A compound found in trace amounts in grape skins, peanuts, and red wine may defend against harmful changes seen in obesity that often precede diseases like type 2 diabetes, a small new study shows.
These changes include inflammation in the body and insulin insensitivity.
The study is one of the first to test the compound, called resveratrol, in humans. It is published in the journal Cell Metabolism.
In previous studies, resveratrol has been shown to extend the lives of obese mice. It also has been shown to increase endurance, helping rodents run about twice as far on a treadmill before they collapse from exhaustion.
Researchers wanted to know if humans who took resveratrol would see similar benefits.
To find out, they gave 11 obese men who had no family history of diabetes or other endocrine diseases a daily dose of resveratrol or a placebo pill for 30 days.
The dose of resveratrol used in the study, 150 milligrams, was far lower than an equivalent dose tested in mice, but it was still hefty. To get the equivalent from red wine, researchers say a person would have to drink more than 13 bottles a day.
All the men took both the resveratrol and the placebo, though the pills were disguised and given four weeks apart, so the men didn't know when they were on each regimen.
"We saw a lot of effects on metabolism that all point toward better metabolic health," says study researcher Patrick Schrauwen, PhD, professor in the metabolic aspects of type 2 diabetes at Maastricht University in the Netherlands.
"For example, blood glucose levels go down, insulin levels go down, triglyceride levels go down, but also fat in the liver goes down," Schrauwen says.
Activity in mitochondria, the energy factories inside cells, increased. Resveratrol also appeared to change how muscles burned fat, and it lowered some indicators of inflammation.
"Those are also things that you see with exercise training or calorie restriction," Schrauwen says.
But unlike exercise or cutting calories, resveratrol didn't help the men lose weight. In fact, it actually slowed metabolism. Schrauwen says a slower metabolism may be a sign that the body is using energy more efficiently.
"I don't think it will be a drug that will help you to lose weight," he says. "But it may help you to become metabolically more healthy."
Time to Take Resveratrol?
Several pharmaceutical companies are testing molecules that activate the same chemical pathways as resveratrol, hoping to find drugs that may extend life and defend against conditions like type 2 diabetes, heart disease, and dementia.
Experts who were not involved in the research called the findings exciting, but urged caution.
"This is quite impressive in terms of getting some data on clinical trials in humans," says Philippe Marambaud, PhD, Alzheimer's scientist at the Feinstein Institute for Medical Research in Manhasset, N.Y.
"It's a small group, and it's a short-term study," he says. "The long-term effects could be 10 times better or they could wash out."
"The study is absolutely important. This is a fantastic extension to humans of what we knew in the mice," says Rafael de Cabo, PhD, a senior investigator at the National Institute on Aging, in Bethesda, Md.
But de Cabo says there's more to learn before people should take it. "There's a lot more work to do before we can recommend to anyone to take resveratrol."
There were no significant side effects reported in this study, but de Cabo says that could change when the supplement is taken by more people for longer periods of time.
"One of the things that still needs to be addressed is if resveratrol is safe in combination with other medications," de Cabo says.