Vitamin B12 for vegans

March 31, 11:28 AMSeattle Vegan ExaminerVirginia Messina, MPH, RD

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Vegan diets take a lot of flack in the news media for all kinds of reasons, but the alleged “B12 problem” is probably one of the biggest. I talked yesterday about why the B12 issue doesn’t make much of an argument against vegan diets. We evolved to get by on just a smidgeon of this vitamin, and it’s very easy to get enough.

But, yes—vegans do need to give a little bit of thought about where they will get B12.

All of the vitamin B12 in the world is made by bacteria and this has given rise to a host of myths about sources of this vitamin. Soyfoods like tempeh and miso should be good sources of B12 since they utilize microbes for fermentation, but in most cases, they are not. Likewise, brewer’s yeast, nutritional yeast, sour dough bread, shiitake mushrooms, and sea vegetables are not reliable sources for vegans unless they are fortified. And many of these foods contain B12 analogs which can interfere with vitamin activity, increasing the risk of deficiency.

Since humans store big stashes of B12 in their liver, new vegans can stay healthy for a long time—even several years—without B12 in their diet. This can create a false sense of security—and lots of false information about B12.  There is no way of knowing just how much B12 you have to spare, so vegans should always include a good source in their diet.

A shortage of B12 leads to anemia and sometimes even neurological symptoms that can’t be reversed. But even marginal B12 deficiency—which can go undetected for years—can take its toll since it can lead to elevated levels of a compound called homocysteine, which raises risk for heart disease and other conditions.

So—smart vegans supplement their diets with B12. Two servings a day of a fortified food—including many brands of soymilk, some meat analogs, and some breakfast cereals—can meet B12 needs. In the United States, one brand of nutritional yeast is reliably fortified –Red Star brand Vegetarian Support Formula. In other countries, yeast products like Vegemite may be fortified, but that’s not always true. Be sure to read the label. No type of yeast is a good source of B12 if it isn’t fortified.

If you prefer not to think about it too much, just use a supplement. Choose one that is chewable since this greatly improves B12 absorption. Take a daily tablet providing between 10 and 100 micrograms of B12 or a weekly supplement that offers around 2,000 micrograms. It’s simple and smart.