Researchers at the Institute of Genetics and Molecular and Cellular Biology in Illkirch, France have found that resveratrol boosts the exercise capacity of muscles in mice and protects against diet-induced insulin resistance and obesity. The research was published online on November 16, 2006 in the journal Cell.
Johan Auwerx and colleagues gave mice 200 or 400 milligrams per kilogram resveratrol daily combined with a high fat diet or regular chow diet for fifteen weeks. Mice who received the chow combined with resveratrol tended to gain less weight than animals who did not receive the compound. Predictably, mice who received the high fat diet gained significantly more weight than mice on the regular chow, yet those who received resveratrol weighed almost the same as mice on the unsupplemented chow diet over the course of the study.
The researchers determined that the decrease in weight was due to a reduction in body fat, with resveratrol-fed mice having smaller fat cells than those who did not receive it. This finding was not due to a decrease in food intake, as all mice on the high fat diet were found to have consumed a similar amount of calories per day, and had similar fecal lipid content. It was discovered that animals who received resveratrol had greater energy expenditure, with enhanced mitochondrial activity in brown adipose tissue and muscle. In an endurance test, mice who received resveratrol were able to run twice the distance that untreated mice ran before experiencing exhaustion. Similar results were obtained for endurance tests conducted with the groups who were fed the chow diets, showing that the significant difference in weight among the high-fat diet groups was not a factor in the increased resistance to muscle fatigue experienced by resveratrol-fed mice.
Although fasting glucose levels were not affected by resveratrol administration, mice that received the compound had significantly reduced fasting insulin levels, indicating improved insulin sensitivity. In another experiment with genetically obese mice on high fat diets, resveratrol improved glucose tolerance and fasting glucose levels without affecting weight, which suggests that resveratrol’s antidiabetic effects may be independent of its effects on body weight.
In agreement with previous research, the team concluded that resveratrol increases the activity of the gene Sirt1, which has been associated with increased life span. In an experiment with humans, they demonstrated an association between genetic variation in the Sirt1 gene and whole body energy expenditure.
“This work is significant because it shows that a SIRT1 activator can protect against metabolic disease, highlighting the therapeutic potential of sirtuins,” Dr Auwerx stated. “Resveratrol, a compound found in the skin of red grapes and hence in red wine, could very well explain the French Paradox.”
Source: Life Extension