In a Harvard Medical School & National Institute of Aging study, they tested 3 groups of mice. One was fed a standard diet, one a high-calorie, high-fat diet, & one a high-calorie, high-fat diet WITH Resveratrol. After 6 months the diet that included Resveratrol prevented most of the negative side effects of the high calorie diet. It also protected the mice against heart disease, diabetes & other illnesses normally associated with a diet of red meat, cheese & pastries.
However, don't down that bottle of meriot just yet. The average bottle of red wine has 2-4 milligrams of resveratrol, but the studies used doses of 250-1000mg. Plus, not all wine is equally potent. If the grapes are chemically treated with pesticides, as most are, they don't produce as much resveratrolas they don't need to protect themselves from the bugs. The study recommends taking a supplement with 250-500mg of organic resveratrol a day, although some studies have shown that up to 1000mg might be better.