Why does the FDA require that certain foods be fortified with niacin?

The Food and Drug Administration (FDA) requires the addition of certain micronutrients to processed grain foods such as breads, corn meal, flour, macaroni and rice to compensate for the loss of these nutrients during flour bleaching and processing. The typical micronutrients added to enrich cereal grains are thiamin, riboflavin, niacin, iron and folic acid. For niacin, the legally required enrichment amount is 15-34 mg/pound, which provides 8-15% of the adult daily value per serving, depending on the food. Breakfast cereals are often fortified to much higher levels, up to 100% of the adult daily value for niacin in a single serving.