TUESDAY, Nov. 1 (HealthDay News) -- Results of a small study show that obese men who take a small daily dose of the supplement resveratrol -- found as a natural compound in red wine -- appear to improve their metabolism as much as if they were on a strict low-calorie diet.

Animal studies have previously found that resveratrol reduces insulin resistance and protects against the bad effects of a high-fat diet. This is similar to what happens when people restrict the number of calories they take in, which has been shown to delay the onset of age-related diseases, the Dutch researchers say.

"Now we have shown for the first time that resveratrol works in humans. It opens the avenue for more research to see if it could be helpful in people with type 2 diabetes," said lead researcher Patrick Schrauwen from Maastricht University in the Netherlands.

"This is very positive news," he added. "We need further studies, but I would advise people to use resveratrol."

The study is published in the Nov. 2 issue of Cell Metabolism.

For the study, Schrauwen's team gave resveratrol to 11 obese, but otherwise healthy men. The men took 150 milligrams of the supplement a day for 30 days. To get that much resveratrol from wine would mean drinking over two gallons of wine a day, he noted.

The researchers found resveratrol acted much like a low-calorie diet in terms of reducing energy expenditure and improving metabolism and overall health.

Changes included a lower metabolic rate, reduced fat in the liver, lower blood pressure and lower blood sugar. The men also had changes in the way their muscles burned fat, the researchers found.

In obesity, it's not clear whether burning fewer calories is a good or a bad thing, Schrauwen noted. It suggests, however, that cells were functioning more efficiently, as they do on a calorie-restricted diet, he said.

There were no serious side effects seen among the men taking resveratrol, he added.

Resveratrol is widely available, but more work is needed to see if it has the potential to help obesity and delay aging, the researchers pointed out.

The study was funded by Top Institute Food and Nutrition, which Schrauwen described as a nonprofit consortium of universities and the food industry in the Netherlands.

Dr. David L. Katz, director of the Prevention Research Center at Yale University School of Medicine, said "resveratrol, an antioxidant compound concentrated in grape skin -- and thus red wine -- had previously been shown in animal studies to influence gene expression in a manner closely resembling that of calorie restriction."

This change of gene behavior is not just about weight loss or even metabolic improvements; calorie restriction has long been associated with extending lifespan, he said.

"No study long enough has ever been done in humans to show this pertains to us -- but all the signs suggest that it should," Katz said.

Now a human study showing that resveratrol mimics effects of calorie restriction in men as well as mice is "stunning," he said.

"Of course, we do not know what the long-term effects of resveratrol supplementation in humans will be. Perhaps effects wear off with time. Perhaps adverse aspects of altered gene expression show up late. We have leapt before without looking carefully enough, and should proceed with caution and care," Katz said.

"But for now, we have the first clear evidence that a natural compound can exert the same profound effects on metabolism, weight and genes in humans," he explained.

"There is at least reason to hope a meaningful anti-aging effect could be appreciated as well," Katz said. "I rarely get excited by any one research paper. I am excited about this one."

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