Vitamin B12, also known as cobalamin due to the presence of the mineral cobalt, is a vital water-soluble vitamin necessary for numerous bodily functions. There are several forms of vitamin B12, each with slightly different chemical structures, including cyanocobalamin (CNCbl), hydroxocobalamin, methylcobalamin (MeCbl), and adenosylcobalamin (AdoCbl). When selecting a vitamin B12 supplement, you’ll find that these products can contain any one of these forms.