12 January - 20 June 2016

Resveratrol may block benefits of exercise

31 July 13

Gliemann et al. from the University of Copenhagen have studied the effects of resveratrol on cardiovascular health in ageing men.  Resveratrol is a polyphenol, found naturally in the skin of red grapes and has been shown to exhibit antioxidant behaviour.  As such it is taken by some people as a health supplement to help slow the process of ageing.  Previous research involving rodents has found that resveratrol enhances training-induced changes in cardiovascular function, exercise performance and the retardation of atherosclerosis. The study published in the Journal of Physiology investigated whether humans had similar reactions using aged men.  In humans resveratrol has been shown to improve metabolic function of obese men although recent studies have contradicted this finding.  Although the effects of resveratrol on cardiovascular health have been examined in rats, few studies have been conducted on humans and to date no study has examined the combined effect of exercise training and resveratrol on vascular function in aged humans. Gliemann et al recruited 27 men aged 60-72 who were physically inactive, doing less than 2 hours per week of moderate physical activity, but otherwise healthy.  For 8 weeks the men took either 250mg of resveratrol or a placebo in the double-blind randomized study.  During the intervention period the participants performed high-intensity exercise training.  Results showed the opposite effect compared to the rats. In fact there was a ‘45% greater increase in maximal oxygen uptake in the placebo group than in the resveratrol group.’  Resveratrol supplementation was also found to reduce the positive effect of exercise training on blood pressure, blood cholesterol, and did not affect the retardation of atherosclerosis.  The study notes that “whereas exercise training improved formation of the vasodilator prostacyclin, concomitant resveratrol supplementation caused a shift in vasoactive systems favouring vasoconstriction.”  The paper discusses a number of possible explanations including that reactive oxygen species, generally thought of as causing aging and disease, may be a necessary signal that causes healthy adaptations in response to stresses like exercise. The authors note that although the quantities of resveratrol used in the study are much higher than what could be obtained by intake of natural foods, their research adds to the growing body of evidence questioning the positive effects of antioxidant supplementation in humans.

RSSL's Functional Ingredients Laboratory is happy to discuss the analysis of resveratrol with clients. For more information please contact Customer Services on Freephone 0800 243482 or email enquiries@rssl.com.

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