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

Am J Clin Nutr. 2002 Dec;76(6):1367-74. 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 F(2)-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 alpha-tocopherol increased 92% in subjects who received alpha-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 alpha-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 alpha-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.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Antioxidants / pharmacology*
  • Ascorbic Acid / blood
  • Beverages / analysis*
  • Blood Proteins / analysis
  • Dietary Supplements
  • F2-Isoprostanes / urine
  • Flavonoids / pharmacology*
  • Free Radical Scavengers
  • Humans
  • Lipid Peroxidation / drug effects
  • Lipoproteins, LDL / blood
  • Oxidation-Reduction
  • Oxidative Stress / drug effects*
  • Reactive Oxygen Species / blood
  • Vitis / chemistry*
  • alpha-Tocopherol / blood
  • alpha-Tocopherol / pharmacology*


  • Antioxidants
  • Blood Proteins
  • F2-Isoprostanes
  • Flavonoids
  • Free Radical Scavengers
  • Lipoproteins, LDL
  • Reactive Oxygen Species
  • alpha-Tocopherol
  • Ascorbic Acid