Antioxidants. Technical Document

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1 Antioxidants Technical Document Developed by INDI/SNIG for the Irish Sports Council 2012

2 Table of Contents Introduction 3 The athletic benefits of consuming antioxidant supplements 4 Concerns with antioxidant supplementation 4 Summary 5 Notes 5 References 6 2

3 Introduction Antioxidants are vitamins, minerals or enzymes that can be produced by the body or introduced into the body through dietary means. The main dietary sources, the best sources for obtaining antioxidants, are plant-based foods including dark coloured vegetables e.g. broccoli, fruits, berries, legumes, nuts, grains, seeds and oils (AIS Sports Nutrition). Other sources include both black and green tea which are rich sources of flavonoids. Some alternative preparations that purport to have antioxidant benefits include Co enzyme Q10, Quercetin, Rhodiola rosea L., Cucumis melo LC., and Lemon verbena extract to name a few. Antioxidants protect cells from the inevitable production of free radicals, which occurs during normal metabolism and leads to the formation of reactive oxygen species (ROS) or reactive nitrogen species. Physical exercise induces a significant increase in oxygen uptake. Mitochondria, the organelles that provide energy (ATP) to cells, are the main source of ROS production (Powers et al. 2008, Williams et al. 2006, Aguiló et al. 2004). The temporary increase in ROS production during exercise can lead to oxidative stress, which occurs when tissues antioxidant defence systems are overwhelmed by high levels of ROS production (Sen 2001). Muscle damage during physical exercise may further increase ROS formation by activating phagocytic cells (Nikolaidis et al. 2008). Oxidative stress has been linked to cardiovascular disease, neurodegenerative diseases and some cancers (Williams et al. 2006, Basarici et al. 2008, Chan et al. 2008). There is some evidence that suggests an association between exercise-induced oxidative stress and disease in people who partake in large amounts of physical activity (Paffenbarger et al. 1986, Quinn et al. 1990, Shaper et al. 1991, Lee et al. 1995). Many athletes consume antioxidant supplements, predominantly in the forms of vitamins C and E, in the belief that they will reduce oxidative stress. While excessive ROS can exert harmful effects within skeletal muscle during exercise, lower levels are crucial for adaptation of metabolic and signalling pathways in response to exercise (Newsholme et al. 2011). There are a number of scientific reviews on the use of antioxidants as a means of decreasing oxidative stress and the possibility of preventing muscle damage (Peternelj and Coombes, 2011; ; McGinley et al. 2009), Stear et al Paternelj and Coombes (2011) concluded loading the cell with high doses of antioxidants leads to a reduction of the positive effects of exercise training and interferes with important ROS -mediated physiological processes, such as vasodilation and insulin signalling. More research is needed to produce evidence-based guidelines regarding the use of antioxidant supplementation during physical exercise. An adequate intake of vitamins and minerals through a varied and balanced diet remains the best approach to maintain the optimal antioxidant status. Nieman et al. (2012) conducted a review of the use of Quercetin, Resveratrol and Rhodiola rosea and concluded that more research is necessary to determine if these compounds benefit athletic performance. Previously, Stear et al. (2009) conducted a brief review and concluded that there is limited scientific evidence to recommend antioxidant supplementation. Conflicting scientific evidence as to the possible benefits and detriments athletes may experience from antioxidant supplementation does not enable health professionals to make specific supplementation recommendations. ROS are produced when the muscle eccentrically contracts, so it has been proposed that antioxidant supplementation may assist with preventing muscle damage. A review by McGinley et al. (2009) assessed the premise that antioxidant supplementation decreases muscle damage. Overall, the conclusion is that there is insufficient evidence to suggest that antioxidants, though they assist with reducing oxidative stress, are effective for protecting against muscle damage (McGinley et al. 2009). 3

