The forms of vitamin B12 in foods.

1. The forms of vitamin B12 were determined in foods, most of which had been prepared for consumption. 2. Five forms were detected: adenosylcobalamin, hydroxocobalamin, methylcobalamin, cyanocobalamin and sulphitocobalamin. Adenoxylcobalamin and hydroxocobalamin were the predominant forms. 3. The intestinal absorption of [57Co]sulphitocobalamin was estimated and found to be lower than that of [58Co]cyanocobalamin.