Safety of Cyanide in Cyanocobalamin
Due to some articles going around the Internet, many people have written me asking whether vitamin B12 supplements in the form of cyanocobalamin are safe due to the cyanide content. Because so many people have asked, I have updated the page Side Effects of B12 Supplements of Vitamin B12: Are You Getting It? with the following information:
The safety of cyanocobalamin has raised concerns due to the fact that cyanide is a component of cyanocobalamin, and the cyanide molecule is removed from cyanocobalamin when used by the body’s cells. Cyanide is also found in many fruits and vegetables and so humans are always ingesting small amounts of cyanide, and like in most fruits and vegetables, the amount of cyanide in cyanocobalamin is considered to be physiologically insignificant.
According to the European Food Safety Authority, “Data of from a Norwegian dietary survey show that the average and high (97.5th percentile) daily intake of [cyanide] among consumers amounts to respectively 95 and 372 micrograms/person or 1.4 and 5.4 micrograms/kg bw/day (7).” The amount of cyanide in a 1,000 microgram cyanocobalamin is 20 micrograms.
Table 1 contains some additional numbers regarding cyanide amounts in cyanocobalamin for comparison purposes.
|Table 1. Cyanide Content of Cyanocobalamin|
|molecular weight of vitamin B12||1,355 g/mol|
|molecular weight of cyanide||27 g/mol|
|Percentage of cyanide in vitamin B12 by weight||2.0%|
|Amount of cyanide in 1,000 micrograms of cyanocobalamin||20 micrograms|
|Minimal Risk Level for oral cyanide4, a||0.05 mg/kg of body weight per day|
|Minimal Risk Level for oral cyanide for 140 lb person||3,175 micrograms/day|
|Percentage of Minimal Risk Level in 1,000 micrograms of cyanocobalamin||0.6%|
|Lethal dose of cyanide5||0.5 to 3.0 mg/kg of body weight|
|Lower end of lethal dose of cyanide for 140 lb person||31,750 micrograms|
|Percentage of lethal dose in 1,000 micrograms of cyanocobalamin||0.06%|
|aMinimal Risk Level do not assess cancer risk (6).|
In summary, the amount of cyanide in 1,000 micrograms of cyanocobalamin is about .6% of the amount that is thought to be the lower level that causes harm.
Thank you, Ginny, for sending some of the research!