4 Williams et al. (2006) reviewed the impact of antioxidant supplementation on oxidative stress in endurance athletes and summarised research investigating the effect of antioxidants on oxidative stress. This review concluded that there is not enough scientific evidence to recommend antioxidant supplementation for endurance athletes (Williams et al. 2006). These reviews, albeit a small selection of the many available, provide a solid information base in regards to the underlying mechanisms of antioxidants, their use within sport, purported benefits and conclusions in regards to their use. Overall there is no consistent evidence that suggests antioxidant use in athletes enhances performance or prevents muscle damage, and the consumption of excessive amounts of antioxidants may lead to long term health side effects effects (Peternelj and Coombes 2011; Stear et al. 2009; McGinley et al. 2009; Williams et al. 2006; Sen, 2001). The athletic benefits of consuming antioxidant supplements The two main proposed benefits from consuming antioxidants include decreasing muscle damage (McGinley et al. 2009) and combating free radical damage during exercise, therefore possibly preventing muscle fatigue (Powers et al. 2008). Many athletes therefore consume antioxidant supplements in a bid to prevent oxidative stress and possibly maintain muscular power output. Many other studies have assessed possible antioxidant benefits from a range of different preparations in athletes. Some of these include: Moderate antioxidant supplementation with lemon verbena extract (containing 10% verbascoside) did not block the cellular adaptive response to exercise, reduced oxidative damage of neutrophils and reduced signs of muscular damage in chronic running exercise (Funes et al. 2011) When consumed prior to altitude training, antioxidant supplementation (combination of betacarotene, alpha-tocopherol acetate, ascorbic acid, selenium, and zinc) can improve ventilatory threshold after acute (but not chronic) altitude exposure (Subudhi et al. 2006) Supplementation with superoxide dismutase (SOD) rich Cucumis melo LC. (SOD is a key component of the intracellular antioxidant system) promoted antioxidant status and protected against increased inflammation in the serum in professional rowers but had no effect on oxidative damage induced by exhaustive exercise (Skarpanska-Stejnborn et al. 2011) Similarly, supplementation with Rhodiola rosea L. (a perennial herb which claims antioxidant properties in traditional medicine) increased antioxidant levels in the plasma of professional rowers but had no effect on oxidative damage induced by exhaustive exercise (Skarpanska-Stejnborn et al. 2009) Supplementation with Vitamin C (500mg) and Vitamin E (400 IU) in trained and previously untrained individuals did not increase insulin sensitivity or expression of transcriptional and anti-oxidant proteins abolishing the health promoting of exercise observed in the control group (Ristow et al. 2009) Oral quercetin supplementation, (a flavanol with purported antioxidant properties) did not alter blood plasma lipid or aqueous-phase antioxidant capacity or oxidative damage during an ultramarathon challenge (Quindry et al. 2008) Though there is limited evidence that antioxidant supplementation will enhance performance through decreasing muscle fatigue, the one circumstance that may justify the use of antioxidant supplements is in athletes who have a less than adequate diet and may be deficient in particular vitamins and minerals (Stear et al. 2009). Similarly when considering supplementing antioxidants, only a blood test can identify actual deficiencies. 4

5 Concerns with antioxidant supplementation There is evidence that excessive antioxidant consumption can prevent skeletal muscle adaptations as ROS are involved in the expression of many skeletal muscle proteins. As reported by Stear et al. (2009) recent studies have demonstrated that high consumption of Vitamins C and E can preclude the training and health promoting adaptations of exercise (Ristow et al. 2009, Gomez-Cabrera et al. 2008). Ristow et al. (2009) proposed that ROS production from exercise is essential for promoting insulin sensitivity in humans. This finding may be particularly important for individuals who have diseases such as diabetes. There is also a meta-analysis (Bjelakovic et al. 2007) that reports excessive antioxidant supplementation does not improve health outcomes and may increase mortality. Summary Taking into consideration all currently available literature, particularly from review articles, there is not sufficient evidence for the general recommendation of antioxidant supplementation in athletes. There appears to be a greater slant towards advising athletes against antioxidant supplementation, if after nutritional assessment their reported food intake is rich in antioxidant foods. Supplementation should therefore be recommended only if a blood test identifies a specific nutrient deficiency, and foods rich in antioxidants recommended instead. A balanced diet including a variety of fruits and vegetables remains the best nutritional approach to maintain optimal antioxidant status. Notes Pubmed (Medline), SPORTDiscus and Cochrane library were searched for all human studies published in peer reviewed journals. The terms searched were antioxidant supplements AND exercise and antioxidant supplements AND sport and antioxidant supplements AND athletes. Studies included in this review adhered to the following criteria: Inclusion criteria Human studies published in English Healthy subjects Original investigations assessing the use of antioxidant supplements and/or exercise Incorporated the use of an indistinguishable placebo Exclusion Criteria Qualitative studies assessing the prevalence of supplement use in both the general and athletic population Methods for assessing oxidative damage After title and abstract review, six original articles that assessed the use of antioxidants in exercise settings that compared antioxidants to a placebo were retrieved for review. 5

