Also called riboflavin, vitamin B-2 converts glucose to energy; may help prevent migraine headaches and cataracts; converts other B vitamins into forms the body can use; is essential for normal cell function and growth; and helps protect against free radical damage. Free radicals are molecules made in the body that can damage cells and may play a role in cancer, heart disease and aging

How Much: Recommended dietary allowance (RDA) = 1.3 mg daily for men; 1.1 mg daily for women.

Too Much:  A tolerable upper limit (UL) has not been determined.

Too Little: Deficiency is rare in a typical U.S. diet. However, malabsorption can occur with diseases such as alcoholism, celiac sprue and certain malignancies.  

Foods: Calf liver; yogurt, milk, eggs; fortified grains and cereals; spinach; and broccoli.

Interactions: Some drying medications or anticholinergic drugs; antidepressants; anti-seizure medications; methotrexate; and probenecid.

Research Note:  Vitamin B-2 helps change vitamins B-6 and folate into usable forms for the body. Methotrexate and the anti-gout medication probenecid (Benemid) may interfere with absorption of B2, although to what degree is in debate.