Resveratrol may turn out to be the Energizer battery of the wine world. Not only does the compound found in grape skins help mice live longer, it also increases their endurance and limits weight gain, according to a new study published online this week in Cell.
"One of the ways to extend life is to increase the production of energy," said study author Johan Auwerx, head of research at the Institute of Genetics and Molecular and Cellular Biology in Illkirch, France. "And resveratrol does just that."
Just two weeks ago, a study done at Harvard Medical School found that resveratrol can counteract the effects of an unhealthy diet in rodents. "Resveratrol has recently been found to prolong the life of mice, possibly by reducing obesity and maybe even diet-related diseases, such as diabetes," explained Auwerx. Like his U.S. colleagues, he was studying whether the polyphenol could offset the effects of a high-fat diet, particularly metabolic syndrome, a precursor to type 2 diabetes.
When mice in his study were given resveratrol, they did not develop metabolic syndrome, and they gained less weight and developed muscles similar to those of trained athletes, despite eating a high-calorie diet. Auwerx said that resveratrol may be extending life "by boosting health overall, and it looks promising that it will do the same in men."
However, he cautioned that a human would have to drink "hundreds of glasses of red wine to reach the same levels of resveratrol" that the mice were fed in his study. "But, it is possible that you may get a cumulative dose effect that is beneficial after drinking two or three glasses a night for many years."
Resveratrol's reputation as a life-extender comes not only from the recent study in mice, but from previous studies showing it increases longevity foryeast, fruit flies and earthworms and tropical killifish. The compound may help prevent heart disease and diabetes, contribute to lower cholesterol levels, alleviate some lung ailments, fight certain types of cancer and reduce the growth of skin melanomas.
Auwerx's team hypothesized that if resveratrol extends life by keeping organisms healthier, then those creatures would also be in better physical shape overall. To test that, they examined the endurance of mice in laboratory trials.
The researchers fed one group of mice a standard chow diet and fed a second group a high-fat, high-calorie diet. In each group, half the mice were also given resveratrol--in amounts of 400 milligrams per kilogram of body weight--with their daily meals for 15 weeks.
Auwerx's team found that mice ran twice as long on treadmills when their diets were supplemented with resveratrol. Mice without the resveratrol refused to continue running after, on average, 1 kilometer. The mice on resveratrol, by contrast, kept going for between 1.75 and 2 kilometers.
Mice on the high-fat diet could run for a kilometer at a time but gained 60 percent of their original body weight in just nine weeks. By comparison, mice on a high-fat diet supplemented with resveratrol put on only 25 percent of their original weight. The scientists also observed that the resveratrol-fed mice were able to better regulate their insulin and glucose levels.
Lab tests on the dissected mice indicated that resveratrol acted metabolically to provide added endurance, Auwerx said. After mapping out the genetic activity, he theorized that resveratrol activates sirtuins, enzymes that protect DNA from damage and regulate aging--a finding also made in the Harvard study. These enzymes in turn activate a receptor gene, PGC-1a, which makes muscles more resistant to fatigue and cold and is credited with the ability to create more mitochondria, organelles that act as power stations for the body's cells.
Auwerx found higher numbers of mitochondria in the muscle cells of the resveratrol-fed mice, which would have helped them generate more energy and burn more fat. Resveratrol actually "reprograms muscle," said the study, to operate more efficiently. And the mice fed resveratrol displayed more of the muscle type found in marathon runners, but "not the type used for a burst of energy, like in sprinters," Auwerx said.
Resveratrol did not appear to have any toxic effects on the mice, the authors wrote, nor did it change behavior.
Resveratrol supplements have reportedly been flying off the shelves since the publication of the Harvard Medical School study on longevity in mice. However, Auwerx believes that pill poppers will most likely not live any longer or run any farther than red wine drinkers.
"I don't encourage resveratrol supplements, as you never know what's in there," he said, "and, typically, resveratrol available from stores is not pure." He added, "It's best to get it from natural sources."
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