An Italian study has found that older adults with the highest concentration of resveratrol metabolites were no less likely to have died of any cause than those with no resveratrol found in their urine. The concentration of resveratrol was not associated with inflammatory markers, cardiovascular disease, or cancer rates. The finding indicates that whatever health benefits red wine, blueberries and dark chocolate have, it is not due to this antioxidant.
Given that the participants were from Tuscany, where consumption of red wine is the norm, I do wonder if the same result would have been found if people with very low consumption of resveratrol had been included. Perhaps there are no benefits over a certain level, but this is not to say there are no benefits for those below that level. But this is mere speculation on my part.