title: Production of vitamin B 12 analogues in patients with small-bowel bacterial overgrowth.
abstract: We investigated the presence of vitamin B 12 analogues (cobamides) and the bacterial conversion of 57Co-B12 (vitamin B12 cyanocobalamin, [57Co]-CN-Cbl) into cobamides in the intestinal contents of four patients with bacterial overgrowth. The (57Co)-CN-Cbl bound to intrinsic factor was given orally. Jejunal contents were aspirated for 24 h and cultured aerobically and anaerobically. The CN-Cbl and cobamides were separated by electrophoresis and chromatography and identified by bioautography. Radioactivity of cobamide zones from duplicate chromatograms showed bacterial conversion of (57Co)-cn-cbl into cobamides. Cobamides ([Ade]CNCBA, [2-Me Ade] CNCba, [CN]2Cbi and factor E) were found in the intestinal contents in three of the four patients, and in two of three patients cobamides represented more than 25% of the administered CN-Cbl. Thus bacterial production of cobamides, both de novo and from ingested CN-Cbl bound to intrinsic factor, occurs in humans with bacterial overgrowth states and results in a significant loss of vitamin B12 to the host.
mesh_terms: D000749:Anemia, Megaloblastic / Q000382:microbiology; D001419:Bacteria / Q000378:metabolism; D003038:Cobamides / Q000032:analysis* / Q000096:biosynthesis; D004238:Diverticulitis / Q000378:metabolism; D006801:Humans; D007415:Intestinal Obstruction / Q000378:metabolism; D007421:Intestine, Small / Q000032:analysis / Q000378:metabolism* / Q000382:microbiology; D008286:Malabsorption Syndromes / Q000209:etiology / Q000378:metabolism*; D014805:Vitamin B 12 / Q000378:metabolism*
chemical_list: D003038:Cobamides; D014805:Vitamin B 12