Why vegans who eat no animal products should take a vitamin B 12 supplement?

Re: Why vegans who eat no animal products should take a vitamin B 12 supplement?

The following information is from:

http://www.bastyrcenter.org/content/view/235/

True vegans who eat no animal products at all generally require vitamin B 12 supplementation, as it is only found in animal foods.

In the past, popular literature suggested that miso, tempeh, tamari, sea vegetables and some greens were adequate vitamin B 12 sources due to either their fermentation status, or to healthy contamination with vitamin B 12 producing bacteria.

However, research has shown that these foods do not consistently provide vitamin B 12, and that even if the vitamin is present, it is generally in an analogue form not easily used by the body.

Therefore, all vegans should proactively consume foods fortified with vitamin B 12 as indicated on the food label. Fortified products include breakfast cereals, fortified meat substitute products and fortified soy and grain milks.

If such foods are not eaten with regularity, vegans should take a vitamin B 12 supplement to ensure they receive this essential nutrient.