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  • Fish Oil Technical Document November 2013

    Fish Oils

    Technical Document Developed by INDI/SNIG for the Irish Sports Council 2013

  • Fish Oil Technical Document November 2013

    Fish Oil Pubmed (Medline), SPORTDiscus and the Cochrane Library were searched for all human studies published in peer reviewed journals in the last 5 years. The terms: fish oils, fish oils AND exercise and fish AND exercise were used as key terms in all databases. Inclusion criteria

    Human studies published in English

    Original investigations assessing the use of fish oils and exercise

    Incorporated the use of an indistinguishable placebo Exclusion Criteria

    Studies assessing fish consumption

    Studies assessing the effect of fish consumption in diseased populations

    Qualitative studies assessing supplement use in both the general and athletic population

    After title and abstract review, seven original articles that assessed the use of fish oils and exercise were retrieved for review. Introduction Fish oils are made up of the long chained omega-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA are synthesized from -linolenic acid and are found in the tissue of oily fish such as mackerel, sardines, herring, salmon, trout, tuna and mullet (Ruxton et al. 2004). Over time the consumption of omega-3 and omega-6 fatty acids by humans has changed substantially. Sources of omega-6 fatty acids include polyunsaturated oils - sunflower, safflower, soybean, corn and grape-seed oil, polyunsaturated margarines, nuts - brazil, walnuts, and seeds sunflower and safflower. Humans, thousands of years ago, probably consumed omega-3 to omega-6 fatty acids in a ratio of 1:1 to 1:2. Today, humans consume approximately 20-25 times more omega-6 fatty acids compared to omega-3 fatty acids. This dramatic increase in omega-6 fatty acids, from studies, is associated with an increase of proinflammatory markers (leukotrienes and prostanoids) which can cause an increase in blood thickness, blood vessel spasm, and blood vessel constriction, and decreases in bleeding time in humans (Mickleborough and Rundell 2005, Simopoulos 2007).

  • Fish Oil Technical Document November 2013

    Omega-3 fatty acids possess anti-inflammatory properties along with antithrombotic, antiarrhythmic, hypolipidaemic, and vasodilatory properties (Ruxton et al. 2004). The anti-inflammatory effects appear to have a direct action on immune function through neutrophil and monocyte production of mediators, chemotactic responses, and the production of cytokines (Helenius et al. 2005).

    The health benefits of consuming oily fish or fish oil supplements There is a substantial amount of scientific literature demonstrating the cardiovascular benefits of regular consumption of oily fish or fish oil supplements, and their constituent omega-3 PUFA. Interest in the cardio-protective effects of consuming omega-3 fatty acids has focused around decreasing triglycerides (Harris et al. 1988, Harris et al 1997, Conner 2000, Thomas et al. 2007, Waite et al. 2008, Sadovsky et al. 2009), decreasing low density lipoprotein cholesterol (Sadovsky et al. 2009, Barter and Ginsberg 2008), decreasing blood pressure (Waite et al. 2008, Morris et al. 1993, Mori 2006), increasing high density lipoprotein cholesterol (Thomas et al. 2007); decreasing resting heart rate (Mozaffarian et al. 2005, OKeefe et al. 2006) and improving blood flow (Khan et al. 2003, Walser et al. 2006, Walser et al. 2008). The consumption of omega-3 fatty acids has also demonstrated positive outcomes for the secondary prevention of cardiovascular disease. The GISSI study (1999), the largest study involving over 11 000 subjects who had suffered acute myocardial infarction, demonstrated that subjects ingesting omega-3 PUFA supplements had a significant reduction in cardiac events over the 3.5 years in which they were observed (GISSI 1999). Apart from cardiovascular disease, favourable effects on other health conditions, such as decreasing the risk of psychiatric disorders (Jacka et al. 2004, Peet and Stokes 2005), increasing insulin sensitivity (Waite et al. 2008), decreasing the risk of metabolic syndrome (Watts et al. 2006), improving brain development (Uauy and Dangour 2006) and decreasing chronic pain in joints and the spine (Cleland et al. 2003) have been reported. A comprehensive review of the health effects of omega-3 fatty acid consumption has been published by Ruxton et al. (2004). There is emerging evidence that the consumption of oily fish or fish oil supplements can aid in the treatment of some inflammatory conditions such as rheumatoid arthritis, Crohns disease, ulcerative colitis, psoriasis, asthma, lupus and cystic fibrosis (Ruxton et al. 2004, Mickleborough et al. 2005, Cleland et al. 2009). However, to-date the scientific evidence for these inflammatory diseases is not conclusive and more research is required before conclusions can be drawn.

