ALCOHOL-FREE RED WINE ENHANCES PLASMA ANTIOXIDANT CAPACITY IN HUMANS

Moderate wine consumption is reputed to exert a protective effect agai nst coronary heart disease (CHD). The nature of the protective compoun ds is unclear and the mechanisms are incompletely understood. We studi ed whether the nonalcoholic component of wine increases plasma antioxi dant capacity measured as total radical-trapping antioxidant parameter (TRAP), and whether such an effect is associated with the presence of phenolic compounds in plasma. The TRAP and plasma levels of phenolic compounds were measured in 10 healthy subjects after the ingestion of 113 mL of tap water (control) and alcohol-free red and white wine at I -wk intervals. Both alcohol-free wines possessed an in vitro dose-depe ndent peroxyl-radical activity, but red wine, with a polyphenol concen tration of 363 +/- 48.0 mg/L quercetin equivalent (QE), was 20 times m ore active (40.0 +/- 0.1 mmol/L) than white wine (1.9 + 0.1 mmol/L), w hich has a polyphenol concentration of 31 +/- 1 mg QE/L. The ingestion of alcohol-free red wine caused significant increases in plasma TRAP values and polyphenol concentrations 50 min after ingestion. Alcohol-f ree white wine and water had no effects on either of the plasma values . The parallel and prompt increase of antioxidant status and of circul ating levels of polyphenols in fasting subjects after bolus ingestion of a moderate amount of alcohol-free red wine suggests that polyphenol s are absorbed in the upper gastrointestinal tract and might be direct ly involved in the in vivo antioxidant defenses.