Are you going overboard with your antioxidant use? drscottstevenson/forum/showthread.php?tid=173 There is a concept known as hormesis, a biological phenomenon, which proffers that (appropriate, generally small and more tolerable amounts of stress can elicit protective adaptations, whereas excessive stress is just that – excessive, potentially damaging and not optimal for generating adaptation(1, 2). It seems that free radical stress is an important part of the exercise stimulus, and one that is hormetic in nature. (I’m just considering endurance exercise right now.) When an antioxidant supplement like vitamin C is consumed, exercise adaptation may be prevented(3-5). As an example, daily supplementation with 1000mg of Vitamin C has been shown to prevent the normal increase in muscle mitochondria from endurance exercise(6). 1000mg of Vitamin C with 400IU of Vitamin E blocks the induction of endogenous (within the body) antioxidant defense systems, and even prevents the improvement in insulin sensitivity brought on by endurance exercise training(7). On the other hand, a smaller daily dosing of vitamin C (500mg with 400IU of vitamin E) did not impact improvement in VO2max (aerobic power) and mitochondrial density(8). Some dose-response relationship, relative to the free radical induced stress of the exercise stimulus, may dictate the extent to which antioxidant supplementation (or total dietary content) interferes with (endurance) training adaptation(2, 9). 1. Ristow, M. and K. Zarse, How increased oxidative stress promotes longevity and metabolic health: The concept of mitochondrial hormesis (mitohormesis). Experimental Gerontology, 2010. 45(6): p. 410-418. sciencedirect/science/article/pii/S0531556510001282 2. Finkel, T. and N.J. Holbrook, Oxidants, oxidative stress and the biology of ageing. Nature, 2000. 408(6809): p. 239-47. 3. Jackson, M.J., Free radicals generated by contracting muscle: by-products of metabolism or key regulators of muscle function? Free Radic Biol Med, 2008. 44(2): p. 132-41. 4. Gomez-Cabrera, M.C., et al., Moderate exercise is an antioxidant: upregulation of antioxidant genes by training. Free Radic Biol Med, 2008. 44(2): p. 126-31. 5. Powers, S.K., et al., Reactive oxygen species are signalling molecules for skeletal muscle adaptation. Exp Physiol, 2010. 95(1): p. 1-9. 6. Gomez-Cabrera, M.-C., et al., Oral administration of vitamin C decreases muscle mitochondrial biogenesis and hampers training-induced adaptations in endurance performance. The American Journal of Clinical Nutrition, 2008. 87(1): p. 142-149. ajcn.nutrition.org/content/87/1/142.abstract 7. Ristow, M., et al., Antioxidants prevent health-promoting effects of physical exercise in humans. Proc Natl Acad Sci U S A, 2009. 106(21): p. 8665-70. 8. Yfanti, C., et al., Antioxidant supplementation does not alter endurance training adaptation. Med Sci Sports Exerc, 2010. 42(7): p. 1388-95. 9. Ji, L.L., et al., Exercise and hormesis: activation of cellular antioxidant signaling pathway. Ann N Y Acad Sci, 2006. 1067: p. 425-35.
Posted on: Mon, 28 Oct 2013 19:31:02 +0000
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