Beauty Health for Life

In older men, a natural antioxidant compound found in red grapes and other plants -- called resveratrol -- blocks many of the cardiovascular benefits of exercise, according to research published today [22 July 2013] in The Journal of Physiology.

Resveratrol has received widespread attention as a possible anti-aging 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. But now, new research at The University of Copenhagen surprisingly suggests 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 surprising and strong evidence that in older men, resveratrol has the opposite effect.

What is emerging is a new view that antioxidants are not a fix for everything, and that some degree of oxidant stress may be necessary for the body to work correctly. This pivotal study suggests 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. So too much of a good thing (like antioxidants in the diet) may actually be detrimental to our health.

Lasse Gliemann, a PhD student who worked on the study at The University of Copenhagen, explains how they conducted the research, and the results they found: "We 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 (a pill containing no active ingredient). The study design was double-blinded, thus neither the subjects nor the investigators knew which participant that received either resveratrol or placebo.

"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."

Ylva Hellsten, the leader of the project, says:"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.

"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."

This research adds to the growing body of evidence questioning the positive effects of antioxidant supplementation in humans.

Michael Joyner, from The Mayo Clinic USA, says how the study has wider implications for research: "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."

Physical activity decreases the risk of sudden cardiac death in unfit men, reveals research presented at the ESC Congress today by Dr Jari Laukkanen and Dr Magnus Hagnas from Finland.

Dr Laukkanen said: "Sudden cardiac death (SCD) accounts for approximately 50% of deaths from coronary heart disease. SCD typically occurs shortly after the onset of symptoms, leaving little time for effective medical interventions, and most cases occur outside hospital with few or no early warning signs. Finding ways to identify individuals at elevated risk of SCD would allow early interventions on risk factors to be implemented." The current study investigated the impact of high leisure-time physical activity (LTPA) combined with cardiorespiratory fitness (CRF) on risk of SCD. It included 2,656 randomly selected men aged 42 to 60 years from the Kuopio Ischemic Heart Disease Risk Factor Study, a Finnish study of risk predictors for cardiovascular outcomes and SCD in the general population. Baseline cycle exercise test and risk factor assessment were performed in 1984-89. SCD was defined as death with cardiac origin within 24 hours after onset of symptoms.

LTPA was assessed using a 12-month physical activity questionnaire. One third of subjects had low LTPA (energy consumption <191 kcal/day, equal to around 35 minutes of slow walking or 25 minutes of jogging for a 70 kg male). CRF was assessed with a maximal symptom limited cycle exercise test and peak oxygen uptake was calculated in metabolic equivalents (MET). One third of men had a low CRF (<7.9 METs).

For the analyses the study population was divided into 4 groups: 1) high CRF and high LTPA, 2) high CRF and low LTPA, 3) low CRF and high LTPA and 4) low CRF and low LTPA. Group 1 was used as a erence. The risk of SCD was adjusted for previously established cardiovascular risk factors (age, smoking, alcohol consumption, body mass index, systolic blood pressure, low density lipoprotein cholesterol, C-reactive protein, prevalent type 2 diabetes and previously diagnosed coronary heart disease).

During the mean 19 years of follow-up 193 SCDs occurred. There was a 2-fold increased risk of SCD in men with low CRF and LTPA (group 4, see figure) compared to men with high CRF and high LTPA (hazard ratio [HR] 2.0, 95% confidence interval [CI] 1.3-2.9). Men with low CRF and high LTPA (group 3) did not have a statistically significant increased SCD risk compared to men with high CRF and high LTPA (HR 1.3, 95% CI 0.9-1.8). Dr Laukkanen said: "This indicates that a higher amount of leisure-time physical activity might reduce the risk of SCD among men with low cardiorespiratory fitness."

The amount of LTPA did not affect the risk of SCD among the men with high CRF (groups 1 and 2). Dr Laukkanen said: "Our study shows that CRF is a risk factor for SCD. High leisure-time physical activity exerts a protective effect on the risk of SCD among men with low cardiorespiratory fitness but does not affect risk in men with high baseline CRF."

He added: "It is widely believed that the level of CRF is determined by physical exercise, genetics and other lifestyle factors. Our study shows that exercise training and LTPA may be especially important in individuals with low CRF. One possible explanation is that CRF can be improved with regular exercise training."

Dr Laukkanen concluded: "The importance of CRF has often been neglected in the equation of SCD risk, despite appearing to be one of the most important correlates of overall health status. Our study emphasises the importance of regular physical exercise, especially among men with low CRF. An exercise test could be used to identify individuals with low CRF and high risk of SCD, who should then be urged to exercise more."