Consumption of red wine polyphenols reduces the susceptibility of low-density lipoproteins to oxidation in vivo.

Red wine polyphenols (RWPPs) were obtained from red wine by absorption and elution from a resin column. Red wine (375 mL/d), white wine (375 mL/d), RWPPs (1 g/d, equivalent to 375 mL red wine/d) in capsules, RWPPs (1 g/d) dissolved in white wine, or a control alcoholic drink (40 g ethanol/d) was given to groups of 6-9 healthy men for 2 wk. Plasma LDL was separated by ultracentrifugation and desalted by dialyzing against a phosphate buffer without EDTA. In the copper-catalyzed peroxidation of LDL (copper-diene assay), the mean lag time increased by 17.8 min after red wine, 14.2 min after RWPP capsules, and 11.7 min after RWPPs in white wine. These groups also showed decreases in thiobarbituric acid-reactive substances, lipid peroxides, and conjugated dienes and increases in plasma and LDL polyphenols. The only change with white wine was an increase in thiobarbituric acid-reactive substances; there were no changes after the control drink. In a second study, RWPPs (1 and 2 g/d) and vitamin E [1000 IU (671 mg)/d] were given for 2 wk. In the copper-diene assay the addition of 10 micromol EDTA/L abolished the increased lag time of 17.7 min seen with 1 g RWPP/d and changed the increased lag time from 13.2 to 4.5 min seen with 2 g RWPP/d. Vitamin E increased lag time by 67.6 min with dialysis without EDTA and by 50.5 min with EDTA. When the column method was used for desalting LDL, all 3 treatments produced an increase in lag time. The failure of some authors to obtain antioxidant effects with the consumption of red wine may be due to the differing techniques.