A few weeks back I posted on antioxidants and how, for the most part, your body is actually pretty good at making its own antioxidants and/or acquiring them from a balanced diet based on real food. Within that post was a comment that not all oxidation needs to be suppressed, and in fact, degrees of oxidative stress are required to drive specific adaptations – within exercise and athletic endeavours, for example.
I have seen a couple of papers along these lines, but lukewarm off the twitter-feed is this latest one, which should at the very least cause pause for thought when evaluating whether you need the latest antioxidant supplement to combat the stress that you put your hard-working body under…
Antioxidant Supplementation during Exercise Training: Beneficial or Detrimental?
High levels of reactive oxygen species (ROS) produced in skeletal muscle during exercise have been associated with muscle damage and impaired muscle function. Supporting endogenous defence systems with additional oral doses of antioxidants has received much attention as a noninvasive strategy to prevent or reduce oxidative stress, decrease muscle damage and improve exercise performance.
Over 150 articles have been published on this topic, with almost all of these being small-scale, low-quality studies. The consistent finding is that antioxidant supplementation attenuates exercise-induced oxidative stress. However, any physiological implications of this have yet to be consistently demonstrated, with most studies reporting no effects on exercise-induced muscle damage and performance.
Moreover, a growing body of evidence indicates detrimental effects of antioxidant supplementation on the health and performance benefits of exercise training. Indeed, although ROS are associated with harmful biological events, they are also essential to the development and optimal function of every cell.
The aim of this review is to present and discuss 23 studies that have shown that antioxidant supplementation interferes with exercise training-induced adaptations. The main findings of these studies are that, in certain situations, loading the cell with high doses of antioxidants leads to a blunting of the positive effects of exercise training and interferes with important ROS-mediated physiological processes, such as vasodilation and insulin signalling.
More research is needed to produce evidence-based guidelines regarding the use of antioxidant supplementation during exercise training. We recommend that an adequate intake of vitamins and minerals through a varied and balanced diet remains the best approach to maintain the optimal antioxidant status in exercising individuals.
Not much point in blunting a training session by tipping large amounts of antioxidants down the throat is there?
Any idea as to the doses we’re talking about here?
I often take a packet of Emergen-C after training, the logic being that we burn through more than just energy during training, and this has me a little worried.
For the record, Emergen-C contains:
1000mg VitC
10mg B6
25mcg B12
And a bunch of other stuff in small quantities.
Not always antioxidants, but I tend to think it’s kind of funny that people take dietary supplements thinking that- not only will the compound of interest navigate the digestive system intact, but also that it will get to the site it’s wanted at. This is particularly true (in my mind) for joint supplements (especially since there’s not that much vasculature in joints anyway!) and in things that people want targeted to specific subcellular compartments (like ubiquinone, aka coenzymeQ to people in the nutritional realm (such a retro term!), that you want targeted to the mitochondria).
It seems much more useful to figure out what alters our endogenous production than to try and load the system dietarily. It’s not just about overall production, either. Pathologocial and environmental conditions can alter the subcellular distribution of antioxidants, so understanding when and how that occurs seems particularly useful. For example, I’m sad to report that chronic alcohol consumption decreases mitochondrial glutathione levels by inhibiting the transport of glutathione into the mitochondrial matrix (Of course, there’s also research out there showing that low levels of chronic alcohol consumption increase the ratio of reduced:oxidized cytosolic glutathione, suggesting that low level ethanol is an antioxidant… Oh the confusion!). In such a case, even if dietary glutathione was getting into the hepatocytes, it still wouldn’t make it to the mitochondria where it’s needed.
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Nonsensical.
If antioxidants are detrimental to exercise, kids which produce bunch of Q10 and animals which produce gram amounts of C daily would suck at sports, which is clearly what doesn’t happen.
Conclusions listed in some of those negative studies are mostly speculations (for instance in this one: http://www.pnas.org/content/early/2009/05/11/0903485106.abstract). Every day we have more studies showing beneficial or neutral action of antioxidants in relation to exercise (for instance http://goo.gl/nSnO1 http://goo.gl/wKH3g http://goo.gl/lwqEQ http://goo.gl/FYbFQ http://goo.gl/8XpCK http://goo.gl/7l4Ja http://goo.gl/eXAps http://goo.gl/Yd86w http://goo.gl/e5zvS http://goo.gl/6nKiH http://goo.gl/XAULH etc..)