Lowering of oxidative stress improves endothelial function in healthy subjects with habitually low intake of fruit and vegetables: a randomized controlled trial of antioxidant- and polyphenol-rich blackcurrant juice

Free Radic Biol Med. 2014 Jul:72:232-7. doi: 10.1016/j.freeradbiomed.2014.04.006. Epub 2014 Apr 15.


Inadequate intake of the recommended five-a-day fruit and vegetable portions might contribute to increased cardiovascular disease risk. We assessed the effects of dietary intake of a blackcurrant juice drink, rich in vitamin C and polyphenols, on oxidative stress and vascular function. This was a double-blind, placebo-controlled, parallel group study of 66 healthy adults who habitually consume <2 portions of fruit and vegetables per day. Participants were randomly allocated to consume 250ml of placebo (flavored water) or low or high blackcurrant juice drink four times a day for 6 weeks. Flow-mediated dilation (FMD) and plasma concentrations of F2-isoprostanes and vitamin C were measured. In the high blackcurrant juice drink group FMD increased significantly (5.8±3.1 to 6.9±3.1%, P=0.022) compared with the placebo group (6.0±2.2 to 5.1±2.4%). Plasma vitamin C concentration increased significantly in the low (38.6±17.6 to 49.4±21.0µmol/L, P<0.001) and high (34.6±20.4 to 73.8±23.3µmol/L, P<0.001) blackcurrant juice drink groups compared with the placebo group (38.1±21.0 to 29.0±17.6µmol/L). F2-isoprostane concentrations were significantly lower in the high blackcurrant juice drink group (225±64pg/ml) compared with the low blackcurrant juice drink (257±69pg/ml, P=0.002) and placebo group (254±59pg/ml, P=0.003). At follow-up, changes in plasma vitamin C correlated significantly with changes in FMD (r=0.308, P=0.044). Consumption of blackcurrant juice drink high in vitamin C and polyphenols can decrease oxidative stress and improve vascular health in individuals with habitually low dietary fruit and vegetable intake.

Keywords: Antioxidant; Blackcurrant juice; Endothelial function; Free radicals; Oxidative stress; Vitamin C.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antioxidants / pharmacology*
  • Ascorbic Acid / blood
  • Beverages*
  • Diet Therapy / methods*
  • Double-Blind Method
  • Endothelium, Vascular / drug effects*
  • Endothelium, Vascular / physiology
  • Female
  • Humans
  • Isoprostanes / blood
  • Male
  • Middle Aged
  • Oxidative Stress / drug effects*
  • Polyphenols / pharmacology
  • Ribes*
  • Vasodilation / drug effects
  • Vasodilation / physiology


  • Antioxidants
  • Isoprostanes
  • Polyphenols
  • Ascorbic Acid