Antioxidants block gains from endurance training
Another study on antioxidant supplements, this one from researchers at the University of Queensland in Australia, published online in Medicine & Science in Sports & Exercise.
The study was with rats: 14 weeks of supplementation with vitamin E and another antioxidant called alpha-lipoic acid, training four times a week. The antioxidants suppressed the growth of new mitochondria (the “power plants” of your cells), which is one of the primary adaptations to endurance training. One of the new wrinkles to this study compared to previous ones is that growth of mitochondria was suppressed even in rats that weren’t training, if they took the supplements.
I’ve written several times before about this area of research. The idea is that “reactive oxygen species” (ROS) are generally bad, and antioxidants fight them. But when you exercise, the ROS you produce are the “signals” that tell your body to adapt, so if you take antioxidants, your body doesn’t realize it’s supposed to adapt and get stronger (or grow more mitochondria or whatever).
The conclusions are far from clear — for instance, this study didn’t find any reduction in the benefits of endurance training from antioxidants. But given how little evidence there is that these types of supplements actually help, the potential costs certainly seem to outweigh the benefits.