FAQs on vitamin B12: everything you wanted--and need--to know about this B vitamin.(SUPPLEMENT: ESSENTIAL)(Drug overview)

Ever wonder why vitamin B12 is called cobalamin? It's because it contains the metal cobalt. While that factoid may surprise you, vitamin B12's importance in maintaining a healthy nervous system is well known. B12 plays a vital role in red and white blood cell maintenance, as well as brain, spinal cord, nerve, skin and internal organ functioning.

What Are Food Sources of B12?

Animal products (meat, fish, eggs, dairy) are the best sources--oysters, sardines, tuna, eggs and cottage cheese are particularly high in B12. Fortified cereal is another good source.

How Much Do I Need?

The RDA for adults is just 2.4mcg. Dosages vary considerably in products sold--ranging from the RDA to 5,000mcg. Since the body stores several years' worth of vitamin B12, you may not need to take a daily dose, says Amy Joy Lanou, PhD, assistant professor of nutrition at the University of North Carolina, Asheville. But, she adds, vegans and people who adhere to a strict macrobiotic diet may require either fortified foods or supplements.

Might I Be Deficient?

One of the most common reasons for a B12 deficiency is a lack of intrinsic factor, a compound that allows the body to properly absorb vitamin B12. Pernicious anemia sufferers lack this substance and therefore often need high doses of B12. Stomach or intestinal disorders, such as celiac or inflammatory bowel disease, can prevent vitamin B12 from being absorbed, as can surgery involving removal of part of the stomach or intestine (including gastric bypass surgery). People with eating disorders are also at a ...