What You DON’T Need in a Supplement Product, Part 1: Anti-Oxidants
Very few buzzwords are more effective from a marketing standpoint than the term “anti-oxidant”. Store shelves are stocked full of products, ranging from fruits and berries to all forms of herbal supplements, that proudly boast of their anti-oxidant powers. Anti-oxidants, which include vitamins C and E as well as beta carotene and many others, are touted by marketers as having health benefits across a broad spectrum of disease and health conditions.
And the situation is no different in the sports supplement world. Supplements are used widely by athletes throughout nearly all sports, and anti-oxidants are frequently included in such products, the rationale being that muscle damage can be attenuated and the immune system can somehow be “enhanced” by boosting one’s anti-oxidant status to supra-normal levels.
But as with all catchphrases and marketing buzzwords, where is the evidence or even the physiology to support these claims?
Anti-oxidants represent a defense mechanism of your body against what are called “reactive oxygen species” (ROS), which are chemically reactive molecules containing oxygen. ROS can be the result of external forces, such as tobacco, radiation, pollutants, etc, but are also produced endogenously by your body as part of its normal aerobic metabolism.
Once formed, ROS can then initiate a chain reaction within the cells of your body, targeting proteins, lipids, and DNA, among other things, for damage and destruction. Protein function can be impaired in multiple ways, as transcription can be inhibited and the protein structure itself can be altered (5).
However, the effects of ROS are not always harmful. ROS serve many beneficial, and in fact essential, functions throughout your body. For example, ROS play a critical role in the inflammatory response and in many intracellular signaling pathways (6).
This dual nature of ROS is important to understand when considering whether or not to incorporate anti-oxidants into a sports nutrition plan. The muscles of your body undergo a series of complex processes to repair themselves after a physical stress, and ROS play a significant part of this process. Similarly, ROS are an important part of your body’s inflammatory response. So the thought that somehow you are “enhancing” the immune system by suppressing the generation of ROS may represent a faulty line of reasoning.
But as always, whenever there is controversy, the next step is to ask “what does the evidence tell us?”.
The evidence has been equivocal at best. The majority of studies have looked at secondary indicators of muscle damage, such as muscle soreness, rather than how well the muscles adapt and perform in the days to weeks following exercise. However, even despite this, the studies have generally produced negative results (8).
Indicators of muscle damage after exercise do not necessarily signify a detrimental process. The better question to ask is, how does supplementation influence how well the muscles recover and evolve following exercise. And the evidence does not seem to support the notion that anti-oxidants are beneficial in this process. Peternelj et al (2) performed a great review regarding this specific question. They looked at 23 separate studies which overall indicate that anti-oxidant supplementation actually interfered with beneficial exercise-associated training adaptations. You may be, in fact, hindering, not helping, the recovery process with anti-oxidant supplementation.
And there are legitimate worries with regards to overall health. Several meta-analyses (3, 4, 7) have reviewed the efficacy of anti-oxidant supplementation on the risk of cardiovascular disease and mortality. Not only have such studies failed to show a benefit, but some in fact appeared to demonstrate a mortality increase, particularly with the use of beta carotene (3) and high dose vitamin E (7).
There are, of course, certain studies which, conversely, seem to indicate a benefit, both in performance and in health. It is possible, for example, that it is just a question of appropriate dosing, that there is a biphasic response where lower doses yield beneficial effects but higher doses are detrimental. This concept is known in toxicology as hormesis (9).
It is also possible, though, that the studies showing benefit did so simply by random chance. The overwhelming number of negative studies cannot be ignored. In science, it is never about about one study taken in isolation. What matters is what the preponderance of evidence indicates. You cannot pick and choose data if you want to arrive at the truth.
And looking at the evidence as a whole, anti-oxidants have not been shown to lead to a performance benefit in endurance exercise. Nor have they convincingly been shown to accelerate recovery. In fact, a significant amount of evidence indicates the opposite. And there are even potential concerns for long-term health with higher doses.
Stick with what works, not what sounds good from a marketing standpoint. Anti-oxidants should not be a routine component of sports supplement products.
1. Heneghan C, Howick J, O’Neill B, Gill PJ, Lasserson DS, Cohen D, Davis R, Ward A, Smith A, Jones G, Thompson M. The evidence underpinning sports performance products: a systematic assessment. BMJ Open. 2012 Jul 18;2(4).
2. Peternelj TT, Coombes JS. Antioxidant supplementation during exercise training: beneficial or detrimental? Sports Med. 2011 Dec 1;41(12):1043-69.
3. Vivekananthan DP, Penn MS, Sapp SK, Hsu A, Topol EJ. Use of antioxidant vitamins for the prevention of cardiovascular disease: meta-analysis of randomised trials. The Lancet. Volume 361, Issue 9374, 14 June 2003, Pages 2017–2023
4. Myung SK, Ju W, Cho B, Oh SW, Park SM, Koo BK, Park BJ; Korean Meta-Analysis Study Group. Efficacy of vitamin and antioxidant supplements in prevention of cardiovascular disease: systematic review and meta-analysis of randomised controlled trials. BMJ. 2013 Jan 18;346:f10.
5. Davies KJ. Protein Damage and Degradation by Oxygen Radicals 1: General Aspects. J Biol Chem. 1987 Jul 15;262(20):9895-901.
6. Valko M, Leibfritz D, Moncol J, Cronin MT, Mazur M, Telser J. Free radicals and antioxidants in normal physiological functions and human disease. Int J Biochem Cell Biol. 2007;39(1):44-84.
7. Miller III ER, Pastor-Barriuso R, Dalal D, et al. Meta- analysis: high-dosage vitamin E supplementation may increase all-cause mortality. Ann Intern Med 2005 Jan 4; 142 (1): 37-46
8. McGinley C, Shafat A, Donnelly AE. Does antioxidant vitamin supplementation protect against muscle damage? Sports Med. 2009;39(12):1011-32.
9. Mattson MP. Hormesis defined. Ageing Res Rev. 2008 Jan;7(1):1-7.