title: Lipid peroxidation and coupled vitamin oxidation in simulated and human gastric fluid inhibited by dietary polyphenols: health implications.
abstract: The Western diet contains large quantities of oxidized lipids, because a large proportion of the food in the diet is consumed in a fried, heated, processed, or stored form. We investigated the reaction that could occur in the acidic pH of the stomach and accelerate the generation of lipid hydroperoxides and cooxidation of dietary vitamins. To estimate the oxygen content in the stomach after food consumption, oxygen released from masticated bread (20 g) into deoxygenated water (100 mL) was measured. Under these conditions, the oxygen concentration rose by 250 microM and reached a full oxygen saturation. The present study demonstrated that heated red meat homogenized in human gastric fluid, at pH 3.0, generated hydroperoxides and malondialdehyde. The cross-reaction between free radicals produced during this reaction cooxidized vitamin E, beta-carotene, and vitamin C. Both lipid peroxidation and cooxidation of vitamin E and beta-carotene were inhibited at pH 3.0 by red wine polyphenols. Ascorbic acid (44 mg) at a concentration that represented the amount that could be ingested during a meal inhibited lipid peroxidation only slightly. Red wine polyphenols failed to prevent ascorbic acid oxidation significantly but, in conjunction with ascorbic acid, did inhibit lipid peroxidation. In the presence of catechin, a well-known polyphenol found in red wine, ascorbic acid at pH 3.0 works in a synergistic manner preventing lipid peroxidation and beta-carotene cooxidation. The present data may explain the major benefits to our health and the crucial role of consuming food products rich in dietary antioxidants such as fruits, vegetables, red wines, or green tea during the meal.
authors.affiliation: Department of Food Science, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
authors.forename: Shlomit
authors.initials: S
authors.lastname: Gorelik
authors.forename: Tair
authors.initials: T
authors.lastname: Lapidot
authors.forename: Inbal
authors.initials: I
authors.lastname: Shaham
authors.forename: Rina
authors.initials: R
authors.lastname: Granit
authors.forename: Moshe
authors.initials: M
authors.lastname: Ligumsky
authors.forename: Ron
authors.initials: R
authors.lastname: Kohen
authors.forename: Joseph
authors.initials: J
authors.lastname: Kanner
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage; D002392:Catechin / Q000494:pharmacology; D004032:Diet; D005419:Flavonoids / Q000494:pharmacology*; D005750:Gastric Juice / Q000737:chemistry*; D006293:Health Promotion; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015227:Lipid Peroxidation / Q000187:drug effects*; D008460:Meat / Q000032:analysis; D008954:Models, Biological; D010084:Oxidation-Reduction; D010636:Phenols / Q000494:pharmacology*; D059808:Polyphenols; D013024:Soybean Oil / Q000737:chemistry; D014815:Vitamins / Q000737:chemistry*; D014920:Wine / Q000032:analysis; D019207:beta Carotene / Q000737:chemistry
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D014815:Vitamins; D019207:beta Carotene; D013024:Soybean Oil; D002392:Catechin