Are Intestinal Bacteria a Reliable Source of B12?
Summary: Given that many otherwise healthy vegans develop B12 deficiency when not supplementing their diets with B12, intestinal bacteria cannot be relied upon to prevent B12 deficiency in vegans. Are raw foodists or people who eat fermented foods exceptions? No. See the section B12 Status: Raw Foodist Vegans. Bacteria in the Large Intestine It has long been assumed that B12 is produced by bacteria in the large intestine (aka the colon), but since B12 is produced below the ileum (where B12 is absorbed), it is not available for absorption. This theory is reinforced by the fact that many species of totally or primarily vegetarian animals eat their feces. It is surmised that eating feces allows them to obtain B12 on their diets of plant foods. Although I believe this to be true, it has not been verified beyond a reasonable doubt. The best evidence I have found for this theory is reported by Herbert.1 He reports a study in the 1950s in England where vegan volunteers with B12 deficiency (as
