Resveratrol: The New Weight-Loss Supplement?
Resveratrol and Weight Loss
For all the evidence, anecdotal and otherwise, about resveratrol's exercise benefits, manufacturers' claims that the supplement helps people lose or maintain weight are harder to substantiate. "From what I see on myresveratrolexperience.com, one of the primary reasons women in their 20s and 30s are taking it is that they think it'll help with weight loss," says Mark Swartz, who created the blog about two years ago to chronicle his and other people's experience with the supplement. Some proponents say it works in part by interacting with blood sugar. "Studies show that resveratrol boosts our muscles' ability to absorb glucose from food. This means that more calories go into muscles and fewer go into fat cells," Smoliga says. Indeed, research presented at a conference of the Endocrine Society showed that in the laboratory, resveratrol inhibited production of mature fat cells and hindered fat storage -- at least at the cellular level. In addition, a study found that mice fed a high-fat diet with resveratrol weighed almost the same as those served a non-high-fat diet without the supplement. But because, for some, resveratrol appears to increase the ability to exercise more frequently and intensely, it's hard to pin down the real source of weight maintenance.
Moreover, the supplement's long-term safety has yet to be proved. While one human study found that ingesting a one-time dose of up to five grams had no serious ill effects, that experiment lasted only a day. (Of course, most people who try resveratrol take more than one dose.) "The studies are too short," Sierra says. "We just don't have any data on long-term effects in people."Safety Concerns
Establishing supplement safety can take decades, and over time, in some cases, surprising dangers can be revealed. "Not long ago, vitamin E was all the rage," says Christopher Gardner, PhD, associate professor of medicine at Stanford University School of Medicine's Prevention Research Center. Vitamin E is an antioxidant thought to help protect against a range of diseases, like the hopes for resveratrol. But a 2005 report found that high doses of E could actually increase the risk of death. "It took 30 years to show that vitamin E supplements may have had negative effects in the large amounts that were often recommended," Gardner notes.
What is proved to be safe and healthy: consuming moderate amounts of natural sources of resveratrol. "Because of the unknowns, I'd rather people enjoy a glass of wine now and then instead of taking supplements," Gardner says. And research suggests that moderate amounts of wine can lower the risk of cardiovascular problems. Red wine has the highest concentration of resveratrol, with as much as 15 milligrams per bottle in types like pinot noir, depending on grapes, vineyard conditions, and other factors, but the content even in wine ranges widely; grape juice has about a half milligram per liter; and cranberries, blueberries, and peanuts contain trace amounts.
With no true consensus on the ideal amount of resveratrol necessary for measurable fitness perks, many experts advise women to proceed with caution. "Do you really want to experiment on yourself?" asks Sierra, who advocates getting in shape sans supplements. That opinion is shared by many FITNESS advisory board members we surveyed, including Jade Alexis, certified personal trainer and Reebok Global Instructor. "I typically frown on these seemingly quick, easy fixes," Alexis says. "I believe that eating right, exercising regularly, and getting sufficient sleep will keep us healthy."
Still, Rebecca, Hillary, and countless others are willing to take their chances. "I haven't experienced any downsides to resveratrol," Hillary says. "And I don't expect to, or I wouldn't be taking it and risking my body or my health."
"It's good to be cautious," adds Rebecca, who takes just 125 milligrams a day to hedge her bets. "I'm sensitive to drugs and supplements and have tried herbal products that have caused side effects, like making me dizzy. That's why I'm taking only a small dose of resveratrol. Even so, I think it may be helping me get the results I was looking for."
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