Unlike most other vitamins, vitamin B12 is not made by plants or animals. Rather, it is made from bacteria. Thus, the argument that vegans can make their own B12 from intestinal bacteria seemingly makes sense. Some nutritionists like Dr. Charles Partito make compelling arguments about the existence of B12 in plants. Of course, the guy is trying to sell you his cleansing products though. The same goes for Dr. Vivian Vetrano who says that B12 coenzymes are readily found in raw plants. She’d like you to join her retreat.
But all unbiased health experts have come to pretty much the same conclusion about whether vegans can get B12 from intestinal bacteria: they can’t.
Dietician Jack Norris points out some compelling studies about B12 and intestinal bacteria. For starters, he notes that B12 is produced in the large intestine, which is located below the ileum where it is absorbed. Thus, the B12 which is made naturally in the body cannot be absorbed.
Vegans could get B12 by consuming their own fecal matter though and studies have shown that eating poop can provide B12. You’d have to be a pretty extreme vegan to eat your own crap just to get B12 – especially when fortified foods and supplements are so readily available.
Norris goes on to mention studies which found that Indian immigrants had higher levels of B12 in their intestines than Westerners. Some vegans have used these studies to argue that B12 supplementation is unnecessary. However, the reason for the higher B12 levels could be attributed to contamination of food/water by fecal matter – something common in developing countries.
So, how is it that vegetarian animals like cows and sheep can make their own B12 but humans cannot? One reason is because many vegetarian animals (like cows and sheep) have stomachs with four chambers. The first chamber, called the rumen, is rich in bacteria which can make B12. Other animals also have stomachs which are shaped differently and allow more bacterial fermentation.
Another reason that vegetarian animals aren’t B12 deficient is that they often consume soil along with their food. Soil often contains cobalt, which is necessary for making B12 in the intestines. As Dr. Justine Butler points out, many primates have been known to eat dirt to naturally treat/combat nutrient deficiencies. When moved to a zoo and fed a sterile diet, many primates develop B12 deficiencies.
Of course, there are plenty of health experts who have opposing opinions saying that you can get B12 from intestinal bacteria. This is usually contingent upon eating unwashed foods which were grown organically in manure compost. So, unless you are prepared to eat dirt (or poop), then you will need to take a B12 supplement as a vegan.