteria include weight-for-height z-score >-2, no , and full appetite, with discharge followed by preventive rations to curb relapse rates of 5-10%.

Implementation Challenges and Outcomes

Implementation of malnutrition treatment protocols, particularly community-based management of acute malnutrition (CMAM) using ready-to-use therapeutic food (RUTF), encounters significant logistical barriers in low-resource settings, including inconsistent supply chains for RUTF and essential antibiotics, which lead to treatment interruptions and inappropriate usage. In regions like southern , inadequate provision of RUTF has resulted in program exits without full recovery, exacerbating relapse risks. Human resource constraints, such as shortages of trained personnel and poor clinical skills in anthropometric assessments, contribute to diagnostic discrepancies and delayed interventions for severe acute malnutrition (SAM). Conflict, poverty, and geographic inaccessibility in low-income countries further hinder access, with and ineffective food systems compounding these issues. Despite these obstacles, CMAM programs have demonstrated measurable outcomes, with recovery rates for uncomplicated SAM often exceeding 80% when supplies and adherence are maintained; for instance, in Indian programs, 88.4% of non-defaulters achieved cure with an average of 4.9 g/kg/day. RUTF-based home therapy has yielded higher recovery rates (e.g., weight-for-height Z-score > -2) compared to standard inpatient care in , though relapse remains a concern without sustained follow-up. Overall mortality reductions are evident in Eastern and Southern African national CMAM implementations, averting deaths through scaled outpatient care, yet default rates (up to 6.7%) and variable death rates (around 5.9% in some cohorts) underscore the impact of implementation gaps. In , RUTF programs achieved 95% recovery amid disruptions, highlighting potential efficacy when integrated with community screening.

Historical Development

Early Observations and Conceptualizations

Observations of malnutrition symptoms date back to ancient civilizations, where dietary insufficiencies were noted without full causal understanding. In around 1550 BC, records described conditions resembling , characterized by bleeding gums and weakness among those with limited fresh produce access. Similarly, Egyptian texts from the same era documented night blindness treated effectively with liver consumption, an empirical remedy later attributable to precursors, though conceptualized then through trial-and-error rather than . , in the 5th century BC, linked poor diet to health declines, observing dropsy and as consequences of inadequate intake, framing within humoral theory where imbalances in bodily fluids stemmed from food quality and quantity. By the medieval period, malnutrition manifestations appeared in skeletal remains, indicating chronic childhood undernutrition that impaired bone development and heightened infection susceptibility, though contemporary accounts rarely isolated nutritional causes from or plague. In , emerged prominently in the 17th century amid , with Daniel Whistler providing a detailed clinical description in 1645, attributing deformed bones and delayed growth to "vitiated air" in crowded cities rather than specific deficiencies. Francis Glisson expanded this in 1650, documenting rachitic symptoms like bowed legs and cranial softening in English children, hypothesizing environmental factors over dietary ones, as fresh and were inconsistently linked to prevention. These observations marked initial steps toward recognizing environmental-dietary interactions in skeletal disorders. The 18th century advanced empirical testing, exemplified by James Lind's 1747 controlled trial aboard HMS Salisbury, where he divided 12 scurvy-afflicted sailors into groups receiving varied remedies, finding citrus fruits () rapidly alleviated symptoms like and gingival hemorrhage, contrasting ineffective treatments such as or . Lind's 1753 treatise conceptualized as arising from dietary or lack of "fresh vegetable acids," challenging prevailing miasma theories and advocating antiscorbutics, though adoption lagged due to logistical naval constraints. In , beriberi—a neuropathy with and —plagued polished--dependent populations; Christiaan Eijkman's late-19th-century experiments (starting 1886) on chickens revealed polyneuritis from milled , reversed by , suggesting a protective "substance" absent in refining, a precursor to deficiency models. These early efforts shifted conceptualizations from mystical or infectious etiologies toward nutritional causality, emphasizing preventable lacks in specific foods over generalized , though full paradigms awaited 20th-century biochemistry. Empirical remedies preceded theory, with causal realism emerging via controlled observations that prioritized dietary interventions' outcomes over doctrinal adherence.

