There are many things to worry about in life, but cyanide in vitamin B12 supplements is not one of them. Why do I mention this? Because of a video that has been circulating about “the toxic ingredient in your child’s vitamins.” In the video, a man talks about how he finds it “hard to believe we’re allowed to make vitamins with hydrogen cyanide in this country, but we are.” That man turns out to be Gary Brecka, who labels himself a “human biologist,” whatever that means, on the basis of having a bachelor’s degree in Human Biology from the National College of Chiropractic. Not exactly Harvard.
Yes, there is actually cyanide in B12 supplements, but the scare is total nonsense. Vitamin B12 is synthesized by bacteria that inhabit the intestines of animals and is present in foods of animal origin. These bacteria are not found in fruits, grains, or vegetables, so vegetarians and vegans are generally advised to take a supplement. Vitamin B12, which is needed by the body for various tasks ranging from red blood cell production and DNA synthesis to proper nerve function, is actually not a single compound. The term can refer to any of four very closely related compounds, each of which has vitamin activity. They share the common feature of having a cobalt atom in the center of the molecule, but they differ in the substituents attached to that atom. This has nothing to do with its biological activity.
None of these “vitamers,” as they are called, can be synthesized from simple molecules in the laboratory, so the supplements must be produced by fermentation using the same bacteria that produce B12 in animals. Fermentation produces adenosylcobalamin and methylcobalamin, but the problem here is that they tend to break down when formulated into supplements. However, treatment with potassium cyanide (not hydrogen cyanide as indicated in the video) converts them to cyanocobalamin, which is very stable. Once ingested, cyanocobalamin converts back to the original adenosylcobalamin and methylcobalamin, releasing the cyanide in the process. This is where the scare originates.
Doses of vitamin B12 are measured in micrograms, that is, in millionths of a gram. The recommended daily intake is 2 to 3 micrograms, but supplements can contain up to a couple of thousand because vitamin B12 is not well absorbed from the intestine. Even at the highest doses, the amount of cyanide released is about 20 to 40 micrograms, which is much less than the amount of natural cyanide one might be exposed to by consuming raw flaxseed, almond milk, juice of fresh apple or apricots.
The oral dose of cyanide below which there is no risk has been determined to be 50 micrograms per kg of body weight. This means that a child weighing 15kg given a whopping daily dose of 1000 micrograms of B12 would still be taking in less than 3% of this safe amount! There is simply no problem here. What about people who are drawn to smoothies made from raw almonds or flaxseed, which contain the highest doses of cyanide one could reasonably be exposed to? A 70kg adult would have to consume 16 regular sized shakes in less than two hours to get cyanide poisoning! A child would have to drink around three. This, of course, is totally unreal. But what about someone who drinks a shake every day that contains as much cyanide as a shake can contain, which is about 220 micrograms per serving? Still less than 6% of the maximum safe dose!
Bottom line? There is no reason to worry about cyanide in vitamin B12 supplements, but there is reason to worry about self-appointed pseudo-experts with an incomplete understanding of the science alarming the public, usually with an eye to financial gain in some way.
