The U.S. Food and Drug Administration (FDA) defines supplements as products that contain micronutrients in concentrated form that are intended to add further nutritional value to the diet. Supplementation formulations include tablets, capsules, softgels, gelcaps, liquids, or powders, and they can be consumed alone or combined with foods.

Oral iron supplements are the first-line treatment for iron deficiency and iron deficiency anemia in women of reproductive age. Gastrointestinal side effects from iron supplement intake are commonly reported, but can be decreased by following proper dosing regimens. Supplements containing iron may have a negative impact on the pediatric gut microbiome, but these adverse effects may be reduced with the addition of prebiotics.

In areas with a high burden of viral, parasitic, and/or bacterial infections, aiming supplementation at children who are anemic or at risk of iron deficiency is suggested, accompanied by malaria prevention and disease treatment strategies. Vitamin A supplementation can improve hemoglobin concentrations.