Intake of a resveratrol-containing dietary supplement has no impact on DNA stability in healthy subjects

It has been postulated that the beneficial health effects of dietary supplements and of red wines which contain resveratrol (RES) are due to the anti-oxidative properties of this phenolic compound, but evidence for protection against reactive oxygen species is mainly based on results of in vitro experiments and high-dose animal experiments. Aim of this study was to find out if intake of a RES-containing supplement protects healthy humans against oxidative DNA-damage and alters their redox status. Therefore, an intervention trial was conducted in which the participants (n=12) consumed a RES-containing supplement over a period of five days. At the start, after one day and after five days of consumption, and after a washout period DNA stability was measured in single cell gel electrophoresis (SCGE) assays with peripheral blood lymphocytes. These tests were conducted (a) under standard conditions, which reflect single- and double-strand DNA breaks, (b) after treatment of the cells with hydrogen peroxide, which enables detection of alterations of the ROS sensitivity, and (c) by use of formamidopyrimidine DNA-glycosylase (FPG), which provides information on formation of oxidatively damaged bases (pyrimidines). Furthermore, the biochemical parameters TAC (total antioxidant capacity) and oxLDL (oxidized low-density lipoprotein), which reflect the redox status, and C-reactive protein (CRP), a marker of inflammation, were monitored. The intake of the supplement had no significant impact on the DNA stability parameters and on the different biomarkers of the redox status. Our results indicate that intake of 6mg RES per day via the supplement does not cause DNA-protective or antioxidant effects. This amount is equivalent to or lower than that reached after intake of many (ca. 50%) of the RES-containing preparations which are currently on the market in Middle Europe, and is contained in 0.3-2L red wine.