Oct. 25, 2012 -- New research raises doubts about the health benefits of the much-hyped red wine compound resveratrol.
In a study from Washington University School of Medicine in St. Louis, healthy women in their late 50s and early 60s who took resveratrol supplements showed no improvement in factors linked to developing diabetes and heart disease.
The finding suggests that resveratrol supplements do not benefit healthy people, says researcher Samuel Klein, MD, who directs the Washington University Center for Human Nutrition.
"There is no evidence that taking these supplements leads to better health in this population," he says.
For years, studies have suggested a link between drinking wine in moderation and reduced deaths from heart disease.
When researchers began trying to figure out why, they quickly focused on resveratrol, which is found in the skin of red grapes and some other fruits.
Even though few studies in humans have been done, sales of resveratrol supplements have risen to about $30 million a year, Klein says.
In their new study, Klein and colleagues recruited 29 postmenopausal non-obese women who were healthy.
For 12 weeks, half the women took supplements containing 75 milligrams of resveratrol a day and the other half took placebo pills.
To get the equivalent amount of the compound from wine, the women in the resveratrol group would have needed to have drunk 8 liters of red wine a day.
The researchers measured how well the women's bodies used insulin to control blood sugar.
None of the tests showed differences between the women who took the resveratrol supplements and those who did not.
The study was published online Wednesday and appears in the November issue of the journal Cell Metabolism.
Resveratrol supplements have shown benefits in small studies of obese men, patients with type 2 diabetes, and people who have trouble controlling their blood sugar.
But Klein says two of the three studies did not include a comparison group, which lowers the strength of the studies.
"Resveratrol supplementation may benefit these populations, but we cannot really say that without more definitive research," he says.
He adds that while resveratrol in pill form may not benefit healthy people, the compound still may be involved in the health-boosting benefits of red wine.
Preventive cardiologist Suzanne Steinbaum, MD, of Lenox Hill Hospital is not surprised by the findings.
She points out that the majority of studies examining the impact of nutritional supplements on health have been disappointing.