Data in this node is out of date. While is is highly debatable how much B12 is needed to remain healthy, it is clear that the amount varies highly from person to person, and that some tests traditionally used for measuring B12 do not accurately measure the B12 accessible for use by our bodies. It is becoming widely recognized that the current recommended daily allowance is too low.

IANAD, but it is safe to recommend a minimum daily intake of 10 micrograms a day. Vegans, vegetarians, and partial-vegetarians should take a supplement; while your body does store some B12, this stored B12 is not available for all necessary functions, and small but measurable ill-effects become apparent within a few months of beginning a reduce meat and/or dairy diet.

Please be aware that the majority of information you see on the internet is well out of date, and is often incorrect. Unfortunately, this is also true of the information given by many doctors.

It is important to remember that you body cannot use all types of B12. B12 from plant sources are highly unreliable, and it is probable that your body cannot use the B12 analogs that are often advertised from soy products and other vegetable sources; it is much more likely that these will inhibit your uptake of the forms of B12 that your body needs.

-- Tem42

For many vegans, vitamin B12 is the issue. More controversy exists over this nutrient than any other. The short story is this: Vegans need to supplement their diet with vitamin B12 or risk deficiency. There is really very little disagreement about this among health professionals with expertise in vegan diets. Even so, questions and misinformation about vitamin B12 continue to make the rounds among vegans.

All vitamin B12 comes from bacteria. These bacteria live in the soil and in the intestines of animals. The B12 they produce gets incorporated into animal tissue and animal products such has milk and eggs. Thus, animal products become a source of B12 for humans. Bacteria on the outside of plant foods also produce B12 and theoretically, when these foods are consumed, they can provide humans with B12. Realistically, normal cleaning of food eliminates most of the available B12; consequently, these foods are not a reliable source.

Some vegans are loathe to believe that they need supplements or fortified foods to meet B12 needs. In some cases, this might reflect a desire to believe that vegan diets are natural and sufficient without supplementation. Historically, vegan diets probably were completely adequate, and there is reason to believe that humans were perfectly suited to do without nonvegan food sources of B12. The requirement for vitamin B12 is infinitesimal - only 2 micrograms a day. In fact, one teaspoon of vitamin B12 would meet the needs of nearly one hundred people for the rest of their lives! In addition, our bodies hoard B12 by storing any excess and by recycling what is used. The fact that it is saved, combined with the minimal amount required, suggests that we evolved to live healthfully in a B12-poor environment. Without animal foods in the diet, we probably did just fine on the little bits of B12 we picked up here and there through contamination of food and water. In many parts of the world, this is still probably sufficient to meet B12 needs. Potential problems exist for Western vegans, however, because our food supplies are well sanitized, and contamination with B12-producing bacteria is less likely. Of course, there are many advantages to eating clean food, so any inconvenience over B12 is a small price to pay.

As a practical source of B12 for vegans today, fortified foods or supplements are probably the only answer. However, the quantity needed has been drastically overstated in many places. As Trevor Goodchild says above, only a very small amount is required by our bodies. However, this amount is not so small that we can blithely ignore it and count on increasingly unlikely happenstance to give us enough B12.

If you are vegan and pregnant, definitely make sure you're getting enough B12. Pregnancy places increased demands on your body for nutrition, and vitamin deficiencies during pregnancy have terrifying possible effects on your child. In the case of a B12 deficiency, rare though it is, the result may be a type of anaemia - treatable, but why subject yourself or your child to it? It is very possible to stay vegan while pregnant and breastfeeding, but care is required. Consult a doctor or nutritionist who has experience with vegan nutrition, and talk to vegans you know who have been pregnant while vegan.

If you are a lifelong or almost lifelong vegan, or if you have been vegan for more than 10 years, definitely make sure you're getting enough B12. If you ever ate meat for more than 10 years in your life, your body will have enough B12 to last you up to another 20 years or so after you cut out animal products, but don't wait too long before getting in to the habit of getting B12 in your diet.

But the good news: it's really really really easy to get B12. Just eat fortified nutritional yeast. Red Star brand is widely available in health stores, and contains B12 cultivated from vegan sources. Spirulina powder is another good source, although the way it turns anything you add it to bright green can be offputting. It's good in smoothies, and a teaspoon more than meets the RDA for B12. You can also try vitamin supplements, but be careful: many vitamin capsules contain gelatin, and even among those with vegan-friendly capsules, the B12 may have been produced with non-vegan methods. It all depends on how strictly vegan you are, but do some research. If you ask me, though, just skip the supplements and eat nutritional yeast. It's delicious, it has 1001 uses in vegan cooking, and it only takes a little bit to satisfy your B12 needs.

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