Human nutrition deals with the provision of essential nutrients in food that are necessary to support human life and good health. Poor nutrition is a chronic problem often linked to poverty, food security, or a poor understanding of nutritional requirements. Malnutrition and its consequences are large contributors to deaths, physical deformities, and disabilities worldwide. Good nutrition is necessary for children to grow physically and mentally, and for normal human biological development.

The Recommended Dietary Allowances (RDAs) are scientifically determined levels of essential nutrient intake, deemed sufficient by the Food and Nutrition Board to meet the nutritional needs of nearly all healthy individuals.

The first RDAs were published in 1943, during World War II, with the aim of setting standards for optimal nutrition. The initial editions outlined daily nutrient recommendations for various age groups, reflecting the latest scientific insights at the time (NRC, 1943). The history and evolution of the RDAs have been extensively detailed by the chair of the first Committee on Recommended Dietary Allowances (Roberts, 1958). Over the years, the RDAs have been periodically updated, with the current version being the tenth edition.

Originally intended to address nutrition issues related to national defense, the RDAs now serve multiple roles, including guiding food supply planning for population groups, interpreting dietary intake data, establishing standards for food assistance programs, assessing the nutritional adequacy of food supplies, designing nutrition education initiatives, aiding in the development of new food products, and setting guidelines for food labeling. However, the data underpinning these nutrient requirement estimates are often limited.

The nutritional requirements system adopted by the United States and Canada refers to Dietary Reference Intake (DRI). The DRI is a set of nutritional guidelines developed by the National Academy of Medicine (NAM), part of the National Academies in the United States. Established in 1997, the DRI was created to expand upon the previous standards known as the Recommended Dietary Allowances (RDAs). Unlike the RDAs, the DRI encompasses a broader range of nutritional recommendations. The DRI values are distinct from those found on food and dietary supplement labels in the U.S. and Canada, which use Reference Daily Intakes (RDIs) and Daily Values (%). These labeling standards were originally based on RDAs from 1968 but were updated in 2016.

Dietary Reference Values (DRVs) represent the nutritional standards set by the United Kingdom's Department of Health and the European Food Safety Authority (EFSA) for assessing and planning dietary intakes. The UK's Department of Health introduced these guidelines in 1991 with the publication of Dietary Reference Values for Food Energy and Nutrients for the United Kingdom. This document provides recommended nutrient intakes for the UK population, offering a framework for ensuring adequate nutrition.

DRVs are categorized into three main types: Reference Nutrient Intake (RNI), which covers the nutritional needs of 95% of the population; Estimated Average Requirement (EAR), meeting the needs of 50%; and Lower Recommended Nutritional Intake (LRNI), which addresses the requirements of 5% of the population. These categories help to tailor dietary recommendations to different segments of the population, ensuring a more personalized approach to nutrition.

The seven major classes of nutrients are carbohydrates, fats, fiber, minerals, proteins, vitamins, and water. Nutrients can be grouped as either macronutrients or micronutrients (needed in small quantities). Carbohydrates, fats, and proteins are macronutrients, and provide energy. Water and fiber are macronutrients, but do not provide energy. The micronutrients are minerals and vitamins.