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Vitamins, Minerals and Dietary Supplements

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Vitamin B2 (Riboflavin)

What is vitamin B2?

Also known as riboflavin, vitamin B2 is a water-soluble vitamin. Since it is not stored in body fat, after the body uses what it needs, any excess vitamin B2 is excreted in urine or sweat.

Why do we need it?

Vitamin B2 works with the other B vitamins in maintaining body growth and the production of red blood cells. Like thiamin, it helps metabolize carbohydrates into energy. Some studies have shown that vitamin B2 may protect against cataracts, migraine headaches and sickle cell anemia.

How much vitamin B2 should I take?

According to the National Academy of Sciences, the recommended daily allowance (RDA) for riboflavin is as follows:

  • Adult men: 1.7 milligrams/day
  • Adult women: 1.3 milligrams/day
  • Children aged 7-10: 1.2 milligrams/day
  • Infants: 0.5 milligrams/day
  • Pregnant/lactating women: 1.8 milligrams/day

What are some good sources of vitamin B2?

Large amounts of riboflavin can be found in lean meats, fortified cereals and yogurt. Other good sources include milk, cheese, eggs, broccoli and spinach. Because riboflavin is destroyed by exposure to light, foods that contain riboflavin should not be stored in glass containers that are exposed to light.

What can happen if I don't get enough vitamin B2?

Because riboflavin is so plentiful in the average diet, deficiencies are quite uncommon. However, people who do not get enough riboflavin can suffer from dry or cracked skin, especially around the lips or corners of the mouth. Other symptoms include skin rashes and eye irritation. Severe deficiencies may lead to depression or hysteria.

What can happen if I take too much?

Excess consumption of riboflavin may cause a person's urine to become bright yellow, but to date, no toxic side-effects have been reported. Because it is water-soluble and is not stored in the body, the chances of enough riboflavin building up to toxic levels are highly unlikely. Most people taking multivitamins with high levels of riboflavin or eating foods rich in riboflavin need not worry about toxicity.


  • B vitamins may cut heart disease risk. Harvard Health News April 1998.
  • B vitamins and the heart: what men can learn from women. Harvard Men's Health Watch June 1998.
  • Recommended Dietary Allowances, 10th ed. Washington, D.C.: National Academy Press, 1989.
  • Schoenen J; Jacquy J; Lenaerts M. Effectiveness of high-dose riboflavin in migraine prophylaxis. A randomized controlled trial. Neurology Feb 1998;50:466-470.
  • Ajayi OA, George B, Ipadeola T. Clinical trial of riboflavin in sickle cell disease. East Afr Med J Jul 1993;70(7):418-21.
  • Garrison R, Somer E. The Nutrition Desk Reference. New Canaan, CT: Keats Publishing, 1995.
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