The antioxidant resveratrol — found in grapes and wine — has been shown to benefit heart health in a range of studies. But new research suggests that, in older men at least, high doses of the compound can be too much of a good thing and can actually increase cardiovascular risks.
 

The new study, published in the Journal of Physiology, indicates the natural antioxidant can block many of the cardiovascular benefits of exercise. The bottom line: Antioxidants are not a fix for everything and that some degree of oxidant stress may be necessary for the body to work correctly and can prompt healthy responses to it, said researchers from the University of Copenhagen who conducted the study.

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Resveratrol, available as a supplement, has been hailed by health experts as a possible anti-aging compound and heart-healthy agent that may account for the benefits of red wine and other foods. But the new research suggests eating a diet rich in antioxidants may actually counteract many of the health benefits of exercise, including reduced blood pressure and cholesterol, particular in older men.
 

Lead researcher Lasse Gliemann said the new findings are based on an analysis of more than two dozen men who took resveratrol supplements.
 

"We studied 27 healthy, physically inactive men around 65 years old for 8 weeks," Gliemann said. "During the 8 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 …
 

"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."
 

Michael Joyner, from the Mayo Clinic, said the study has significant implications: "In addition to the surprising findings on exercise and resveratrol, this study shows the continuing need for mechanistic studies in humans. Too often human studies focus on large-scale outcomes and clinical trials and not on understanding the basic biology of how we adapt."