Cyanocobalamin is a cheap synthetic form of B12 that does release cyanide
when metabolized by our bodies.
The amount of cyanide is small and our bodies can detoxify it, but our bodies have to work to convert Cyanocobalamin to methylcobalamin, the active form. It is far better to take the methylcobalamin form. See http://www.Naturalnews.Com/027045_vitamin_b12_cyanocobalamin_methylcobalamin.Html.