metabolic product of bacterial fermentation 3) extracted from sewage sludge.
Although generally accepted as safe (GRAS) by the FDA for human consumption, human studies
have reported allergic reactions to skin testing, and mice given 1.5-3 mg/kg body weight
experienced convulsions, followed by cardiac and respiratory failure.
Cyanocobalamin is not the active form of B12. In order for the body to use this form of B12 it must
enzymatically remove the cyanide portion of this molecule, releasing it in the form of thiocyanate
which can be safely excreted. The remaining cobalamin portion must then be converted into
methylcobalamin or adenosylcobalamin, in order for it to perform useful biological work. Because
some people lack the proper enzyme to actively detoxify and convert cyanocobalamin, or are
overwhelmed by the ingestion of too much cyanide, it can accumulate in the body resulting in
toxicity. (reference: Linnell JC, Matthews DM. Cobalamin metabolism and its clinical aspects. Clin Sci
(Lond). 1984 Feb/66(2):113-21.)