Fish oil supplements and heart disease

‘Natural’ ways to reduce your heart attack and stroke risk include exercise and lifestyle. But what about natural supplements such as fish oil?

  • Eating oily fish 2 or 3 times a week as part of a healthy diet is recommended for cardiovascular health.
  • Increasingly, the research shows that fish oil supplements are unlikely to reduce the risk of heart attack or stroke in people who already have cardiovascular problems. There has been less research in people who don’t have heart disease, but the evidence of a benefit in these people is weak.
  • Fish oil (omega-3 fatty acid) supplements can reduce high levels of triglycerides (a type of fat).
  • If you choose to take fish oil, make sure you don’t use it as a substitute for your medicines that can help you reduce your cardiovascular risk.
  • Fish oil supplements don’t have many side effects, but at high doses they may interact with medicines that reduce blood clotting, such as warfarin and aspirin.

Include oily fish in your diet

Eating oily fish (rich in omega-3 fats) regularly may improve your cardiovascular health.

Populations with a high intake of oily fish have been found to have lower rates of heart disease than populations who don’t. For this reason most guidelines recommend 2 to 3 serves a week of oily fish (fresh or canned) as part of a healthy diet for preventing cardiovascular disease and for people who already have cardiovascular disease.

If you can’t meet these dietary recommendations then taking a fish oil (omega-3 fatty acid) supplement may be useful for you. Although be aware that people who eat lots of fish may have a healthier diet in other ways, and this may have contributed to their lower risk of heart disease in these studies.

See the Heart Foundation website for more information about fish and diet.

Heart attack and stroke benefits appear less likely as more research is done

Clinical trials of fish oil supplements, haven’t shown a clear benefit for preventing further cardiovascular disease in people who have already had a stroke or heart attack. Some earlier trials showed a benefit, but more recent trials haven’t — so the evidence to support their use is not as strong as it first appeared. Fewer trials have looked at prevention with supplements in people without any previous cardiovascular problems, but there has not been a clear benefit in this group either.

In clinical trials, one group of people takes fish oil supplements and the other doesn’t. This kind of research is considered a more reliable form of evidence than population studies. Read more about how trial results of fish oil supplements have changed over time.

Fish oil reduces high triglyceride levels

Fish oil supplements containing eicosapentanoic acid (EPA)/docosahexanoic acid (DHA) have been shown to reduce high triglyceride levels and are an option for people with this problem. You need to take doses of 2 to 5 g daily of total EPA/DHA to lower triglyceride levels in the blood. Triglycerides are one of the fats in your blood, but not everyone with high cholesterol has high triglycerides.

It’s thought that reducing triglycerides could reduce risk of a heart attack or stroke, but your overall risk depends on other risk factors. You need a blood test to tell you if you have high triglyceride levels.

Fish oil doesn’t replace other treatments

While you might choose to take fish oil supplements in addition to other treatments, fish oil is not a substitute for other medicines for cardiovascular disease, such as aspirin, blood pressure medicines and cholesterol-lowering medicines. These other medicines have very strong evidence from clinical trials that they work, while expert opinions are mixed about whether fish oil supplements reduce the risk of cardiovascular events — especially for people who already have cardiovascular disease. A healthy lifestyle, including exercise and healthy eating are also vital.

If you are deciding about fish oil supplements, think about what is important to you and talk to your doctor. Your dietary intake of fish, how many medicines you already take, your personal preferences, and costs are all factors to consider when working out if fish oil supplements are a good choice for you.

You can also call NPS Medicines Line on 1300 MEDICINE (1300 633 424) to get information about fish oil supplements and any other medicines, from anywhere in Australia, Monday to Friday, 9am to 5pm AEST.

Read our cholesterol pages for more information about understanding your cardiovascular risk, cholesterol, and statins.

High doses may affect blood clotting

Fish oil supplements do not have many side effects and at doses less than 2 g daily of EPA/DHA, serious side effects are rare.