  • Fish Oil Technical Document November 2013

    The athletic benefits of consuming oily fish or fish oil supplements Studies on athletic populations have demonstrated some cardiovascular benefits including: improved stroke volume and cardiac output (Walser et al. 2008), increased rate of fat oxidation while exercising (Huffman et al. 2004), and decreased heart rate during exercise (Peoples et al. 2008, Ninio et al. 2008). A recent study found no effect of an acute DHA or EPA enriched meal on cardiac output or stroke volume during exercise (Rantoyanni et al. 2012). Rantoyanni et als (2012) study indicated a DHA enriched meal promoted greater vasodilation during exercise compared to an EPA meal. Cardiopulmonary benefits, pulmonary function tests (Tartibian et al. 2010) and reduced symptoms of exercise-induced bronchoconstriction (Mickleborough et al. 2005, Mickleborough et al. 2006), have been documented in the literature. There is no conclusive evidence that consuming fish oils will enhance athletic performance. One study has indicated improved complex reaction time and efficiency time after 12 weeks of omega-3 fatty acid supplements (Guzman et al. 2011). In contrast, other studies have found no change in energy metabolism (Bortolotti et al. 2007), no effect on endurance performance (Oostenbrug et al. 1997), and no performance benefits (Raastad et al. 1997, Buckley et al. 2009) after omega-3 fatty acid supplementation. A summary of these studies can be seen in Table 1. Fish Oil consumption and muscle atrophy There is new evidence, although rather limited, to suggest that fish oil supplementation can help reduce muscle atrophy. A study, carried out by Smith and colleagues (2011), found that fish oil -derived omega 3 fatty acid supplementation stimulated muscle protein synthesis in older adults. Interestingly, recent animal studies have demonstrated that dietary supplementation of fish oils may alleviate muscle loss during immobilization (You et al. 2010, Yulan et al. 2013). These intriguing results propose relevant application of fish oil supplements in immobilised injured athletes; however, more studies using human populations are warranted for this to be more plausible. Safety concerns with fish oil consumption Fish oil supplementation does not appear to induce any clinically significant side effects, with the majority of research not reporting any adverse effects at all. Some adverse effects from consuming fish oil supplements may include a fishy aftertaste, gastrointestinal disturbances, and nausea (Kris-Etherton et al, 2002, Peet et al. 2006). Other side effects may include excessive bleeding in some individuals when fish oils supplementation is greater than 3 g of EPA and DHA (Kris-Etherton et al. 2002). Though Fish oil has not been implicated in serious adverse drug interactions, individuals with pre-existing haemorrhagic disorders

  • Fish Oil Technical Document November 2013

    or those on anticoagulant treatment should seek medical advice before supplementation (Peet et al. 2006, Cleland et al. 2009). It has been deemed by the American Food and Drug Administration that fish oil supplementation up to 3g per day is generally recognised as safe for inclusion in the human diet (Kris-Etherton et al. 2002). Conclusion It is clear that omega-3 fatty acids can play an important role in the general health of the human population. These omega-3 fatty acids can be obtained from consuming oily fish, or as fish oil supplements. Though there has yet to be any research identifying a direct impact of fish oil consumption on athletic performance, indirect markers such as increases in blood flow, increased stroke volume and cardiac output, and possible increased fat oxidation during exercise are positive starting points for future research into fish oil supplementation and exercise performance. It can therefore be recommended that oily fish or fish oils be consumed for cardiovascular benefits, but not as a means for directly enhancing athletic performance.

  • Fish Oil Technical Document November 2013

    Reference Subjects Dose Exercise Protocol Performance Enhancement


    Oostenbrug et al. 1997

    24 well trained male cyclists

    3 weeks of FO supplementation

    (6 g/day), without or with

    vitamin E (300 IU/day)

    Wmax (peak power output) and endurance cycling tests completed before and after supplementation. Time to complete the endurance exercise test was the primary outcome measure and was completed at 70% of the pre-determined peak power output from the Wmax.

    No FO did not improve endurance performance, change antioxidant levels or LDL oxidation during exercise.