Nonalcoholic red wine extract and quercetin inhibit LDL oxidation without affecting plasma antioxidant vitamin and carotenoid concentrations

Background: Antioxidant enrichment of LDL can increase its resistance to oxidation and hence reduce its atherogenicity. The objective of the present study was to investigate whether in vivo supplementation with nonalcoholic red wine extract and quercetin can increase the oxidative resistance of LDL, and also whether the supplementation has any effect on other antioxidative micronutrients present in the blood. Methods: Twenty-one male subjects were supplemented with a placebo drink for 2 weeks and randomized into two groups. One group (n = 11) received the red wine extract (1 g/day, equivalent to 375 mL of red wine) and the other group (n = 10) quercetin (30 mg/day) for 2 weeks, followed by a 5-week washout period. Results: In the red wine extract-supplemented group, ex vivo copper-initiated oxidation of LDL (lag phase, mean ± SD) was 40 ± 11 min at the baseline, and increased significantly to 47 ± 6 min [P