Nonetheless, large population studies with solid data both on the participants’ diets and causes of disease and death bolstered the beliefs that eating fish often was a heart-healthy practice linked to reduced rates of cardiovascular disease. For example, a comprehensive analysis conducted by Dr. Dariush Mozaffarian and Eric Rimm of the Harvard T.H. Chan School of Public Health found that eating two servings of fatty fish a week — equal to about two grams of omega-3 fatty acids — lowered the risk of death from heart disease by more than a third and total deaths by 17 percent.
16. Saito Y, Yokoyama M, Origasa H, Matsuzaki M, Matsuzawa Y, Ishikawa Y, Oikawa S, Sasaki J, Hishida H, Itakura H, et al. Effects of EPA on coronary artery disease in hypercholesterolemic patients with multiple risk factors: sub-analysis of primary prevention cases from the Japan EPA Lipid Intervention Study (JELIS). Atherosclerosis. 2008;200:135–40. [PubMed]
The American Heart Association (AHA) has made recommendations for EPA and DHA due to their cardiovascular benefits: individuals with no history of coronary heart disease or myocardial infarction should consume oily fish two times per week; and "Treatment is reasonable" for those having been diagnosed with coronary heart disease. For the latter the AHA does not recommend a specific amount of EPA + DHA, although it notes that most trials were at or close to 1000 mg/day. The benefit appears to be on the order of a 9% decrease in relative risk.[106] The European Food Safety Authority (EFSA) approved a claim "EPA and DHA contributes to the normal function of the heart" for products that contain at least 250 mg EPA + DHA. The report did not address the issue of people with pre-existing heart disease. The World Health Organization recommends regular fish consumption (1-2 servings per week, equivalent to 200 to 500 mg/day EPA + DHA) as protective against coronary heart disease and ischaemic stroke.
Omega-3 fatty acids have been shown to increase platelet responsiveness to subtherapeutic anticoagulation therapies, including aspirin. Recently, it was noted that patient response to aspirin for anticoagulation therapy is widely variable (45), and, thus, the number of patients with a low response to aspirin or aspirin resistance is estimated to range from <1% to 45%, depending on many variables. However, in patients with stable coronary artery disease taking low-dose aspirin, EPA+DHA supplementation has been proven to be as effective as aspirin dose escalation to 325 mg/d for anticoagulation benefits (45). The antiplatelet drug clopidogrel has also been associated with hyporesponsiveness in some patients. This could be attributed to poor patient compliance, differences in genes and platelet reactivity, variability of drug metabolism, and drug interactions. More importantly, in 1 study, patients receiving standard dual antiplatelet therapy (aspirin 75 mg/d and clopidogrel 600-mg loading dose followed by 75 mg/d) were assigned to either EPA+DHA supplementation or placebo. After 1 mo of treatment, the P2Y12 receptor reactivity index (an indicator of clopidogrel resistance) was significantly lower, by 22%, for patients taking EPA+DHA compared with patients taking placebo (P = 0.020) (46).
Several large trials have evaluated the effect of fish or fish oils on heart disease. In the Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto Miocardio (known as the GISSI Prevention Trial), heart attack survivors who took a 1-gram capsule of omega-3 fats every day for three years were less likely to have a repeat heart attack, stroke, or die of sudden death than those who took a placebo. (2) Notably, the risk of sudden cardiac death was reduced by about 50 percent. In the more recent Japan EPA Lipid Intervention Study (JELIS), participants who took EPA plus a cholesterol-lowering statin were less likely to have a major coronary event (sudden cardiac death, fatal or nonfatal heart attack, unstable angina, or a procedure to open or bypass a narrowed or blocked coronary artery) than those who took a statin alone. (3)
An animal study involving the omega-3 ETA discovered that subjects experienced a drop in overall inflammation similar to that caused by NSAIDs (non-steroidal anti-inflammatory drugs), but without the dangerous gastrointestinal side effects. The study authors also pointed out that eicosapentaenoic acid seems to be even more potent than the conventional omega-3s found in fish oil supplements (EPA/DHA). (56)
Before getting to know some of the fish oil side effects, you have to know more about fish oil, like its benefits and usages. Fish oil has become a popular supplement for athletes, as well as those looking to improve their overall health. Many claims have been made regarding the improvements to the body which can be made by using fish oil to increase the body's level of fatty omega-3 acids. Some of these claims have been backed up by studies, while others have not been proven with significant scientific evidence. There are also some precautions that need to be addressed if you will be taking fish oil regularly. People with certain health conditions may see a worsening of their symptoms if they increase their intake of fatty acids too quickly or with the wrong products.
So back to fish oil in general. The major fish oil benefits include decreasing the risk of heart disease and stroke while also helping reduce symptoms of depression, hypertension, attention deficit hyperactivity disorder (ADHD), joint pain, arthritis and chronic skin ailments like eczema. (2) Fish oil intake has also been associated with aiding the body in weight loss, fertility, pregnancy and increased energy. Prescription fish oil has even been approved by the FDA to lower unhealthy high triglyceride levels. (3)
Joensen, A. M., Schmidt, E. B., Dethlefsen, C., Johnsen, S. P., Tjonneland, A., Rasmussen, L. H., and Overvad, K. Dietary intake of total marine n-3 polyunsaturated fatty acids, eicosapentaenoic acid, docosahexaenoic acid and docosapentaenoic acid and the risk of acute coronary syndrome - a cohort study. Br J Nutr 2010;103(4):602-607. View abstract.

