Aging mice fed a chemical found in red wine were healthier in their twilight years, scientists have confirmed, although the rodents didn't necessarily live longer.

The anti-aging effects of the compound, resveratrol, mimic those of a calorie-restricted diet, which has been shown to give mice, dogs, and worms longer, healthier lives. Although resveratrol only extended the lives of obese mice in this latest study, it made all the animals healthier. They were spared the worst of some of the declines that come with old age, and they had healthier cardiovascular systems and stronger bones than did untreated animals. Non-obese mice fed resveratrol also had significantly lower total cholesterol. The study was done by the National Institute on Aging, as a follow-up to 2006 findings that resveratrol improves the health and longevity of overweight, aged mice.

The study offers yet more evidence of the possible anti-aging benefits of resveratrol. "Is this too good to be true?" asks Harvard Medical School's David Sinclair, one of the authors of the paper, which appears this week in Cell Metabolism. "I think we'll know in the next few years." Sinclair initially showed the anti-aging effect of resveratrol several years ago. Sirtris Pharmaceuticals, the company that he cofounded to develop anti-aging drugs, including ones based on resveratrol, was recently sold to GlaxoSmithKline for about $720 million.

Sinclair and his colleagues gave one-year-old mice--that's middle-aged, in mouse years-- high doses of resveratrol. It's found in the skins of grapes--which are left on the fruit when red wine is fermented but removed from white wine before fermentation--and in lower amounts in peanuts and some berries, including cranberries and blueberries.

Resveratrol had a broad range of health benefits for mice, the researchers confirmed. The mice had fewer cataracts, better bone density, healthier cardiovascular systems, and better motor coordination than did untreated animals, and resveratrol also made obese mice more sensitive to insulin.

"Let's hope it will do the same things for humans," says Mark Leid, a professor in the Department of Pharmaceutical Sciences at Oregon State University. He wasn't involved in this work.

Other studies have found that resveratrol extends life span in various organisms, including fish, flies, and yeast, and in mice fed a high-calorie diet. This study found the same effect in obese mice, although they still didn't live as long as mice on a normal diet. Resveratrol had no effect on the life span of animals fed a normal diet, although they had a healthier old age.