Vitamin B12 can be obtained from plant sources.
Of all the myths, this is perhaps the most dangerous. Vegans who do not supplement their diet with vitamin B12 will eventually get anaemia (a fatal condition) as well as severe nervous and digestive system damage (6). Claims are made that B12 is present in certain algae, tempeh (a fermented soy product) and brewer's yeast. All of them are false.
Like the niacin in corn, the B12 analogues present in algae and tempeh are not bioavailable. We know this because studies done on people's blood levels of B12 remained the same after they ate spirulina and tempeh; there was no change, clearly indicating no absorption by the body (7). Further, the ingestion of too much soy increases the body's need for B12 (8). Brewer's yeast does not contain B12 naturally; it is always fortified from an outside source.
Some vegetarian authorities claim that B12 is produced by certain fermenting bacteria in the intestines. This may be true, but it is in a form unusable by the body. B12 requires intrinsic factor from the stomach for proper absorption in the ileum. Since the bacterial product does not have intrinsic factor bound to it, it cannot be absorbed (9).
It is true that vegans living in certain parts of India do not suffer from vitamin B12 deficiency. This has led some to conclude that plant foods do provide this vitamin. This conclusion, however, is erroneous as many small insects, their eggs, larvae and/or residue, are left on the plant foods these people consume, due to non-use of pesticides and inefficient cleaning methods. This is how these people obtain their vitamin B12. This contention is borne out by the fact that when Indian Hindus migrated to England, they came down with pernicious anaemia within a few years. In England, the food supply is cleaner, and insect residues are completely removed from plant foods (10).
The only reliable and absorbable sources of vitamin B12 are animal products, especially organ meats and eggs (11). Though present in lesser amounts, milk products do contain B12. Vegans, therefore, should consider adding dairy products into their diets. If dairy cannot be tolerated, eggs, preferably from free-run hens, are a virtual necessity.
That vitamin B12 can only be obtained from animal products is one of the strongest arguments against veganism being a "normal" way of human eating. Today, vegans can avoid anaemia by taking supplemental vitamins or fortified foods. If those same people had lived just a few decades ago, when these products were unavailable, they would have died.
In my own practice, I recently saved two vegans from death from anaemia by convincing them to eat generous amounts of dairy products. Both of these sickly gentlemen thought their B12 needs were being met by tempeh and spirulina. They weren't.
- Written by Randy Voyard
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