Wednesday’s Ask Dr. Walt — Venomous Vitamins?

Dear Dr. Walt,

Being over 50 years old, my husband and I are looking to take a daily vitamin B-12 supplement. Many contain a type of B-12 called cyanocobalamin, yet I read on the Internet that this is actually toxic. Should I be concerned??

—We “Be” Interested in Tennessee

Dear Vitamin Buffs,

The scientific name for vitamin B-12 is cobalamin. The most common and least expensive B-12 supplement is the formulation you ask about called cyanocobalamin. Although this formulation does include a cyanide molecule, thus your question, experts uniformly consider it is very safe. Why? According to, “Even at a very high dose, it would provide about a thousand times less cyanide than is toxic, and the cyanide is quickly excreted in the urine.”

I should also point out that B-12 is also commonly available in supplements as methylcobalamin or hydroxycobalamin. ConsumerLab points out, “Some non-authoritative websites claim that methylcobalamin is better absorbed or more bioavailable than cyanocobalamin, but there is no clinical evidence supporting this claim.” Other sites suggest that methylcobalamin supplements cannot yield one of the important, active metabolites of B-12, but according to the experts I interviewed, this is not correct. There are also those who claim that B-12 nasal sprays, filmstrips, sublingual tablets, liquid drops, or even shots are better absorbed, albeit far more expensive than oral tablets. But every study I’ve seen has shown that taking inexpensive vitamin B-12 by mouth works as well as taking vitamin B-12 in any of these other forms.

Many physicians recommend that all of their patients over the age of fifty take 1-2 mg (1000-2000 mcg) of vitamin B12 per day as many people at this age are less able to extract B-12 from food. They also recommend B-12 for those taking medications that interfere with B-12 absorption, for strict vegans or vegetarians, and for people recovering from surgery or burns.

Although I recommend that, when possible, vitamins be obtained from a healthy diet, and not via supplements, this can be a problem for vegans or vegetarians as B-12 is naturally found in animal products, including fish, meat, poultry, eggs, milk, and milk products. However, vegans and vegetarians can use fortified breakfast cereals as they are a readily available source of vitamin B-12 with high bioavailability.

Dr. Walt

© Copyright WLL, INC. 2018. This blog provides a wide variety of general health information only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment from your regular physician. If you are concerned about your health, take what you learn from this blog and meet with your personal doctor to discuss your concerns.
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