Myths and Facts about Vitamin B-12
by Valerie Copeland, TVS

Most of us know that vegetarians live longer, and have less cancer, heart disease, and risk of stroke. Vegetarian (including vegan) meals supply adequate amounts of all the nutrients that we need - with the possible exception of Vitamin B-12, which is important for making red blood cells and maintaining the nervous system.

Vitamin B-12 is an essential vitamin that is only produced by microorganisms such as bacteria, fungi and algae; animals and plants cannot synthesize B-12 (animals are B-12 sources to non-vegetarians because animals ingest microorganisms). Unwashed vegetables may also contain significant sources if they are contaminated with B-12 containing bacteria. However, in developed countries where vegetables are washed during harvest, these bacteria are easily lost.

Vitamin B-12 requirements are small. The Recommended Daily Allowance is 2 micrograms (mcg), and experts believe that 1 mcg/day may be sufficient 1. Deficiency is rare, since our bodies typically store several years' worth of B-12, conserving it by reabsorbing it from our waste. By far the most common B-12 problem isn't lack in the diet, but inability for a small number of people to absorb it due to enzymatic deficiencies; these people may receive periodic B-12 injections. You should see your doctor if you feel that you may have a B-12 deficiency.

Requirements are small, deficiency is rare ... Sources include enriched cereals, fortified soymilk, supplements, and fortified nutritional yeast

Lacto-ovo vegetarians who eat a variety of foods have no problem meeting all of their vitamin needs, including B-12. Lacto-vegetarians also have little difficulty getting B-12 in their diet. However, vegans may be deficient in B-12 if they are not making a conscious effort to include a regular, reliable source of B-12 in their diet.

Many foods once popularly thought to contain B-12 do not in fact contain it, or contain only analogs that resemble B-12 but have no biological activity and actually inhibit B-12 absorption. The following either contain no B-12 or contain B-12 analogs 2:

Foods with no B-12 or that inhibit B-12
TempehAmaranthTamari
ShoyuSpinachMiso
AlfalfaTurnip greens Umeboshi plums
AlgaeLegumesTofu
SpirulinaPeanutsBarley malt syrup
ComfreySoybeansSourdough bread
Rainwater Shiitake mushrooms
Sea vegetables (arame, wasake, kombu)

Reliable sources of B-12 can easily be found in many enriched breakfast cereals, fortified soymilk (such as Eden Soy Extra), some meat analogues, and all common multivitamin supplement tablets (look for it by its chemical name of {it}cyanocobalamin{/it}). Fortified nutritional yeast is also an excellent source, such as Red Star T6635 (one tablespoon provides 4 mcg). These products can be readily found in local whole foods stores, such as Harmony Farms, Wellspring Grocery, and Weaver Street Market.


1 Herbert, V. (1988) "Vitamin B{sub}12{/sub}: Plant Sources, Requirements, and Assay." {it}Am J Clin Nutr{/it} 1988, 48:852-858.

2 Messina, M. and Messina, V. (1996) in {it}The Dietitian's Guide to Vegetarian Diets, Issues and Applications{/it}. Aspen Publishers, Inc., Gaithersburg, MD, page 168.