The aim of this article is to give a brief review on fish oil supplementation to inform on current research whilst providing practical applications to readers.

I’ll then look to summarise my findings and give my personal opinion in a brief conclusion at the end, so if you’re looking for a more digestible read then I’d suggest scanning straight to the end of the article.

Before reviewing current literature it is important to understand what exactly fish oil is. Essentially fish oil is made up of two fatty acids EPA (Eicosapentaenoic Acid) and DHA (Docosahexaenoic acid), and is a form of polyunsaturated fat derived primarily from oily fish in the human diet.

Touted as having benefits for reducing plasma triglycerides, blood pressure, inflammation, increasing cognitive function and development amongst a host of other benefits, does the research stand up to these claims?

Triglycerides

Plasma triglycerides circulate in the blood and high levels are seen as a risk factor for cardiovascular diseases with normal triglyceride levels below 150mg/dl.

Research is quite conclusive, finding that low doses of fish oil reduce serum triglycerides significantly (Cazzola et al., 2007; Oelrich, Dewell & Gardner, 2011; Skulas-Ray et al., 2011). Although dosing is often contradictory with low and high dosing seemingly preferable in similar studies.

Cholesterol

There appears to be no significant relationship between fish oil supplementation and change in total cholesterol (Ciubotaru, Lee & Wander, 2003; Eslick et al., 2009; Poppitt et al., 2009).

Cardiovascular Disease (CVD)

Research appears fairly conclusive that omega 3 consumption is associated with a lowered risk of mortality from CVD (Kris-Etherton, Harris & Appel, 2003; Wang et al., 2006).

Inflammation

Inflammation is at the heart of many chronic diseases and therefore reducing chronic inflammation will go some way to improving the health of many individuals both previously diagnosed and those at risk of future diagnosis.

Although a few studies have identified the potential for mediation of inflammatory markers through greater consumption of omega 3 (Wall et al., 2010), it seems the body of literature doesn’t support the publicity fish oil gets as an anti-inflammatory agent, with many studies reporting no effect on inflammatory markers (Pot et al., 2009; Vega-López et al., 2004).

Blood Pressure

It appears that hypertensive individuals may experience significant lowering of blood pressure when consuming fish oil supplementation (Cambell et al., 2013), however the effects are modest and should certainly not replace other interventions.

Depression

It appears that omega 3 supplementation may have significant positive effects in severely depressed populations (Sarris, Mischoulon  & Schweitzer, 2012), with EPA having the greatest effect and DHA seeing no significant effect (Marangell et al.,  2003; Martins, 2009).

Although symptoms appear to be significantly but not hugely reduced in severely depressed populations, mildly depressed individuals appear to experience no significant effects. Perinatal depression also appears unaffected (Mozurkewich et al., 2013).

All-Cause Mortality

Several epidemiological studies have suggested a relationship between fish consumption and all-cause mortality (Dolecek, 1992; Zhang et al., 1999), however only correlation data is presented and it doesn’t provide conclusive evidence on causation. The true mechanism is largely unknown and is likely a result of a multitude of confounding variables.

Current all-cause mortality data focusses on overall omega 3 intake and not solely fish oil consumption.

Weight Loss

Although suggestions are made to the effects of fish oil consumption when weight loss is a primary goal, the data doesn’t support this hypothesis (Bays et al., 2009).

Conclusion

In most populations I believe an increase in omega 3 consumption will provide some protective mechanisms as well as improvements in cognitive function and general wellbeing.

Although providing a host of benefits to human health and performance, the overall positive effects of omega 3 are largely overstated by manufacturers of supplements and media alike.

For the most part supplementation with fish oil will be a secondary alternative for most, with whole food sources certainly being preferable.

However with the availability of well sourced fish high in omega 3 fatty acids limited in some cases due to fish farming and the risk of trace metals with certain methods, the argument for supplementation may become more prominent. Not to mention that with the ever growing cost of high quality fish, many are put off through that alone before even considering sourcing and availability.

It appears when considering supplementation EPA content has a greater effect than DHA on most parameters, with a ratio of 6:4 seemingly preferable and should be considered when purchasing supplementation.

Due to confounding variables whole food consumption will be preferable not only from an omega 3 standpoint, but also because in most cases populations will subsequently lower processed red meat consumption and potentially overall calorie intake during omega 3 rich meals. Giving another positive suggestion for practitioners to increase fish consumption in individuals looking to move towards optimal health and performance.

Jack Barton (Researcher, Rescon Ltd)

References

Bays, H. E., Maki, K. C., Doyle, R. T., and Stein, E. (2009). ‘The effect of prescription omega-3 fatty acids on body weight after 8 to 16 weeks of treatment for very high triglyceride levels.’ Postgraduate Medicine, 121(5), 145.

Campbell, F., Dickinson, H. O., Critchley, J. A., Ford, G. A., and Bradburn, M. (2013). ‘A systematic review of fish-oil supplements for the prevention and treatment of hypertension.’ European Journal of Preventive Cardiology, 20(1), 107-120.

