Identification and quantitation of cobalamin and cobalamin analogues in human feces.

摘要

BACKGROUND: Cobalamin (vitamin B-12) and cobalamin analogues are present in human feces, but a complete identification has not been established, and the amounts present have not been determined. OBJECTIVES: We aimed to develop a liquid chromatography-mass spectrometry method for cobalamin and cobalamin analogues and to identify and quantitiate the amounts present in human feces. DESIGN: Fecal samples were obtained from 20 human subjects in good general health. The samples were analyzed for the presence and amounts of cobalamin and 12 cobalamin analogues that were synthesized with and without the incorporation of stable isotopes. RESULTS: Cobalamin and 7 cobalamin analogues were identified and quantitated in human feces. The mean for the total amount present in 18 subjects whose daily intake was 98 of the total of cobalamin plus cobalamin analogues. A major portion of large amounts of ingested cobalamin appears to be converted to cobalamin analogues.