The red wine ingredient resveratrol mimicked the metabolic effects of dieting and exercising in obese men, a small study found.
Although it didn't lead to weight loss, a daily 150-milligram dose of resveratrol lowered blood pressure as well as blood glucose levels and liver fat in obese men after 30 days, Dutch researchers reported today in the journal Cell Metabolism.
"It seems to make you metabolically healthier without weight loss," said study author Patrick Schrauwen of Maastricht University in the Netherlands. "I don't think it's a weight-loss drug."
Resveratrol -- a compound found in grape skin, peanuts and dark chocolate -- has made headlines in recent years for its reputed health benefits. In 2006, Harvard researchers reported its ability to counteract the harmful effects of a high-fat diet and lower the risk of death in mice. It has also been shown to reduce cancer risk and slow aging in laboratory models -- findings yet to be replicated in humans despite soaring sales of the supplement.
"It had been shown in animal and cell studies to have potent effects on metabolic health but there were no human studies," Schrauwen said. "Our study shows that resveratrol can indeed have beneficial metabolic effects in humans."
Obesity ups the risk of type 2 diabetes, a metabolic disease caused by insulin resistance. But after 30 days of resveratrol, study subjects showed signs of improved insulin sensitivity.
"The next steps are to see what the long-term effects are, but also to see if it might be even beneficial in people with type 2 diabetes who have a lot of metabolic disturbances," Schrauwen said.
Although the effects of resveratrol on metabolism were promising, they were small compared to the effects of exercise. Experts stressed that the supplement should be viewed as just that, a supplement to a healthy diet and active lifestyle.
"It would be a mistake to even hint that resveratrol could be a license to forego attempts at eating well and being active," said Dr. David Katz, director of the Yale University Prevention Research Center. "Eating well and being active can help prevent heart disease, cancer, stroke and diabetes. We have no evidence yet -- and might never have any -- that resveratrol can do these things. Even if resveratrol lives up to its early promise, it should be combined with best efforts at living well, not substituted for them."
But for obese people who struggle with exercise, resveratrol might offer a safety net of sorts.
"That's good news," said Keith Ayoob, director of the Rose R. Kennedy Center Nutrition Clinic at Albert Einstein College of Medicine in New York City, "but I'd be concerned that it might make people be more tolerant of their obesity, since they'd be able to mitigate some of the metabolic complications of being overweight."
Ayoob said people who are obese can build up their ability to exercise by sticking with it.
"There's no substitute for simply starting and being persistent," he said. "Resveratrol may be good for staving off some of the complications of obesity while people are on the way towards losing the weight."
Schrauwen said no side effects were seen throughout the study, but cautioned that more research is needed to understand the supplement's long-term effects.
The study also opens the door for the development of new, more potent drugs that target the same pathway as resveratrol.
"So many people suffer from these diseases," Schrauwen said of obesity and diabetes. "We're all looking for new targets. I think this is first study to show in humans that targeting this pathway can work."