20th-Century Advances and Responses

Early 20th-century research established the biochemical basis of deficiencies as a primary form of malnutrition, with discoveries linking specific vitamins to diseases like beriberi, , and . Christiaan Eijkman's experiments in the demonstrated that polished caused beriberi in chickens, attributing it to a missing dietary factor rather than , earning him the 1929 in Physiology or Medicine shared with Frederick Hopkins. coined the term "vitamine" in 1912 to describe these essential substances preventing deficiency diseases, synthesizing knowledge from studies on and other conditions. Albert Szent-Györgyi's isolation of ascorbic acid () in 1932 explained scurvy's , enabling targeted prevention through fruits or supplements. These findings shifted paradigms from caloric sufficiency to qualitative nutritional balance, informing campaigns like in to combat rickets in industrialized nations. Mid-century advances focused on protein-energy malnutrition (PEM), distinguishing conditions like and . Cicely Williams first described in 1933 among Ghanaian children, characterizing it as and fatty liver from protein deficiency post-weaning, despite adequate calories from starchy diets. Post-World War II, agencies prioritized PEM as a global crisis, with FAO estimating chronic undernourishment affecting over 60 million by the early 1990s, though interventions reduced prevalence from 12% productivity losses in 1900 to 6% by 2000. WHO's 1960s efforts during African famines classified PEM's medical consequences, promoting high-protein foods and rehabilitation protocols. International responses included FAO's 1945 founding to defeat hunger through agricultural development and UNICEF's milk distribution programs, which addressed protein gaps in developing regions from the 1950s to 1970s. Public health responses emphasized and supplementation, yielding measurable declines in deficiencies. In the United States, FDA-mandated enrichment of grains with from the 1940s eradicated , while iodized salt programs post-1920s reduced goiter prevalence by over 90% in affected areas. Globally, WHO and FAO coordinated initiatives, such as supplementation trials in the 1970s, which later proved effective in reducing . The Green Revolution's high-yield crops from the , supported by FAO, boosted production and mitigated risks, though PEM focus waned by the 1970s as energy deficits overshadowed protein concerns. These empirical interventions, grounded in controlled trials and biochemical assays, demonstrated causal links between targeted and outcomes, contrasting with earlier anecdotal approaches.

Contemporary Shifts and Ongoing Debates

In the early , the understanding of malnutrition shifted from a primary focus on undernutrition and protein-energy deficits toward a multifaceted framework incorporating deficiencies, diet quality, and , recognizing the "double burden" where undernutrition and coexist in populations, particularly in low- and middle-income countries undergoing nutritional transitions. This evolution reflects empirical observations of dietary shifts driven by , processed food availability, and economic changes, with global undernourishment affecting 9.2% of the in 2020–2022, up from pre-2015 declines. Progress toward UN (zero hunger by 2030) has stalled, as evidenced by projections indicating persistent high levels of undernourishment despite earlier reductions from 23% in 2000 to 14.5% in 2012. Ongoing debates center on the relative efficacy of nutrition-specific interventions, such as supplementation and , versus nutrition-sensitive approaches addressing underlying determinants like , , and . Critics argue that an overemphasis on agency and individual behaviors, influenced by neoliberal policies, neglects structural factors such as conflict, variability, and inequitable food systems, which exacerbated malnutrition during events like the COVID-19 pandemic and recent wars. For instance, acute malnutrition programs prioritize ready-to-use therapeutic foods for severe cases, while chronic malnutrition strategies emphasize preventive dietary diversity, yet divergences in implementation hinder integrated responses. A key contention involves the reframing of malnutrition classifications, with some scholars critiquing the tripartite model (undernutrition, deficiencies, /) for oversimplifying causal pathways and underrepresenting diet-related non-communicable diseases. Empirical data highlight rising diet-related mortality, prompting calls for policy prioritization of nutrient-dense, whole-food diets over processed alternatives, though debates persist on the scalability of such shifts amid global constraints. Additionally, issues arise, as institutional reports from bodies like the WHO and FAO, while data-rich, often reflect coordinated agendas that may downplay failures in aid effectiveness or agricultural subsidies' roles in perpetuating imbalances. These debates underscore the need for causal analyses prioritizing empirical outcomes over ideological narratives in intervention design.

