Look at your multivitamin… if you see the ingredient, “cyanocobalamin,” then your supplement comes with an extra special component of cyanide… a substance poisonous in larger amounts. Must we now say “sayonara” to cyano-cobalamin?
With all things considered, the answer is: probably not. Cobalamin (vitamin B12) bound to cyanide (cyanocobalamin) is one of the most stable (non-perishable) and cheapest forms of this vitamin, making it the most common form of B12 on the market. Vitamin B12 is important because it helps the brain and nerves function. It is especially imperative vegans and vegetarians ensure adequate levels of B12, as animal products are the main source, including meat, milk, eggs, and fish— and there are no naturally-occurring vegetable dietary sources of this vitamin. B12 deficiency can cause severe and irreversible damage to the brain and nervous system. When levels of B12 are even slightly lower than normal, symptoms such as fatigue, lethargy, depression, poor memory, and headaches may be experienced, especially in people over age 60. Very low levels can cause mania and psychosis.
Cyanocobalamin is better than no cobalamin at all, if there is a risk of deficiency. The body detoxifies the small amount of cyanide that it removes from cobalamin before the vitamin can perform its biologically indispensable roles within the body. However, cyanide in its non-vitamin form, is an extremely toxic poison. It only takes 6.44 mg per kilogram, or 1.61 mg to kill an average-sized (500 gram) rat through the oral route of exposure. The margin of safety (as defined by the LD50) for cyanocobalamin, on the other hand, is approximately 1,000 times higher. In vitamins, therefore, the amount of cyanide is about 1,000 times less cyanide than would be a toxic amount, and whatever is absorbed is excreted in urine.
However, those with a higher body burden or higher cyanide exposure, such as smokers, will have extra levels of cyanide to detoxify, and may want to consider avoiding the seemingly benign levels found in some vitamins and foods.
In all, despite its ubiquitous form, cyanocobalamin is not the most health-conscious formulation out there. Methylcobalamin, while more expensive, and hydroxocobalamin are arguably more ideal forms of this vitamin.
An entirely different approach to maintaining adequate vitamin B12 levels is through supporting the microflora in the gut, as these beneficial bacteria are proficient in producing this indispensable vitamin. Probiotics with Lactobacillus reuteri, for instance, have been studied for their vitamin B12-producing properties.
Other dietary sources of biologically-active B12 include spirulina, chlorella, and white button mushrooms.
It should also be noted that proton pump inhibitors (drugs that block acid production to treat reflux) prevent vitamin B12 absorption and microwaving food deactivates this vitamin, as well.
Finally, while you go to check your labels, make sure your supplements do not contain sugar substitutes to make them taste better. Mannitol, sorbitol, and/or sucralose can cause gas, bloating, and even diarrhea, in some people.
So while you should not “B”-afraid of B12 supplement, just know that there are other, less potentially risky, sources out there.