Simple diets based on staple foods with little variation are often deficient in certain nutrients, either because they are not present in sufficient amounts in the soil of a region, or because of the inherent inadequacy of the diet. Addition of micronutrients to staples and condiments can prevent large-scale deficiency diseases in these cases.
Folic acid is added to flour in many industrialized countries, and has prevented a significant number of neural tube defects in infants. It is, however, not uniform in its application, with more intake of folic acid through fortified flour among those who were already receiving high amounts through their diet.
Calcium is frequently added to fruit juices, carbonated beverages and rice.
A wide range of iron compounds, including ferrous sulfate, ferrous fumarate and even elemental iron powder are added to food (usually cereal flours, but also table salt, milk and condiments) in a number of countries to prevent iron deficiency anemia. Although iron intake is often sufficient in developing countries, the bioavailability of the dietary iron is low, due to such factors as polyphenols and phytic acid binding the iron and preventing its absorption. Major challenges in iron fortification are to avoid undesirable changes in the appearance and taste of the food, and to target the population segment that needs the fortification the most. The fortification of foodstuffs with iron is considered an unethical form of mass medication by many doctors. While it may benefit some, others already have excessive iron stores — iron overload (hyperferremia) — a condition affecting most males over 35, and far more common and more serious than hypoferremia. Anemia is not lack of iron, but lack of iron-containing hemoglobin in the blood; some anemias are actually iron-loading. A far safer anti-anemia supplementation would be vitamin C, which increases the absorption of iron. Iron has been identified as exacerbating many conditions, including acute myocardial infarct and vitamin tablets without iron are now available for men.