FAQs on vitamin B12: everything you wanted—and need—to know about this B vitamin

Better Nutrition, Oct, 2006 by Maryann Hammers

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 higher risk of deficiency. Antacids and ulcer medications can inhibit absorption. And with aging, levels often decline.

What If I Take More than I Need?

"No adverse effects have been associated with excess vitamin B12 intake from food and supplements in healthy individuals," says The Institute of Medicine of the National Academy of Sciences.

What Are Some Possible Uses?

Some research has shown that vitamin B12, particularly when combined with other B vitamins, may he helpful for maintaining proper homocysteine levels. Scientists have noted that Alzheimer's patients tend to have elevated levels of homocysteine along with low levels of folate and vitamin B12. Recently, research has indicated that osteoporosis is also linked to high homocysteine and low B12 levels.

What Forms Are Available?

You can take a multivitamin, a B complex or B 12 individually. "I like chewable or sublingual versions because some absorption happens through the mouth," says Lanou.

JARROW FORMULAS METHYL B-12 5000mcg is a sugar-free lozenge designed to dissolve under the tongue.

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SOLARAY VITAMIN B-12 2000mcg contains 90 lozenges naturally flavored with cherry and sorbitol.

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SUPERIOR SOURCE NO SHOT B-12 1,000mcg is a micro-tablet that instantly dissolves under the tongue.

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TWINLAB B-12 DOTS have 500mg of vitamin B12 and are suitable for vegetarians.

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