title: Neomycin has no persistent sparing effect on vitamin B-12 status in pectin-fed rats.
abstract: In the present study, rats were depleted of vitamin B-12 with fiber-free or 5% pectin diets, with or without neomycin. Through use of this intestinal antibiotic reported to "spare" vitamin B-12, we sought to determine if bacterial fermentation of pectin might explain our previous observations of negative effects of pectin on vitamin B-12 status. However, neomycin did not lessen interference by pectin with vitamin B-12 metabolism. Pectin increased urinary methylmalonate and decreased propionate oxidation to a greater extent in the presence than in the absence of neomycin. Also, regardless of the presence of neomycin, the biologic half-life of injected [57Co]vitamin B-12 was 58 d for rats fed the fiber-free diets and only 38 d for rats fed 5% pectin diets. Neomycin delayed early fecal excretion of 57Co but had no persistent effect. Thus, neomycin-sensitive bacteria do not mediate the negative effects of pectin on vitamin B-12 status. Pectin may interfere directly with vitamin B-12 absorption or may stimulate vitamin B-12 uptake or propionate production by microbial species that have adapted to neomycin.
authors.affiliation: Department of Nutritional Sciences, University of California, Berkeley 94720.
authors.forename: R W
authors.initials: RW
authors.lastname: Cullen
authors.forename: S M
authors.initials: SM
authors.lastname: Oace
mesh_terms: D000818:Animals; D004032:Diet; D004043:Dietary Fiber / Q000378:metabolism; D005285:Fermentation / Q000187:drug effects; D007408:Intestinal Absorption / Q000187:drug effects; D007422:Intestines / Q000382:microbiology*; D008297:Male; D008764:Methylmalonic Acid / Q000378:metabolism; D009355:Neomycin / Q000494:pharmacology*; D009752:Nutritional Status; D010084:Oxidation-Reduction / Q000187:drug effects; D010368:Pectins / Q000008:administration & dosage*; D051381:Rats; D011916:Rats, Inbred F344; D014805:Vitamin B 12 / Q000378:metabolism*; D014806:Vitamin B 12 Deficiency / Q000378:metabolism
chemical_list: D004043:Dietary Fiber; D010368:Pectins; D008764:Methylmalonic Acid; D009355:Neomycin; D014805:Vitamin B 12