Special Populations

Children and Adolescents

Children under five years of age bear a disproportionate burden of global undernutrition, with 23.2% stunted (149 million) and 6.8% wasted (45 million) in 2022, figures that persisted into 2024 despite modest declines. Stunting, reflecting chronic malnutrition, correlates with linear growth failure due to prolonged nutrient deficits and recurrent infections, while wasting indicates acute energy deficits often exacerbated by diarrhea or fever. Underweight prevalence, combining both forms, affects millions, though exact global figures vary by region, with highest rates in South Asia and sub-Saharan Africa. Adolescents experience a "double burden," with undernutrition (e.g., anemia, stunting persistence) coexisting alongside rising overweight/obesity rates of 8.1% to 37%, driven by dietary shifts in low- and middle-income countries. Risk factors for malnutrition in this age group include household , low maternal , large family sizes, short birth intervals, and inadequate , which amplify risks and nutrient absorption barriers. In children, suboptimal and complementary feeding practices contribute causally, as exclusive breastfeeding for six months reduces risk by supporting immune and gut health. For adolescents, , poor dietary diversity, and cultural norms limiting girls' access to nutrient-dense s heighten vulnerability, particularly to during growth spurts and menstruation. Empirical data link these factors to higher odds of stunting (e.g., odds ratios 1.5–3.0 for low maternal ) and underscore causal pathways via reduced access and repeated illnesses. Immediate consequences encompass heightened mortality—45% of under-five deaths link to undernutrition—and impaired immunity, increasing susceptibility by 2–10 fold. Long-term, childhood stunting forecasts adolescent and adult deficits: reduced (persisting into teens), cognitive impairments (e.g., 5–10 IQ point losses), lower , and elevated risk (88% of studies confirm). Peer-reviewed cohorts from and reveal survivors exhibit persistent physical weakness, diminished accumulation, and metabolic vulnerabilities into adulthood. Overnutrition in adolescents correlates with early non-communicable diseases, compounding undernutrition's legacy. Effective interventions prioritize prevention: promoting exclusive halves under-five mortality from malnutrition-related causes, while small-quantity lipid-based nutrient supplements for ages 6–23 months improve growth and reduce . For severe acute malnutrition, community-based therapeutic feeding with ready-to-use therapeutic foods achieves 90% recovery rates when accessible, though implementation gaps in low-resource settings limit impact. Adolescent programs emphasizing dietary education and fortification (e.g., iron for girls) show moderate efficacy in curbing , yet require integration with alleviation for sustained causal effects. Challenges persist, as only 28% of countries are on track to halve stunting by 2030, highlighting needs for scaled, evidence-based actions over unproven aid models.

Reproductive-Age Women

Malnutrition among reproductive-age women, typically defined as those aged 15-49 years, manifests primarily as undernutrition, deficiencies, and the double burden of concurrent and /, exacerbating risks during conception and . Globally, anaemia affects approximately 605 million women in this demographic, representing 31% of the total, with as the predominant cause due to inadequate dietary intake and increased physiological demands. The double burden, including combined with anaemia or / with anaemia, prevailed at 24.1% in 2021, reflecting a decline from prior years but persistent challenges in low- and middle-income countries where dietary diversity remains limited. Undernutrition in this group impairs ovarian function and oocyte maturation, contributing to reduced and higher rates of secondary , as evidenced by associations in East African populations where low correlates with ovulatory dysfunction. During , maternal malnutrition elevates risks of adverse outcomes, including preterm delivery, low birth weight infants, , and , with anaemia specifically linked to increased maternal and neonatal mortality. These effects stem from causal mechanisms such as depleted energy reserves disrupting hormonal balance and fetal nutrient supply, leading to . Critical deficiencies compound these vulnerabilities: iron shortfall drives anaemia prevalence, while inadequacy heightens risks in offspring, necessitating 400 micrograms daily intake preconceptionally. and deficiencies, prevalent in up to 61% and 40% of women in certain cohorts, further impair immune function and placental development, respectively. In regions like southern and , where over 50% of women may face multiple deficiencies, intergenerational transmission occurs as malnourished mothers bear stunted or low-weight children, perpetuating cycles of impaired growth and . Interventions targeting preconceptional , such as iron-folate supplementation, have demonstrated reductions in anaemia by up to 50% in trial settings, underscoring the need for sustained dietary improvements over episodic aid.

Elderly and Institutionalized Groups

Malnutrition affects a substantial portion of the , with a global pooled prevalence of approximately 18.3% among older adults, and nearly half at risk, based on meta-analyses of screening tools like the Mini Nutritional Assessment. In 2021, over 97.6 million cases were reported worldwide, marking a 1.2-fold increase from 1990 levels, driven by aging demographics and comorbidities. In the United States, estimates indicate that around 25% of older adults are malnourished or at nutritional risk, with prevalence escalating in settings like hospitals (up to 50%) and nursing homes. Among institutionalized elderly, such as those in nursing homes and facilities, malnutrition rates are notably higher, ranging from 23% to 60%, influenced by institutional environments independent of individual health factors. Contributing causes include age-related physiological declines—such as diminished , impaired nutrient absorption, and —compounded by chronic diseases, , and dependency for feeding. In care settings, additional risks stem from inadequate staffing levels, insufficient individualized care plans, high turnover of aides, poor food quality or palatability, and occasional neglect leading to missed meals or improper assistance. Behavioral and environmental factors, like or institutional routines that limit meal flexibility, further exacerbate undernutrition, often prioritizing protein-energy deficits over imbalances. Consequences in these groups are severe, including accelerated functional decline, increased susceptibility to infections, delayed , and heightened fall risk, all linked to muscle wasting and immune suppression. Malnourished elderly in institutions face elevated mortality rates, prolonged recovery from illnesses, and greater healthcare utilization, with studies showing associations between poor nutritional status and adverse outcomes like higher ICU admissions and ventilation needs. Early screening via validated tools and targeted interventions, such as fortified diets or oral supplements, can mitigate these effects, though implementation varies due to resource constraints in understaffed facilities.

References

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