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Antioxidant Supplements are Unnecessary for Most People

Some believe supplemental antioxidants, like vitamin C and vitamin E, can enhance adaptation to exercise. On the surface, this makes sense. Physical exercise creates reactive oxygen species (ROS), a signaling pathway important biological and physical adaptations to training (Mankowski, Anton, Buford, & Leeuwenburgh, 2015). Overproduction of ROS, can cause cellular damage through ROS interfering with the phospholipid bilayer of the cell membrane (McBride & Kraemer, 1999) Vitamin C and E are antioxidants, meaning they both limit the accumulation of oxidative stress by limiting the amount of ROS produced (Mankowski et al., 2015). Taking a vitamin C or vitamin E supplement before or after a bout of exercise that causes a build up of oxidative stress should be beneficial in improving exercise adaptations, but research does not support that conclusion.

Vitamin C and E supplementation may hamper cellular adaptations to endurance training. Paulsen et al. (2014) used a double-blind study on 54 participants to examine the effects of vitamin C and vitamin E supplementation on endurance training adaptations. Subjects were given either two pills containing vitamin C and vitamin E 1-3 hours prior to training and 1 hour after training or a placebo. Endurance training was consistent for both groups, took place over an 11 week period and consisted of continuous long distance training and interval training (Paulsen et al., 2014) Muscle biopsies were taken after the training period to examine cellular adaptations. The data suggests that vitamin antioxidant supplementation blunts mitochondrial biogenesis, by lessening the creation of ROS, thereby inhibiting the redox-signaling and the induction of certain genes like PGC-1, which is responsible for mitochondrial transcription (Paulsen et al., 2014). Cells need a certain amount of ROS to cause cellular adaption, and antioxidants prevent or lessen mitochondrial biogenesis, potentially reducing exercise capacity.

In a review by Merry and Ristow (2016) explain that a certain amount of ROS is necessary for managing insulin sensitivity, mitochondrial biogenesis, immune response, and growth factor signaling. Normal amounts of exercise produces the right amount of oxidative stress optimal for muscle and performance function, whereas too much can be harmful. Vitamin C and vitamin E can lessen the cells adaptations due to physical exercise, making the cells less tolerable to increased stress (Merry & Ristow, 2016). Large doses of vitamin C and vitamin E reduces the ROS created by exercise, and prevents signaling of the adaptations of mitochondrial biogenesis, muscle growth, and insulin sensitivity.

For normal recreational athletes or occasional weightlifters, antioxidant supplements do not seem to be helpful in maximizing adaptations. The ROS from exercise is needed to cause cellular adaptions, and vitamin C and vitamin E decrease the amount of ROS produced, which interferes with the necessary signaling. Supplementation of vitamin C and vitamin E seems to lessen cellular adaptations associated with exercise and is most likely unnecessary in mega-doses.


Mankowski, R. T., Anton, S. D., Buford, T. W., & Leeuwenburgh, C. (2015). Dietary antioxidants as modifiers of physiologic adaptations to exercise. Medicine & Science in Sports & Exercise, 47(9), 1857-1868.

McBride, J. M., & Kraemer, W. J. (1999). Free radicals, exercise, and antioxidants. Journal of Strength and Conditioning Research, 13(2), 175-183.

Merry, T. L., & Ristow, M. (2016). Do antioxidant supplements interfere with skeletal muscle adaptation to exercise training? The Journal of Physiology, 594(18), 5135-5147.

Paulsen, G., Cumming, K. T., Holden, G., Hallén, J., Rønnestad, B. R., Sveen, O., . . . Raastad, T. (2014). Vitamin C and E supplementation hampers cellular adaptation to endurance training in humans: A double-blind, randomised, controlled trial. The Journal of Physiology, 592(8), 1887-1901.