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Vitamin B12 and your healthWhen someone mentions "red vitamin", it is in reference to vitamin B12, whose crystalline form is colored red to pinkish. Another unique property of vitamin B12 is that it is the only vitamin built around an essential mineral - cobalt (hence the chemical names of its various forms: cyanocobalamin, methylcobalamin, etc.).
Your body needs B12 to form protective layer around nerves, for red blood cells production, metabolism of fats, carbohydrates and proteins, immune system function as well as for basic cellular functions, including formation of DNA and RNA. Vitamin B12 is also needed for the conversion of folate (natural form of vitamin B9) in its active form; it is an important cofactor needed for reduction of toxic homocysteine to methionine.
One more peculiar thing about vitamin B12 is that it can only be found in foods of animal origin. That puts vegetarians, and especially vegans, at the increased risk of developing deficiency. But the carnivores are not quite out of the woods either. Absorption of vitamin B12 requires presence of a
special enzyme called "intrinsic factor",
which in turn requires adequate stomach acid, with the acid pH not exceeding 2.0. Thus insufficient acid levels, as well as any form of malabsorption, will compromise effective body supply of vitamin B12.
In addition, it is not uncommon that the "intrinsic factor" is disabled by autoimmune reactions, or even not made at all. Moreover, a defective molecule transporting B12 to the tissues may result in deficiency even if the B12 serum reading is normal (granted, "normal" serum anything means little with respect to its actual body level).
The good news is that vitamin B12 is more stable than most other B-complex vitamins (only about 30% is lost in cooking). Also, it is stored in the liver which, combined with very small amounts of it needed daily by the body, can secure continued supply for years, independently of any additional intake. The only problem is that no one can tell how much of B12 - if any - you have stored in your liver.
Possible early signs of B12 deficiency, like dementia, poor attention span, or depression, often are not indicative enough of the specific cause. By the time one develops anemia, potentially irreversible nerve damage has already taken place. Considering this, it is very advisable to make sure your B12 levels are adequate. In supplementation, methylcobalamin is better absorbed and retained than other B12 forms.
However, risk of deficiency doesn't warrant excessive "just in case" intake. While B12 toxicity symptoms are often considered unlikely, they are possible and potentially serious. Long list of adverse effects that may be caused by B12 excess include anxiety, insomnia, numbness and tingling on the right side of the body (face or arm), damage to liver or kidneys, and others.
Vitamin B12 DRI (Dietary Reference Intakes, the most recent set of dietary recommendations set by the government) for an average healthy adult (female or male) is 0.024mg (2.4mcg). In pregnancy and lactation it is increased to 0.026mg and 0.028mg, respectively.
Best natural food sources of vitamin B12 are animal proteins, in particular liver, milk and dairy products.