Does fish oil and EPA supplementation provide cardioprotection?

Does fish oil and EPA supplementation provide cardioprotection?

The drive towards healthy aging has prompted people in incorporating fish/fish oil supplements in their diet due to its richness in omega-3 fatty acids, which is touted to have several health benefits related to depression, stroke, diabetes mellitus, cancer and Alzheimer’s disease1.

The interest of researchers grew in fish and fish oil, after a study by Bang and colleagues2 that suggested the decreased incidence of ischemic heart disease in Greenland Eskimos due to higher dietary intake of fish (rich in polyunsaturated fatty acids such as eicosapentaenoic and docosahexaenoic acids) than Danes. Since then several studies suggest a possible association between fish/fish oil intake and cardiovascular diseases prevention. In fact, in view of the rising evidence, WHO and many countries recommend dietary supplementation of omega-3 fatty acids in the form of fish or fish oil supplements3.

Marine-derived omega-3 fatty acids, such as EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are anti-inflammatory precursors. The potential mechanisms of omega-3 fatty acids in cardioprotection include anti-inflammation, vasodilation and improved endothelial function, stabilization of atherosclerotic plaque, hypotriglyceridemia, anti-thrombosis, anti-arrhythmia, cardiac remodeling, and improved exercise tolerance and cognitive function4. Conversely, arachidonic acid (an omega-6 fatty acid) is principally considered proinflammatory4,5.

EPA competes with AA (arachidonic acid) for cyclooxygenase and lipoxygenase enzymes, thus reducing the inflammatory effect of AA by reduced production of its highly inflammatory eicosanoids6. Therefore, the ratio of EPA to AA can be considered a measurement of chronic inflammation; the higher the ratio, the lower is the inflammation and vice versa5.

A study performed on 88 obese Japanese patients with dyslipidemia showed a positive correlation of treatment with highly purified EPA (1.8 g/day) for 3 months. The result showed an increased in EPA:AA ratio and vascular function along with a decrease in arterial stiffness and inflammation. This study highlights the cardioprotective role of EPA by statistically significant reduction in metabolic variables, such as A1C levels, total cholesterol, triglycerides, C-reactive protein and cardio-ankle vascular index (a marker for arterial stiffness), and elevation of EPA:AA ratio and adiponectin levels7.

Higher EPA:AA ratio has been associated with decreased prevalence of coronary artery disease; however, this cannot be said for DHA:AA ratio8. The Hisayama study9 is one such prospective study executed in a total of 3103 Japanese people ≥40 years of age followed through for an average of 5.1 years. In individuals with HS-CRP (high-sensitivity C-reactive protein) ≥1.0 mg/l, with every 0.20 decrement in the serum EPA:AA ratio, the risk of cardiovascular disease and coronary artery disease increased by 1.52 and 2.23 times, respectively. However, no significant association was noted for DHA:AA ratio.

Apart from coronary artery disease, EPA:AA ratio has also been associated with acute coronary syndrome, myocardial infarction, stroke, chronic heart failure, and peripheral artery and vascular disease10-14. These studies emphasize the role of EPA not only in coronary artery disease, but in overall cardioprotection.

However, there are other studies that failed to see any beneficial effect of omega-3 fatty acids in cardiovascular disease, neither in primary nor secondary prevention15,16.

Although, there have been conflicting evidence regarding the role of omega-3 fatty acid in cardioprotection, consumption of a healthy diet with serving of fatty fish (200-400 g) every week is still recommended. In individuals with insufficient intake of fish, fish oil supplements in the form of EPA and DHA (0.3-1.0g/d) is recommended3,4. Therefore, fish/fish oil supplement is not only implicated in cardioprotection, but also for health conscious individuals to reap its benefits for healthy aging.


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