Topic Overview

Eating fish, at least 2 servings each week, is part of a heart-healthy diet.

Fish oil supplements can lower triglycerides. But doctors do not agree about whether these supplements can help protect your heart.

Fish and fish oil do not lower cholesterol.

Some people take fish oil supplements to help lower triglycerides.

Do not take fish-oil or omega-3 fatty acid supplements to lower your risk of heart disease, heart attack, and stroke. Research has not shown that these supplements lower risk.footnote 2

Fish

Eating fish may help lower your risk of coronary artery disease. Health Canada recommends that healthy adults eat at least 2 servings of fish a week. Oily fish, which contain omega-3 fatty acids, are best for your heart. These fish include tuna, salmon, mackerel, lake trout, herring, and sardines.

Most people should not eat more than 150 g (5 oz) per week of fish that are known to have higher mercury levels. These include fresh or frozen tuna (not canned "light" tuna), shark, swordfish, marlin, orange roughy, and escolar. Some people need to restrict high-mercury fish even more:footnote 1

  • Nursing mothers or women who are or may become pregnant should limit high mercury fish intake to no more than 150 g (5.3 oz) a month.
  • Children 5 to 11 years of age should limit high mercury fish intake to no more than 125 g (4.4 oz) a month.
  • Children 1 to 4 years of age should limit high mercury fish intake to no more than 75 g (2.7 oz) a month.

Most people don't need to limit how much canned (white) albacore tuna they eat each week. But women who are or may become pregnant, nursing mothers, and children need to limit canned albacore tuna intake to no more than:footnote 1

  • 300 g (10.6 oz) each week for women who are or may become pregnant, or who are nursing.
  • 150 g (5.3 oz) each week for children 5 to 11 years of age.
  • 75 g (2.7 oz) each week for children 1 to 4 years of age.

Health Canada has no restrictions on eating fish and shellfish that are lower in mercury. These include salmon, rainbow trout, pollock, herring, shrimp, mussels, clams, and canned "light" tuna. Check local advisories about the safety of fish caught by family and friends in your local lakes, rivers, and coastal areas.

Why people may take fish oil

If you have severely high triglycerides, your doctor may recommend you take fish oil to try to prevent a problem with your pancreas called pancreatitis.

Sometimes people who don't eat fish take fish oil supplements. Some doctors think fish oil might help the heart because it has the omega-3 fatty acids from oily fish. But other doctors don't recommend these supplements to help the heart. That's because research has not proved that fish oil is helpful for everyone.footnote 3

If you have:footnote 3

  • Heart failure or have had a heart attack, fish oil supplements may have some benefit for you.
  • Other heart problems, supplements have not been shown to help your heart.
  • No heart problems, supplements have not been shown to help your heart.

You can buy fish oil supplements without a prescription. And sometimes doctors recommend a prescription fish oil medicine. This medicine is a highly concentrated form of omega-3 fatty acids, which are found in fish oil. This medicine is used along with diet and lifestyle changes for high triglycerides.

What else to know about fish oil

If you take a blood thinner, such as warfarin (Coumadin) or clopidogrel (Plavix), do not take fish oil without talking to your doctor first. Taking fish oil at the same time as blood thinners may cause problems with bleeding.

Talk with your doctor first if you want to take more than 3 grams a day of a fish oil supplement. Doses this high can also increase the risk of bleeding.

Some people burp more often or have a fishy taste in their mouths when they take fish oil supplements.

What other foods have omega-3 fatty acids

If you don't eat fish, you can get omega-3 fatty acids from foods such as omega-3 eggs, walnuts, flax seeds, and canola oil.

Most of these foods have a different kind of omega-3 fatty acid (called ALA) than the kinds of omega-3 fatty acids you get from eating oily fish (called DHA and EPA). There is not enough good research about whether ALA helps the heart.

Related Information

References

Citations

  1. Health Canada (2008). Mercury in fish: Consumption advice: Making informed choices about fish. Available online: http://www.hc-sc.gc.ca/fn-an/securit/chem-chim/environ/mercur/cons-adv-etud-eng.php.
  2. Fish oil supplements (2012). The Medical Letter on Drugs and Therapies, 54 (1401): 83-84.
  3. Siscovick DS, et al. (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-e884. DOI: 10.1161/CIR.0000000000000482. Accessed April 10, 2017.

Credits

Adaptation Date: 6/6/2018

Adapted By: HealthLink BC

Adaptation Reviewed By: HealthLink BC

Adaptation Date: 6/6/2018

Adapted By: HealthLink BC

Adaptation Reviewed By: HealthLink BC