Comparison of the antioxidant effects of Concord grape juice flavonoids α-tocopherol on markers of oxidative stress in healthy adults

• Published in: The American journal of clinical nutrition Vol. 76; no. 6; pp. 1367 - 1374
• Main Authors: O'Byrne, Dawn J, Devaraj, Sridevi, Grundy, Scott M, Jialal, ishwarlal
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Clinical Nutrition 01.12.2002; American Society for Clinical Nutrition, Inc
• Subjects: Adult; Adults; alpha-tocopherol; alpha-Tocopherol - blood; alpha-Tocopherol - pharmacology; Antioxidants; Antioxidants - pharmacology; Ascorbic Acid - blood; Beverages; Beverages - analysis; Biological and medical sciences; blood proteins; Blood Proteins - analysis; chronic diseases; Comparative analysis; Dietary Supplements; Effects; F2-Isoprostanes - urine; Feeding. Feeding behavior; flavonoids; Flavonoids - pharmacology; Free Radical Scavengers; Fundamental and applied biological sciences. Psychology; grape juice; Health; Humans; Lipid Peroxidation - drug effects; Lipoproteins, LDL - blood; low density lipoprotein; oxidation; Oxidation-Reduction; oxidative stress; Oxidative Stress - drug effects; oxygen radical absorbance capacity; phenols; Reactive Oxygen Species - blood; risk; Stress; triacylglycerols; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vitis - chemistry; Human; Oxidative stress; oxygen radical absorbance capacity; Vitamin; LDL oxidation; urinary F2-isoprostanes; Biological marker; α-Tocopherol; Supplemented diet; Antioxidant; Flavonoid; Fruit juice; grape juice; Biological activity; Feeding; protein carbonyls; Grape; Adult; flavonoids
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/76.6.1367

Background: Concord grape juice (CGJ) is a rich source of flavonoids, which have greater antioxidant efficacy in vitro than does alpha-tocopherol; however, the efficacies of flavonoids and alpha-tocopherol in vivo have not been compared. Objective: We compared the in vivo antioxidant efficacy of CGJ with that of alpha-tocopherol in healthy adults. Design: Subjects were randomly assigned to receive either 400 IU RRR-alpha-tocopherol/d (n = 17) or 10 mL CGJ · kg-1 · d-1 (n = 15) for 2 wk. Serum oxygen radical absorbance capacity, plasma protein carbonyls, urinary F2-isoprostanes, and resistance of LDL to ex vivo oxidation were measured before and after supplementation as markers of antioxidant status and oxidative stress. Results: After supplementation, plasma α-tocopherol increased 92% in subjects who received α-tocopherol (P < 0.001); plasma total and conjugated phenols increased 17% (P < 0.01) and 22% (P < 0.001), respectively, in subjects who received CGJ. There was a significant change in plasma triacylglycerols in both groups, but the concentrations were within the normal range. CGJ supplementation was associated with significantly higher triacylglycerols than was alpha-tocopherol supplementation. Both supplementation regimens significantly increased serum oxygen radical absorbance capacity (P < 0.001) and LDL lag time (P < 0.001) and significantly decreased the LDL oxidation rate (P < 0.01), with no significant difference in effectiveness. Protein carbonyl concentrations in native plasma decreased 20% after CGJ supplementation, which was a significantly different response than that after α-tocopherol supplementation (P < 0.05). Conclusions: In healthy adults, 10 mL CGJ · kg-1 · d-1 increased serum antioxidant capacity and protected LDL against oxidation to an extent similar to that obtained with 400 IU α-tocopherol/d but decreased native plasma protein oxidation significantly more than did alpha-tocopherol. CGJ flavonoids are potent antioxidants that may protect against oxidative stress and reduce the risk of free radical damage and chronic diseases.