Wine is already known to confer considerable social benefits, and in recent years scientists have begun to explore its potential health benefits as well. But can a pill really replicate the beneficial effects of the occasional glass of pinot noir?

Resveratrol, a compound found in grape skins, is the target of many studies seeking to find the key to wine’s health-boosting properties. It’s already touted for a wide range of supposedly protective properties – guarding against cancer, elongating lifespan and lowering blood sugar. Most of these claims are based on preliminary animal research, but people are buying it -- literally. In recent years, sales of resveratrol supplements have rung up more than $30 million per year, according to the Nutrition Business Journal.

But for healthy folks looking to stave off diabetes, is there any benefit to taking resveratrol supplements? One new study is dashing cold water on that idea.

In a paper published Thursday in the journal Cell Metabolism, a team led by Washington University St. Louis School of Medicine researcher Samuel Klein looked at the effects of resveratrol supplements in 29 reasonably healthy post-menopausal women. Half of the group took 75 milligrams of resveratrol per day for 12 weeks, while the other half took placebo pills.

What effect did the researchers find? The short answer is none.

“Our study really shows that dose of resveratrol we used does not have any beneficial metabolic effects in healthy women,” Klein said in a phone interview.

To measure the subjects’ sensitivity to insulin and their glucose uptake, the researchers used a procedure that involves infusing different doses of insulin into a subject’s body and seeing how they react. It’s the most precise, reproducible method for measuring insulin sensitivity in people that’s available, according to Klein.

Klein says his team’s study is the first to explore the insulin sensitivity effects of resveratrol in healthy adults. Other work has been done in humans, but in specific unhealthy groups: obese men or people with type 2 diabetes, for example.

Plus, in three human studies suggesting resveratrol confers metabolic benefits, two of those did not use a control group, Klein points out.

In animal studies that found more impressive effects of resveratrol, researchers typically use much higher doses of the compound. Also, they will often inject animals rather than administer resveratrol orally, which could affect how the compound is absorbed, according to Klein.

But there are plenty of studies showing that people who drink red wine are less likely to have heart disease and diabetes. It may be that resveratrol isn’t the magic bullet, though.

"We were unable to detect a metabolic benefit of resveratrol supplementation in our study population, but this does not preclude the possibility that resveratrol could have a synergistic effect when combined with other compounds in red wine," Klein said in a statement Thursday.

SOURCE: Yoshino et al. “Resveratrol Supplementation Does Not Improve Metabolic Function in Nonobese Women with Normal Glucose Tolerance.” Cell Metabolism published online 25 October 2012.

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