If you take more than 2 g daily of EPA/DHA your blood might take longer to clot. If you are taking other medicines that thin the blood, such as warfarin or aspirin, this could cause you bleeding problems, such as stomach or bowel bleeding.

Always tell your doctor about all the medicines you are taking, including supplements and complementary medicines, such as herbal remedies, to avoid interactions with any of your medicines.

Find more about using complementary medicines and how to be medicinewise.

Know your oils

  • Omega 3 PUFAs — Polyunsaturated fatty acids containing omega-3. Omega-3 PUFAs are available from plant, animal and marine sources. See the National Heart Foundation for more information
  • DHA — Docosahexanoic acid, a type of omega-3 in fish and other marine animals
  • EPA — Eicosapentanoic acid, a type of omega-3 in fish and other marine animals
  • Krill oil — another source of DHA and EPA. No large trials have compared the cardiovascular effects of krill oil with fish oil.
  • National Heart Foundation of Australia. Position statement: Fish, fish oils, n-3 polyunsaturated fatty acids and cardiovascular health, updated November 2008. (accessed 9 August 2010).
  • Rossi S, ed. Australian Medicines Handbook. Adelaide, 2011.
  • Cardiovascular Writing Group. Fish oil (omega-3 long chain polyunsaturated fatty acids), revised October 2010, etg33 March 2011:Therapeutic Guidelines Ltd. (accessed 22 July 2011).
  • Cardiovascular Writing Group. Therapeutic Guidelines: Cardiovascular. Version 5 ed. Melbourne: Therapeutic Guidelines Ltd, 2008.
  • Kromhout D, Giltay EJ, Geleijnse JM. n-3 Fatty Acids and Cardiovascular Events after Myocardial Infarction. N Engl J Med 2010;363:2015–26.
  • Galan P, Kesse-Guyot E, Czernichow S, et al. Effects of B vitamins and omega 3 fatty acids on cardiovascular diseases: a randomised placebo controlled trial. BMJ 2010;341:c6273.
  • Rauch B, Schiele R, Schneider S, et al. OMEGA, a randomized, placebo-controlled trial to test the effect of highly purified omega-3 fatty acids on top of modern guideline-adjusted therapy after myocardial infarction. Circulation 2010;122:2152–9.
  • Rizos EC, Ntzani EE, Bika E, et al. Association between omega-3 fatty acid supplementation and risk of major cardiovascular disease events. A systematic review and meta-analysis. A systematic review and meta-analysis. JAMA 2012; 308 (10): 1024-33.
  • Tonkin A, Barter P, Best J, et al. National Heart Foundation of Australia and the Cardiac Society of Australia and New Zealand. Position statement on lipid management 2005. Heart Lung Circ 2005;14:275–91.
  • He K, Song Y, Daviglus ML, et al. Fish consumption and incidence of stroke: a meta-analysis of cohort studies. Stroke 2004;35:1538–42.
  • He K, Song Y, Daviglus ML, et al. Accumulated evidence on fish consumption and coronary heart disease mortality: a meta-analysis of cohort studies. Circulation 2004;109:2705–11.
  • Whelton SP, He J, Whelton PK, et al. Meta-analysis of observational studies on fish intake and coronary heart disease. Am J Cardiol 2004;93:1119-23.
  • Hooper L, Thompson RL, Harrison RA, et al. Omega 3 fatty acids for prevention and treatment of cardiovascular disease. Cochrane Database Syst Rev 2004;CD003177.
  • Yokoyama M, Origasa H, Matsuzaki M, et al. Effects of eicosapentaenoic acid on major coronary events in hypercholesterolaemic patients (JELIS): a randomised open-label, blinded endpoint analysis. Lancet 2007;369:1090–8.
  • Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto miocardico. Lancet 1999;354:447–55.
  • Turner M.B. Safety of fish oil and omega-3 fatty acids. Medicines Safety Update No.2; 2010. Therapeutic Goods Administration (accessed 24 June 2011).

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