Cazzola, R., Russo-Volpe, S., Miles, E. A., Rees, D., Banerjee, T., Roynette, C. E.,  and Cestaro, B. (2007). ‘Age-and dose-dependent effects of an eicosapentaenoic acid-rich oil on cardiovascular risk factors in healthy male subjects.’ Atherosclerosis, 193(1), 159-167.

Ciubotaru, I., Lee, Y. S., and Wander, R. C. (2003). Dietary fish oil decreases C-reactive protein, interleukin-6, and triacylglycerol to HDL-cholesterol ratio in postmenopausal women on HRT. The Journal of Nutritional Biochemistry, 14(9), 513-521.

Dolecek, T. A. (1992). ‘Epidemiological evidence of relationships between dietary polyunsaturated fatty acids and mortality in the multiple risk factor intervention trial.’ In Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, NY). 200(2), 177-182

Eslick, G. D., Howe, P. R., Smith, C., Priest, R., and Bensoussan, A. (2009). ‘Benefits of fish oil supplementation in hyperlipidemia: a systematic review and meta-analysis.’ International Journal of Cardiology, 136(1), 4-16.

Kris-Etherton, P. M., Harris, W. S., and Appel, L. J. (2003). ‘Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease.’ Arteriosclerosis, Thrombosis, and Vascular biology, 23(2), e20-e30.

Marangell, L. B., Martinez, J. M., Zboyan, H. A., Kertz, B., Kim, H. F. S., et al.(2003). A double-blind, placebo-controlled study of the omega-3 fatty acid docosahexaenoic acid in the treatment of major depression. American Journal of Psychiatry, 160(5), 996-998.

Martins, J. G. (2009). ‘EPA but not DHA appears to be responsible for the efficacy of omega-3 long chain polyunsaturated fatty acid supplementation in depression: evidence from a meta-analysis of randomized controlled trials.’ Journal of the American College of Nutrition, 28(5), 525-542.

Mozurkewich, E. L., Clinton, C. M., Chilimigras, J. L., Hamilton, S. E., Allbaugh, L. J., et al. (2013). The Mothers, Omega-3, and Mental Health Study: a double-blind, randomized controlled trial. American Journal of Obstetrics and Gynecology, 208(4), 313-e1.

Oelrich, B., Dewell, A., and Gardner, C. D. (2011). ‘Effect of fish oil supplementation on serum triglycerides, LDL cholesterol and LDL subfractions in hypertriglyceridemic adults.’ Nutrition, Metabolism and Cardiovascular Diseases.

Poppitt, S. D., Howe, C. A., Lithander, F. E., Silvers, K. M., Lin, R. B., et al. (2009). ‘Effects of Moderate-Dose Omega-3 Fish Oil on Cardiovascular Risk Factors and Mood After Ischemic Stroke A Randomized, Controlled Trial.’ Stroke, 40(11), 3485-3492.

Pot, G. K., Brouwer, I. A., Enneman, A., Rijkers, G. T., Kampman, E., et al. (2009). No effect of fish oil supplementation on serum inflammatory markers and their interrelationships: a randomized controlled trial in healthy, middle-aged individuals. European Journal of Clinical Nutrition, 63(11), 1353-1359.

Sarris, J., Mischoulon, D., & Schweitzer, I. (2012). ‘Omega-3 for bipolar disorder: meta-analyses of use in mania and bipolar depression.’ The Journal of Clinical Psychiatry, 73(1), 81-86.

Skulas-Ray, A. C., Kris-Etherton, P. M., Harris, W. S., Heuvel, J. P. V., Wagner, P. R., et al.(2011). Dose-response effects of omega-3 fatty acids on triglycerides, inflammation, and endothelial function in healthy persons with moderate hypertriglyceridemia. The American Journal of Clinical Nutrition, 93(2), 243-252.

Vega-López, S., Kaul, N., Devaraj, S., Cai, R. Y., German, B., et al. (2004). Supplementation with ω3 polyunsaturated fatty acids and all-rac alpha-tocopherol alone and in combination failed to exert an anti-inflammatory effect in human volunteers. Metabolism, 53(2), 236-240

Wall, R., Ross, R. P., Fitzgerald, G. F., and Stanton, C. (2010). Fatty acids from fish: the anti‐inflammatory potential of long‐chain omega‐3 fatty acids. Nutrition reviews, 68(5), 280-289.

Wang, C., Harris, W. S., Chung, M., Lichtenstein, A. H., Balk, E. M., et al. (2006). ‘n− 3 Fatty acids from fish or fish-oil supplements, but not α-linolenic acid, benefit cardiovascular disease outcomes in primary-and secondary-prevention studies: a systematic review.’ The American Journal of Clinical Nutrition, 84(1), 5-17.

Zhang, J., Sasaki, S., Amano, K., and Kesteloot, H. (1999). ‘Fish consumption and mortality from all causes, ischemic heart disease, and stroke: an ecological study.’ Preventiv