Resveratrol: The New Weight-Loss Supplement?
Resveratrol's Get-Fit Promise
Fitness experts started to take notice of resveratrol in 2006, when the journal Cell reported that mice given the antioxidant ran nearly twice as far on a treadmill as unsupplemented critters. The treatment "significantly increases the animal's resistance to muscle fatigue," researchers concluded. Translation: More energy and less muscle exhaustion led to a better workout. "It's as if you could put the benefits of a healthy diet and exercise in a pill," Smoliga says.
The hypothesis? Resveratrol stimulates enzymes called sirtuins, which control important functions throughout the body, including DNA repair, cell life, aging, and fat production. "Sirtuins may also increase mitochondria, the powerhouses inside cells where nutrients and oxygen combine to make energy," says Felipe Sierra, PhD, director of the division of aging biology at the National Institute on Aging at the National Institutes of Health. Sure enough, mice on resveratrol had bigger, denser mitochondria, so their charged muscles were better able to use oxygen. In theory, this means that resveratrol may be able to help you work out longer or harder or both before your muscles become too fatigued to perform. These more intense workouts will then condition muscles for even greater effort the next time you lace up, for a continuous cycle of improved fitness.
Again, research outside the laboratory has been limited: In one of the few completed human trials, 90 sedentary men and women were given a resveratrol-based cocktail or placebo daily for 12 weeks. After three months, everyone jumped on treadmills. "While they all hit the same levels of intensity, the resveratrol group exerted less effort while exercising," says Smoliga, who led the study. What's more, they also had significantly lower heart rates during exercise -- the equivalent of the results of three months' light to moderate training -- apparently just from taking the daily supplement.
Hillary Hallows, a 33-year-old sales and marketing executive in Phoenix, can relate. She started using resveratrol about four months ago after hearing about it from a client. "My friend was getting great results, and I trusted her. Plus, I wanted to get more out of my workouts and have extra energy," she says. As with the human trial results, Hillary found that she could push herself further with less effort. "I hike at least three times a week and walk my dogs twice a day, and have found that I'm much less tired afterward," she says. "I have a long day -- I'm up at 5 a.m. and in bed at 11 p.m. -- and I used to feel pretty wiped after a hike or at the end of the day." Not anymore. A plausible explanation: Her resveratrol-primed muscles are using oxygen more efficiently than they used to.
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