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Ask any omnivore what they think the biggest problem with vegetarian and vegan diets is, and they'll point you to either iron or protein deficiencies. While vegetarians and vegans can indeed end up deficient in either, making sure you get enough iron and protein from non-meat sources really isn't that hard.
Not so with vitamin B12.
Vitamin B12 is present in almost all food products of animal origin, including meat from mammals, shellfish, fish and poultry. It's also found in dairy and eggs, which may offer some consolation to vegetarians, though nearly all B12 is gone after eggs have been heated — which almost always happens before you consume them. Vitamin B12 is also present in some algae (including the spirulina that's so popular among many vegetarians and vegans), but scientists have concluded the form found in algae is mainly "pseudovitamin", as opposed to biologically active B12. What's vitamin B12 not present in? Everything else you'd eat as a vegetarian, unless it was fortified.
Does this matter? You bet. Let's examine why.
Vitamin B12: The Basics
Vitamin B12 is a water-soluable vitamin, one of eight B vitamins. It's made by some types of bacteria, which can synthesize it. Note: because B12 is made by bacteria and bacteria are involved in the fermentation process, some people believe that fermented plant products, notably kimchi, contain B12. While we should mention that kimchi can contain fish and may be a source of vitamin B12 as such, the bacteria that make B12 aren't involved in the process of fermenting plant foods, and kimchi and similar foods should not be relied on as a source of B12. If you're veggie, you're probably making sure your kimchi doesn't have fish in any case.
Why do you need vitamin B12? It's actually involved in some pretty important stuff, including keeping your brain, nervous system, DNA, and metabolism working the way it should. Because a vitamin B12 deficiency can boost your levels of the amino acid homocysteine, an amino acid that's strongly correlated with increasing a person's risk of heart attack and stroke, a B12 deficiency puts you at risk.
I'll admit it: as a life-long vegeterian, a vitamin B12 deficiency had never been on my radar, until I saw my doctor about symptoms I really didn't want to have. Find out whether you have similar symptoms on the next page.