The Downfall of Resveratrol Supplements - They Block The Benefits of Exercise
Further to the ongoing evidence that continues to mount against poor quality supplements, new research shows that a high dietary intake of resveratrol from dietary supplements may counteract many of the cardiovascular benefits of exercise.
Through scientific research, the natural health supplement industry is gradually being exposed for low-grade raw materials with many studies now proving that inferior quality is causing health problems in high profile antioxidants.
The study data suggests that older men who consume high levels of the polyphenol - found in grapes and red wine, but also sold as supplements - may block the beneficial effects of exercise, including reducing blood pressure and lowering cholesterol, in older men.
Led by Lassa Gliemann from The University of Copenhagen, the research team noted that resveratrol has previously been suggested to have potent anti-aging effects - come of which were attributed to supposed cardiovascular benefits brought about by a high intake of the compound. However, the team noted that their results provide 'surprising and strong evidence' that resveratrol may in fact have the opposite effect when taken via specific supplementation.
"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," explained 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," commented Professor Ylva Hellsten - who coordinated the research.
"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," she said.
Gliemann and her colleagues studied 27 healthy, physically inactive men around 65 years old for 8 weeks.
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.
"The study design was double-blinded, thus neither the subjects nor the investigators knew which participant that received either resveratrol or placebo," explained the lead researcher, writing in the Journal of Physiology.
The supplements were not tested for impurities nor quality of resveratrol extracted.
The team reported that exercise training potently improved blood pressure, blood cholesterol, maximal oxygen uptake and the plasma lipid profile, but noted that resveratrol supplementation was found to reduce the positive effect of exercise training on blood pressure, blood cholesterol and maximal oxygen uptake.
"Whereas exercise training improved formation of the vasodilator prostacyclin, concomitant resveratrol supplementation caused a shift in vasoactive systems favoring vasoconstriction," the authors noted - adding that the supplementation did not affect the retardation of atherosclerosis.
"The present study is the first to demonstrate negative effects of resveratrol on training-induced improvements in cardiovascular health parameters in humans and add to the growing body of evidence questioning the positive effects of resveratrol supplementation in humans," commented Gliemann and her team.