Food fortification is the addition of micronutrients (essential trace elements and vitamins) to food products. Food enrichment specifically means adding back nutrients lost during food processing, while fortification includes adding nutrients not naturally present. Food manufacturers and governments have used these practices since the 1920s to help prevent nutrient deficiencies in populations. Common nutrient deficiencies in a region often result from local soil conditions or limitations of staple foods. The addition of micronutrients to staples and condiments can prevent large-scale deficiency diseases in these cases.

Food fortification has been identified as the second strategy of four by the WHO and FAO to begin decreasing the incidence of nutrient deficiencies at the global level. As outlined by the FAO, the most commonly fortified foods are cereals and cereal-based products; milk and dairy products; fats and oils; accessory food items; tea and other beverages; and infant formulas. Undernutrition and nutrient deficiency is estimated globally to cause the deaths of between 3 and 5 million people per year.

Fortification is present in common food items in two different ways: adding back and addition. Flour loses nutritional value due to the way grains are processed; enriched flour has iron, folic acid, niacin, riboflavin, and thiamine added back to it. Conversely, other fortified foods have micronutrients added to them that don't naturally occur in those substances. An example of this is orange juice, which often is sold with added calcium.

Food fortification can also be categorized according to the stage of addition:

Micronutrients serve an important role in bodily development and growth. Deficiencies of these micronutrients may cause improper development or even disease.

The WHO and FAO, among many other nationally recognized organizations, have recognized that there are over 2 billion people worldwide who have a variety of micronutrient deficiencies. In 1992, 159 countries pledged at the FAO/WHO International Conference on Nutrition to make efforts to help combat these issues of micronutrient deficiencies, highlighting the importance of decreasing the number of those with iodine, vitamin A, and iron deficiencies. A significant statistic that led to these efforts was the discovery that approximately 1 in 3 people worldwide were at risk for either an iodine, vitamin A, or iron deficiency. Although it is recognized that food fortification alone will not combat this deficiency, it is a step towards reducing the prevalence of these deficiencies and their associated health conditions.

In Canada, the Food and Drug Regulations have outlined specific criteria which justify food fortification:

There are also several advantages to approaching nutrient deficiencies among populations via food fortification as opposed to other methods. These may include, but are not limited to: treating a population without specific dietary interventions therefore not requiring a change in dietary patterns, continuous delivery of the nutrient, does not require individual compliance, and potential to maintain nutrient stores more efficiently if consumed regularly.