Since decades the hymn on the healthiness of vitamins remained unquestioned. Recently a study was published in the highly acknowledged American journal “Proceedings of the National Academy of Sciences (PNAS)” that tells us another story. Vitamin C and E are well known antioxidants, which means scavengers of oxygen free radicals (ROS). All cells produce these molecules, and they produce more of this kind in case of stress. ROS are known for harming cells or even kill them. Over the years they developed into the culprit of every other disease. But this is only one side of the coin. “The other is that these molecules have got very positive properties,” so Prof. Dr. Michael Ristow from the Jena Institute of nutrition states. “Antioxidants can even harm health and undermine the positive effects of physical exercise on immunity.”, he says and the study confirms his proposition.
Endurance sport induces the production of ROS by increasing the activity of mitochondria. ROS activate the immune system, and support immune functions. This is one of the reasons why endurance sport is good for your health. Athletes love to take this vitamins to buffer these reactive oxygen species. They think that they can avoid cell destruction and speed up recovery. This view seems to be misleading. ROS are essential players within the body. Taking vitamins may counteract the bactericidal and immune stimulating effects of the ROS.
The study that was performed in 39 adult men proposes that Vitamin E and C may even harm well-being by inducing Diabetes Type-2. It seems that ROS counterbalance the insulin resistance that is observed during strenuous exercise in endurance athletes. ROS activate genes that balance insulin sensitivity in cells. Antioxidants suppress this gene activation.
The study underscores once and again that there is always more than one side to the coin, especially in biology. The body is a complex thing that escapes simple linearity. This study proves this again and thus, adds a serious aspect that deserves consideration. Noncritical intake of food supplements should be questioned.
Ristow M, Zarese K, Oberbach A, et al.: Antioxidants prevent health-promoting effects of physical exercise in humans. PNAS, March, 2009
