title: The effect of grape-skin extract on oxidative status.
abstract: Epidemiological studies indicate that moderate alcohol consumption, particularly wine, reduce the risk of CHD. The present study was designed to investigate the effect of grape-skin extract on markers of oxidative status. The study was designed as a randomised crossover. A diet with a low content of flavonoids was served with strict control of intake in two consecutive 1-week intervention periods to fifteen subjects (nine women, six men) divided randomly into two groups. During one of the weeks the subjects from either group consumed 200 ml grape-skin extract in water (1 mg extract/ml) at each of three daily meals (31.3 mg total phenolics, including 9.0 mg catechin). An increased activity of glutathione reductase and a borderline increase of glutathione peroxidase activity in erythrocytes were observed after grape-skin intervention, while the intervention had no significant effect on superoxide dismutase or catalase. Likewise, no effect was found on 2-aminoadipic semialdehyde (AAS) residues, a plasma protein oxidation product, or on malondialdehyde in plasma or in LDL, which are markers of lipoprotein oxidation. A marginal effect of grape-skin intervention was observed on plasma ascorbate levels. Intake of the experimental diet significantly reduced plasma vitamin C and plasma AAS in both groups. This effect was most pronounced in the particular week with no grape-skin extract addition. We speculate that grape-skin extract may have a sparing effect on vitamin C. The effects of the experimental diet may be partly ascribed to a low content of several fruit- and vegetable-related antioxidants like flavonoids and vitamin C and a relatively high content of carrot-derived antioxidants, such as carotenes.
authors: Research Department of Human Nutrition, Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
authors: J F
authors: JF
authors: Young
authors: L O
authors: LO
authors: Dragsted
authors: B
authors: B
authors: Daneshvar
authors: S T
authors: ST
authors: Lauridsen
authors: M
authors: M
authors: Hansen
authors: B
authors: B
authors: Sandström
mesh_terms: D015074:2-Aminoadipic Acid / Q000031:analogs & derivatives / Q000097:blood; D000328:Adult; D000704:Analysis of Variance; D000975:Antioxidants / Q000032:analysis*; D001205:Ascorbic Acid / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D002374:Catalase / Q000378:metabolism; D018592:Cross-Over Studies; D004912:Erythrocytes / Q000201:enzymology*; D005260:Female; D005419:Flavonoids / Q000008:administration & dosage*; D005979:Glutathione Peroxidase / Q000378:metabolism*; D005980:Glutathione Reductase / Q000378:metabolism*; D006801:Humans; D008077:Lipoproteins, LDL / Q000737:chemistry; D008297:Male; D008315:Malondialdehyde / Q000032:analysis / Q000097:blood; D010084:Oxidation-Reduction; D019685:Rosales / Q000737:chemistry*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D005419:Flavonoids; D008077:Lipoproteins, LDL; D015074:2-Aminoadipic Acid; C000061:allysine; D008315:Malondialdehyde; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D001205:Ascorbic Acid