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Antioxidant Supplements: Too Good to Be True?

Antioxidant Supplements: Too Good to Be True?

Taking antioxidant supplements when exercising could do more harm than good.


“Boost your health and stave off age-related problems by taking a daily dose of antioxidants.” We’ve all heard it before, but are these supplements really all they’re cracked up to be? Recent research at The University of Copenhagen provides evidence that such supplementation blocks the cardiovascular benefits of exercise in older men.

Oxygen is key to our survival. However, one of the by-products of oxygen usage in our bodies is free radicals. Free radicals are as good as they are bad. At low doses they help us fight infections, but at high doses these highly reactive molecules cause oxidative damage to our proteins and genes. As a defence mechanism, our bodies produce antioxidants to ‘mop up’ the free radicals to maintain a healthy state. Free radical production can be enhanced by environmental factors such as smoking, pollution, diet and UV radiation which can in turn contribute to ageing and disease.

Physical exercise can also increase free radical production. The antioxidant-exercise hypothesis suggests this is due to enhanced oxidation triggered by increased breathing rate. Would it therefore not be desirable to boost an individual’s natural antioxidant defence system to prevent such damaging effects of exercise and perhaps enhance the cardiovascular benefits?

Studies have shown that a diet rich in foods with high antioxidant content is associated with a multitude of health benefits. Antioxidants include beta-carotene, vitamin D and resveratrol to name but a few. The latter is a natural antioxidant compound found in red grapes and thus red wine. Numerous studies examining the effects of this compound on exercising animals have shown that it increases the cardiovascular benefits of exercise. Resveratrol has since become a widely used dietary supplement to not only athletes but also to those who hope to delay the detrimental effects of ageing. According to a pivotal study conducted at The University of Copenhagen, we may have jumped the gun.

The study comprised of 27 healthy and physically-inactive aged men (65 ± 1 years). For the duration of 8 weeks, all men underwent high-intensity exercise training. During this period, 14 men took a daily dose of 250 mg resveratrol whilst the remaining 13 men took a placebo. Cardiovascular parameters including blood pressure, cholesterol and maximal oxygen uptake improved in the placebo group, but the majority of these positive effects of exercise were abolished in the resveratrol group.

Rather than being detrimental, the production of free radicals during physical exercise may be a favourable, adaptive response to the stresses of exercise. The dose of resveratrol administered daily in this study is far higher than what can be acquired through diet. It is possible that such a high dose ‘mops up’ too many free radicals, resulting in the loss of cardiovascular benefits of exercise. So, instead of reaching for the supplement bottles on the shelf, eat a healthy diet rich in fruit and vegetables. A glass of my favourite red wine has never been so appealing. Cheers!

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Reference: Gliemann, L., Schmidt, J.F., Olesen, J., Biensø, S.U., Mortensen, S.P., Nyberg, M., Bangsbo, J., Pilegaard, H. and Hellsten, Y. (2013). Resveratrol blunts the positive effects of exercise training on cardiovascular health in aged men The Journal of Physiology DOI: 10.1113/jphysiol.2013.258061

resveratrol benefits,antioxidants and exercise, resveratrol antioxidant supplements, antioxidant exercise

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