title: The bioavailability of alpha- and beta-carotene is affected by gut microflora in the rat.
abstract: The present study examined whether the intestinal microflora could affect the bioavailability and vitamin A activity of dietary alpha- and beta-carotene in the rat. In the first set of experiments, we used conventional, germ-free (axenic), and human-flora-associated (heteroxenic) rats. In a second series, conventional rats were treated with either an antibiotic mixture or a potent inhibitor of gastric secretion (Omeprazole). All animals were first depleted of vitamin A over 4 weeks and then were fed on a sterilized diet supplemented with 14 mg beta-carotene and 3 mg alpha-carotene/kg for 2 weeks. In both experiments, a reduction in the intestinal microflora resulted in an increased storage of beta-carotene, alpha-carotene and vitamin A in the liver. Neither the nature of the metabolism of the intestinal microflora (aerobic or anaerobic) nor treatment with omeprazole, to modify intestinal pH, induced a significant effect on the measured variables. When incubated with 15 mumol beta-carotene/l for 72 h, neither the anaerobic nor the aerobic sub-fractions obtained from rat or human faeces contributed to beta-carotene degradation or to vitamin A synthesis. These findings suggest that reduction in gut microflora results in a better utilization of alpha- and beta-carotene by rats, although bacteria do not have a direct effect on the bioavailability of these pigments.
authors.affiliation: Centre de Recherche en Nutrition Humaine de Clermont-Ferrand, Unité des Maladies Métaboliques et Micronutriments, INRA, Saint-Genès-Champanelle, France. inravita@nut.fr
authors.forename: P
authors.initials: P
authors.lastname: Grolier
authors.forename: P
authors.initials: P
authors.lastname: Borel
authors.forename: C
authors.initials: C
authors.lastname: Duszka
authors.forename: S
authors.initials: S
authors.lastname: Lory
authors.forename: M C
authors.initials: MC
authors.lastname: Alexandre-Gouabau
authors.forename: V
authors.initials: V
authors.lastname: Azais-Braesco
authors.forename: L
authors.initials: L
authors.lastname: Nugon-Baudon
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D001682:Biological Availability; D002338:Carotenoids / Q000493:pharmacokinetics*; D004791:Enzyme Inhibitors / Q000008:administration & dosage; D005243:Feces / Q000382:microbiology; D005260:Female; D005856:Germ-Free Life; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000382:microbiology*; D008099:Liver / Q000378:metabolism*; D009853:Omeprazole / Q000008:administration & dosage; D051381:Rats; D011916:Rats, Inbred F344; D017208:Rats, Wistar; D014801:Vitamin A / Q000378:metabolism*; D019207:beta Carotene / Q000493:pharmacokinetics
chemical_list: D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D019207:beta Carotene; D014801:Vitamin A; D002338:Carotenoids; C041635:alpha-carotene; D009853:Omeprazole