Comparative Absorption of Vitamin B12 Analogues by Normal Humans. I. Chlorocobalamin vs. Cyanocobalamin

Abstract

1. Urinary excretion tests performed with cobalt-60 labeled cobalamins by the method of Schilling indicate that the absorption of chlorocobalamin at the 2 μg dose level by the normal young adult male is much less than that of cyanocobalamin at the same oral level. 2. Normal chlorocobalamin and cyanocobalamin appear to be equivalent in their capacity for liberating absorbed labeled cobalamins by injection of massive doses. 3. Differences in the ease of absorption of the cobalamins are attributed to differences in their electrolyte nature and attendant solubility properties.