A red wine compound called resveratrol blocks many of the cardiovascular benefits of exercise in older men, a new study has claimed.
Resveratrol, found in red grapes and other plants, is considered a possible anti-ageing compound and is now widely available as a dietary supplement; much has been made of its role in explaining the cardiovascular health benefits of red wine, and other foods.
Now researchers at The University of Copenhagen surprisingly suggest that eating a diet rich in antioxidants may actually counteract many of the health benefits of exercise, including reduced blood pressure and cholesterol.
In contrast to earlier studies in animals in which resveratrol improved the cardiovascular benefits of exercise, this study in humans has provided strong evidence that in older men, resveratrol has the opposite effect.
The study suggests that reactive oxygen species, generally thought of as causing ageing and disease, may be a necessary signal that causes healthy adaptations in response to stresses like exercise. So too much of antioxidants in the diet may actually be detrimental to our health, researchers said.
Researchers studied 27 healthy, physically inactive men around 65 years old for eight weeks.
During the eight weeks all of the men performed high-intensity exercise training and half of the group received 250 mg of resveratrol daily, whereas the other group received a placebo pill (a pill containing no active ingredient).
"We found that exercise training was highly effective in improving cardiovascular health parameters, but resveratrol supplementation attenuated the positive effects of training on several parameters including blood pressure, plasma lipid concentrations and maximal oxygen uptake," said researcher Lasse Gliemann.
"We were surprised to find that resveratrol supplementation in aged men blunts the positive effects of exercise training on cardiovascular health parameters, in part because our results contradict findings in animal studies," said Ylva Hellsten, the leader of the project.
"It should be noted that the quantities of resveratrol given in our research study are much higher than what could be obtained by intake of natural foods," Hellsten said.
The research adds to the growing body of evidence questioning the positive effects of antioxidant supplementation in humans.
The study was published in The Journal of Physiology.
