A natural compound found in red wine may protect the heart against the effects of the aging process, researchers said on Tuesday.

In their study, mice were given a diet supplemented with the compound known as resveratrol starting at their equivalent of middle age until old age.

These mice experienced changes in their gene activity related to aging in a way very similar to mice that were placed on a so-called calorie restriction diet that slows the aging process by greatly cutting dietary energy intake.

Most striking was how the resveratrol, like calorie restriction, blocked the decline in heart function typically associated with aging, according to Tomas Prolla, a University of Wisconsin professor of genetics who helped lead the study.

Much as Spaniard Juan Ponce de Leon once searched for the mythical fountain of youth, researchers now are seeking ways to extend the quality and length of human life.

In some studies, animals given a diet with greatly reduced caloric intake have lived longer than animals with normal diets. But perpetual hunger is a steep price to pay for greater longevity, some researchers say.

Resveratrol, found in abundance in grapes and in red wine, has drawn a lot of interest from scientists and some companies, including GlaxoSmithKline, which in April said it would pay $720 million to buy Sirtris Pharmaceuticals Inc, a company that is developing drugs that mimic the effects of resveratrol.

Some studies have shown that in high doses, resveratrol extended the life span of fruit flies and worms and prevented early death in mice fed a high-fat diet.

In this study, mice were given relatively low doses compared to the earlier research, and still experienced important aging-related benefits, the researchers said.

The researchers began giving the resveratrol diet to the mice when they were 14 months old -- their middle age -- and followed the animals until they were about 30 months old. The researchers then conducted tests on cardiac function and on gene activity related to aging.

"Resveratrol at low doses can retard some aspects of the aging process, including heart aging, and it may do so by mimicking some of the effects of caloric restriction, which is known to retard aging in several tissues and extend life span," added Prolla, whose study was published in the scientific journal PLoS ONE.

Using a method that permits simultaneous analysis of thousands of genes at the same time, the researchers found a huge overlap in the genes whose activity were changed by resveratrol and caloric restriction.

They looked at the heart, brain and muscles, and said that the effect of resveratrol was strongest in the heart but did prevent some aging-related changes in the other tissues.

Just because mice had these benefits does not mean people also would, although Prolla said, "I think there's a high likelihood that our findings are applicable to humans."

He said he expected to see a lot of studies in the coming years on the effects of resveratrol supplementation in people.