Written on 08 March 2013.

Vitamin B12

Frequently Asked Questions (FAQ)
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What about vitamin B12 on a vegan diet?

The data on B12 is still coming in, so it is impossible to say "It's no problem....", however, the latest information suggests that acquiring enough B12 is not as problematic as it was once thought. If you are concerned about inadequate B12, there are many foods which are fortified with B12, in addition to vitamin pills - these vary in different countries, so check the labels and local info sources.

Here is further information: From the book: Simply Vegan: Quick Vegetarian Meals, by Debra Wasserman and Nutrition Section by Reed Mangels, Ph.D., R.D. Published (1990/1991) by the Vegetarian Resource Group, P.O. Box 1463, Baltimore, MD 21203, (410) 366-VEGE. ISBN 0-931411-05-X

Summary: The requirement for vitamin B12 is very low. It is especially important for pregnant and lactating women, infants, and children to have reliable sources of vitamin B12 in their diets.

Vitamin B12 is needed for cell division and blood formation. Plant foods do not contain vitamin B12 except when they are contaminated by microorganisms. Thus, vegans need to look to other sources to get vitamin B12 in their diet. Although the minimum requirement for vitamin B12 is quite small, 1/1000 of a milligram (1 microgram) a day for adults, a vitamin B12 deficiency is a very serious problem leading ultimately to irreversible nerve damage. Prudent vegans will include sources of vitamin B12 in their diets.

Bacteria in the human intestinal tract do make vitamin B12. However, the majority of these bacteria are found in the large intestine. Vitamin B12 does not appear to be absorbed from the large intestine.

Normally, vitamin B12 is secreted into the small intestine along with bile and other secretions and is reabsorbed, but this does not add to the body's vitamin B12 stores. Since small amounts of vitamin B12 are not reabsorbed, it is possible that eventually vitamin B12 stores will be used up.

At this time, research is continuing on vitamin B12 requirements. Some researchers have even hypothesized that vegans are more efficient than the general public in absorbing vitamin B12. Certainly for other nutrients, such as iron, absorption is highest on low dietary intakes. However, these are only speculations. We need to look for reliable dietary sources for vitamin B12 until we can determine whether or not other sources can supply adequate vitamin B12.

Although some vegans may get vitamin B12 from inadequate hand washing, this is not a reliable vitamin B12 source. Vegans who previously ate animal-based foods may have vitamin B12 stores that will not be depleted for 20 to 30 years or more. However, long-term vegans, infants, children, and pregnant and lactating women (due to increased needs) should be especially careful to get enough vitamin B12.

Few reliable vegan food sources for vitamin B12 are known. Tempeh, miso, and seaweed often are labeled as having large amounts of vitamin B12. However, these products are not reliable sources of the vitamin because the amount of vitamin B12 present depends on the type of processing the food undergoes. Also, Victor Herbert, a leading authority on vitamin B12 states that the amount on the label cannot be trusted because the current method for measuring vitamin B12 in foods measures both active and inactive forms of vitamin B12. The inactive form (also called analogues) actually interferes with normal vitamin B12 absorption and metabolism. These foods may contain more inactive than active vitamin B12.

The RDA (which includes a safety factor) for adults for vitamin B12 is 2 micrograms daily. Of course, since vitamin B12 is stored, you could use larger amounts of nutritional yeast less often.

We recommend checking the label of your favorite foods since manufacturers have been known to stop including vitamin B12. Added vitamin B12 should be listed under ingredients and you can write to the company inquiring about the amount of vitamin B12 in a serving.

Other sources of vitamin B12 are fortified soy milk (check the label as this varies in different countries), vitamin B12 fortified meat analogues (some food made from wheat gluten or soybeans to resemble meat, poultry or fish - varies with different brands), and vitamin B12 supplements. There are vitamin supplements which do not contain animal products.

Further information on Vitamin B12