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Surprise finding shows popular antioxidant could undo exercise benefits

Kathleen Blanchard's picture
Resveratrol supplement could harm heart health finds surprising study.

Antioxidants are promoted for their health benefits and marketers are making a fortune tell us how we need to add more antioxidants to our diet. One such example is resveratrol that comes from red wine and grapes. A new study shows resveratrol can ham the heart. Before you go reaching for the latest antioxidant berry juice at the grocers, consider the fact that there is no hard evidence that we should be consuming antioxidants all day long anyway.

Resveratrol blocks benefits of exercise for heart health

Resveratrol it turns out can block a variety of heart benefits that come from exercise; found in a study of older men.

Researchers at the University of Copenhagen have found resveratrol, sold as a supplement, and touted as an anti-aging compound can have the opposite effect for lowering cholesterol levels and blood pressure and improving cardio-fitness.

The finding is contrary to animal studies that showed the red wine grape compound is beneficial for heart health.

Why we want some oxidation in the body

Research is emerging that we need some antioxidant stress to keep the body in balance, despite marketing that encourages us to buy resveratrol supplements and consume high levels of the free-radical scavengers.

Scientists have been trying to understand what leads to diseases. One theory is that oxidative stress is a major contributor.

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But research has never proven anti-oxidants can protect us from cancer or infection or even help us live longer. Some antioxidants – vitamin E and beta-carotene- have been linked to higher mortality rates, based on a Cochrane review.

Authors for the review concluded: “Antioxidant supplements need to be considered as medicinal products and should undergo sufficient evaluation before marketing”, which is an important note for consumers given the ‘push’ to get us to purchase the likes of resveratrol and other antioxidant drinks and supplements.

We know we need some oxidation in the body to help fight infection. Oxidation helps destroy unwanted bacteria and helps rid the body of cells that might turn cancerous.

Ylva Hellsten who led the investigation said in a press release: "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.”

For the study, published in the Journal of Physiology, researchers enrolled 27 healthy but inactive older men who engaged in a high-intensity exercise program for 8-weeks. Half of the men whose average age was 65 received placebo and the other half took 250 mg of resveratrol daily.

The finding showed exercise was beneficial for heart health in terms of lowering blood pressure, cholesterol levels and improving oxygen uptake. But when resveratrol was added to the men’s daily regimen, the antioxidant had the opposite effect.

Michael Joyner, from The Mayo Clinic USA, says the surprising finding on exercise and resveratrol highlights the need for more human studies. “Too often human studies focus on large scale outcomes and clinical trials and not on understanding the basic biology of how we adapt."

The study supports the notion that antioxidant supplements may not always be beneficial. The study authors note the dose of the red wine, grape compound given in the study might be higher than the average consumer would get from eating natural foods.

In this instance, resveratrol was found to have the opposite effect on heart health. That doesn't mean you should not eat foods that are healthy, but rather shows too many antioxidants in the form of supplements may be bad for health. It's also important to note more studies are needed to prove there is potential harm from resveratrol supplements.

Updated October 24, 2013