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An 18-month study was published in 2014 that evaluated how borage seed oil — rich in GLA — and fish oil rich fared against each other in treating patients with rheumatoid arthritis. It was discovered that all three groups (one taking fish oil, one taking borage oil and one taking a combination of the two) “exhibited significant reductions” in disease activity, and no therapy outperformed the others. For all three, “meaningful clinical responses” were the same after nine months. (11)
Another study conducted by researchers at Rhode Island Hospital examined the relationship between fish oil supplementation and indicators of cognitive decline. The subjects of the study were older adults: 229 cognitively normal individuals, 397 patients with mild cognitive impairment and 193 patients with Alzheimer’s disease. They were assessed with neuropsychological tests and brain magnetic resonance imaging every six months while taking fish oil supplements. The study found that the adults taking fish oil (who had not yet developed Alzheimer’s and did not have genetic risk factor for developing Alzheimer’s known as APOE ε4) experienced significantly less cognitive decline and brain shrinkage than adults not taking fish oil. (9)

Today, the average American has a 20:1 ratio of omega-6 to omega-3 fats, when a healthy ratio is more ideally around 2:1. Put in other numerical terms, the typical American diet tends to contain 14 to 25 times more omega-6 fatty acids than omega-3 fatty acids. (35) This shows just how deficient most of us are and why supplementing with fish oil is so beneficial.


The American Heart Association (AHA) recommends that everyone eats fish (particularly fatty, coldwater fish) at least twice a week. Salmon, mackerel, herring, sardines, lake trout, and tuna are especially high in omega-3 fatty acids. While foods are your best bet for getting omega-3s in your diet, fish oil supplements are also available for those who do not like fish. The heart-healthy benefits of regular doses of fish oil supplements are unclear, so talk to your doctor to see if they're right for you. If you have heart disease or high triglyceride levels, you may need even more omega-3 fatty acids. Ask your doctor if you should take higher doses of fish oil supplements to get the omega-3s you need.
Jump up ^ Siscovick DS, Barringer TA, Fretts AM, Wu JH, Lichtenstein AH, Costello RB, Kris-Etherton PM, Jacobson TA, Engler MB, Alger HM, Appel LJ, Mozaffarian D (2017). "Omega−3 Polyunsaturated Fatty Acid (Fish Oil) Supplementation and the Prevention of Clinical Cardiovascular Disease: A Science Advisory From the American Heart Association". Circulation. 135 (15): e867–84. doi:10.1161/CIR.0000000000000482. PMID 28289069.
Haberka, M., Mizia-Stec, K., Mizia, M., Janowska, J., Gieszczyk, K., Chmiel, A., Zahorska-Markiewicz, B., and Gasior, Z. N-3 polyunsaturated fatty acids early supplementation improves ultrasound indices of endothelial function, but not through NO inhibitors in patients with acute myocardial infarction: N-3 PUFA supplementation in acute myocardial infarction. Clin.Nutr. 2011;30(1):79-85. View abstract.

Gorjao, R., Verlengia, R., Lima, T. M., Soriano, F. G., Boaventura, M. F., Kanunfre, C. C., Peres, C. M., Sampaio, S. C., Otton, R., Folador, A., Martins, E. F., Curi, T. C., Portiolli, E. P., Newsholme, P., and Curi, R. Effect of docosahexaenoic acid-rich fish oil supplementation on human leukocyte function. Clin Nutr 2006;25(6):923-938. View abstract.


Preventing re-blockage of blood vessels after angioplasty, a procedure to open a closed blood vessel. Research suggests that fish oil decreases the rate of blood vessel re-blockage by up to 45% when given for at least 3 weeks before an angioplasty and continued for one month thereafter. But, when given for 2 weeks or less before angioplasty, it doesn't seem to have any effect.
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