Fish oil supplementation has been shown to decrease blood triglyceride levels in both athletes and nonathletes. Its role in the prevention of cardiovascular disease has been fairly well established; however, fish oil supplementation has not been shown to be an effective ergogenic aid in exercise performance. Longer term studies may be needed to evaluate if fish oil supplementation has a benefit on endurance performance, and larger sample sizes also are needed.
BACKGROUND ON FISH OILS
Fish oils originate from the tissues of oily fish and contain high levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), both forms of omega-3 fatty acids (3). These omega-3 fatty acids are converted into signaling molecules called eicosanoids, which have been shown to decrease inflammation within the body (3). Fish do not produce EPA and DHA, instead these omega-3 fatty acids accumulate in the fish based on their dietary intake.
Fish high in omega-3 fatty acids are sharks, swordfish, tilefish, and albacore tuna; however, because these fish also may accumulate toxic substances, the United States Food and Drug Administration recommends that we limit consumption of these fish to avoid high levels of mercury, dioxin, polychlorinated biphenyls, and chlordane (2). The Table lists various types of fish and the amount of omega-3 fatty acids provided (7).
Why is fish oil considered so important to health? Some researchers have reported that omega-3 fatty acids, particularly those in fish oil, may help decrease blood pressure and/or high triglyceride levels in the blood and, thus, may help in preventing coronary heart disease (4). The evidence that fish oil can decrease blood triglyceride levels is strong. Fish oil also may help prevent heart disease and stroke; however, overconsumption of fish oil can increase the risk of stroke, thus, taking the recommended doses is important (4).
Some individuals take fish oil supplements to help with depression, psychosis, attention deficit-hyperactivity disorder, Alzheimer disease, and other disorders related to the brain. Fish consumption and fish oil supplementation, in particular, EPA and DHA, have been dubbed “brain food” because of the relationship between these omega-3 fatty acids and improvement in cognitive function (4). Fish oil supplementation, however, has not been definitively linked with improving the above conditions.
Although fish oil and consumption of fish have been linked to prevention of a number of disorders and diseases, it is important to read the scientific literature to ascertain what benefits have been found and what benefits are anecdotal. Certainly, increasing fish consumption has its benefits; however, it is not a panacea for the number of diseases and disorders that may be advertised.
FISH OIL SUPPLEMENTATION AND ATHLETIC PERFORMANCE
A number of studies have been conducted on different aspects of fish oil supplementation and athletic performance. Among 23 trained cyclists, Nieman et al. (5) researched the effects of 6 weeks of fish oil supplementation (2.4 g/day; 2,000 mg of EPA and 400 mg of DHA) on exercise performance, inflammation, and immune measures before and after 3 days of intense exercise. This was a randomized placebo-controlled trial, where 11 cyclists received the fish oil supplement and 12 cyclists received a placebo. Nieman et al. (5) reported that fish oil supplementation significantly increased blood levels of EPA and DHA but did not affect exercise performance, inflammation, or immune response. Thus, it does not appear that this short-term supplementation had a positive effect in the trained cyclists.
Poprzecki et al. (6) took a slightly different approach to studying fish oil supplementation and exercise. Their aim was to examine if endurance exercise would alter the blood antioxidant levels and blood lipid levels after 6 weeks of supplementation with 1.3 g of omega-3 fatty acids or a placebo in healthy active males. Poprzecki et al. (6) reported that blood triglyceride levels were decreased after 6 weeks of omega-3 fatty acid supplementation. Furthermore, they found that antioxidant activity, assessed by measuring specific enzyme activity, was increased after omega-3 fatty acid supplementation.
Can fish oil supplementation positively affect endurance performance, recovery, and/or cardiovascular disease risk factors in Australian Rules football players? Buckley et al. (1) studied this during a 5-week period. Their sample included 25 players who were randomly assigned to either 6 g/day of DHA-rich fish oil or a placebo (sunflower oil). They evaluated omega-3 fatty acids in blood, resting blood pressure, blood triglyceride levels, and heart rate. Buckley et al. (1) reported a significant increase in omega-3 fatty acids in the blood of the players who were supplementing with the fish oil. In addition, blood triglyceride levels, resting diastolic blood pressure, and heart rate during submaximal exercise were all significantly lower in the players who supplemented with the fish oil during the 5-week period compared with the placebo group. There were no differences in peak endurance performance or recovery between groups. It appears that fish oil supplementation may have positively affected cardiovascular risk factors but did not affect performance in these Australian Rules football players.
Fish oil supplementation has been shown to decrease blood triglyceride levels in both athletes and nonathletes. Its role in the prevention of cardiovascular disease has been fairly well established; however, fish oil supplementation has not been shown to be an effective ergogenic aid in exercise performance. Longer term studies may be needed to evaluate if fish oil supplementation has a benefit on endurance performance, and larger sample sizes also are needed. In addition, comparisons of the same amount of fish oil, with the same ratio of EPA to DHA, are required to more definitively assess if fish oil supplementation plays a role in athletic performance. For individuals who are not vegans or vegetarians, consumption of more fish in the diet will increase fish oil intake and provides an excellent source of protein. Consuming fish at the lower end of the food chain (e.g., sardines or anchovies) will reduce the risk of mercury contamination.
1. Buckley JD, Burgess S, Murphy KJ, Howe PR. DHA-rich fish oil lowers heart rate during submaximal exercise in elite Australian Rules footballers. J Sci Med Sport. 2009; 12 (4): 503–7.
2. EPA (2007-01-31). Fish consumption advisories [cited 2012 May 20]. Available from: http://www.epa.gov/mercury/advisories.htm2012
3. Moghadasian MH. Advances in dietary enrichment with n-3 fatty acids. Crit Rev Food Sci Nutr. 2008; 48 (5): 402–10.
4. National Institutes of Health. NIH Medline Plus. Fish oil [cited 2012 May 20]. Available from: http://www.nlm.nih.gov/medlineplus/druginfo/natural/993.html2012
5. Nieman DC, Henson DA, McAnulty SR, Jin F, Maxwell KR. N-3 polyunsaturated fatty acids do not alter immune and inflammation measures in endurance athletes. Int J Sport Nutr Exerc Metab. 2009; 19 (5): 536–46.
6. Poprzecki S, Zajac A, Chalimoniuk M, Waskiewicz Z, Langfort J. Modification of blood antioxidant status and lipid profile in response to high-intensity endurance exercise after low doses of omega-3 polyunsaturated fatty acids supplementation in healthy volunteers. Int J Food Sci Nutr. 2009; 60 (suppl 2): 67–79.
7. United States Department of Agriculture Nutrient Data Laboratory [cited 2012 May 22]. Available from: http://www.ars.usda.gov/main/site_main.htm?modecode=12-35-45-002012
Office of Dietary Supplements, National Institutes of Health. Available from: http://ods.od.nih.gov/health_information/omega_3_fatty_acids.aspx