6 References Australian Institute of Sport. Antioxidant Vitamins C and E. Australian Institute of Sports Nutrition Department. Canberra, Australia. Viewed 9th August data/assets/ pdf_file/0004/478372/antioxidant_vitamins_12_-_website_fact_sheet.pdf Aguiló A, Tauler P, Fuentespina E, Villa G, Córdova A, Tur JA, Pons A. Antioxidant diet supplementation influences blood iron status in endurance athletes. Int J Sports Nut Ex Metab. 2004; 14: Basarici I, Altekin RE, Demir I, Yilmaz H. Urinary 8-isoprostane levels can indicate the presence, severity and extent of angiographic coronary artery disease. Acta Cerdiol. 2008;63: Bjelakovic G, Nikolova D, Gluud LL, et al. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis. JAMA 2007;297: Chan DW, Liu VW, Tsao GS, et al. Loss of MKP3 mediated by oxidative stress enhances tumorigenicity and chemoresistance of ovarian cancer cells. Carcinogenesis. 2008;29: Funes L, Carrera-Quintanar L, Cerdán-Calero M, Ferrer MD, Drobnic F, Pons A, Roche E, Micol V. Effect of supplementation on muscular damage markers, proinflammatory cytokines release and neutrophils oxidative stress in chronic exercise. Eur J Appl Physiol. 2011;111: Gomez-Cabrera MC, Domenech E, Romagnoli M, et al. Oral administration of vitamin C decreases muscle mitochondrial biogenesis and hampers training-induced adaptations in endurance performance. Am J Clin Nutr. 2008;87: Lee IM, Hsieh CC, Paffenbarger RSJ. Exercise intensity and longevity in men. The Harvard Alumni Health Study. JAMA. 1995;273: McGinley C, Shafat A, Donnelly AE. Does antioxidant vitamin supplementation protect against muscle damage? Sports Med. 2009; 39(12): Newsholme P, Krause M, Newsholme EA, et al. BJSM reviews: A-Z of nutritional supplements: dietary supplements, sports nutrition foods and Ergogenic aids for health and performance Part 18. Br J Sports Med. 2011; 45: Nieman DC, Laupheimer MW, Ranchordas MK, Burke LM, Stear SJ, Castell LM. BJSM reviews: A-Z of nutritional supplements: dietary supplements, sports nutrition foods and Ergogenic aids for health and performance Part 33. Br J Sports Med. 2012; 46: Nikolaidis M, Jamurtas A, Paschalis V, et al. The effect of muscle damaging exercise on blood and skeletal muscle oxidative stress. Sports Med. 2008; 38(7): Peternelj TT, Coombes JS. Antioxidant supplementation during exercise training: Beneficial or detrimental? Sports Med. 2011;41(12): Powers SK, Jackson MJ. Exercise-induced oxidative stress: cellular mechanisms and impact on muscle force production. Physiol Rev. 2008;88: Quindry JC. McAnulty SR, Hudson MB, Hosick P, Dumke C, McAnulty LS, Henson D, Morrow JD, Nieman D. Oral Quercetin supplementation and blood oxidative capacity in response to ultramarathon competition. Int J Sports Nut E Metab. 2008; 18: Quinn TJ, Sprague HA, Van Huss WD, Olson HW. Caloric expenditure, life status, and disease in former male athletes and non-athletes. Med Sci Sports Exerc. 1990;22: Paffenbarger RSJ, Hyde RT, Wing AL, Hsieh CC. Physical activity, all-cause mortality, and longevity of college alumni. N Engl J Med. 1986;314: Powers SK, Jackson MJ. Exercise-induced oxidative stress: Cellular mechanisms and impact on muscle force production. Physiol Rev. 2008; 88:

7 Ristow M, Zarse K, Oberbach A, et al. Antioxidants prevent health-promoting effects of physical exercise in humans. Proc Natl Acad Sci USA. 2009; 106: Sen CK. Antioxidants in exercise nutrition. Sports Med. 2001; 31(13): Shaper AG, Wannamethee G, Weatherall R. Physical activity and ischaemic heart disease in middle aged British men. Br Heart J. 1991;66: Skarpanska-Stejnborn A, Pilaczynska-Szczesniak L, Basta P, Deskur-Smielecka E. The influence of supplementation with Rhodiola rosea L. Extract on selected redox parameters in professional rowers. Int J Sports Nut Ex Metab. 2009; 19: Skarpanska-Stejnborn A, Pilaczynska-Szczesniak L, Basta P, Deskur-Smielecka E, Woitas-Slubowska D, Adach Z. Effects of oral supplementation with plant Superoxide Extract on selected redox and an inflammatory marker in a 2,000m rowing-ergometer test. Int J Sports Nut Ex Metab. 2011; 21: Stear SJ, Burke LM, Xastell LM. BJSM reviews: A-Z of nutritional supplements: dietary supplements, sports nutrition foods and Ergogenic aids for health and performance Part 3. Br J Sports Med. 2009; 43: Subudhi AW, Jacobs KA, Hagobian TA, Fattor JA, Muza SR, Fulco CS, Cymerman A, Friedlander AL. Changes in ventilatory threshold at high altitude: effect of antioxidants. Med Sci Sports Ex. 2006; 38(8): Williams SL, Strobel NA, Lexis LA, Coombes JS. Antioxidant requirements of endurance athletes: Implications for health. Nutrition Reviews. 2006; 6(3):

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