Topic Overview

Eating fish, at least 2 servings each week, is part of a heart-healthy diet. But fish and fish oil supplements do not help lower cholesterol.

Some people take fish oil supplements to help lower triglycerides. Fish oil supplements can lower triglycerides.

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


Eating fish may help lower your risk of heart 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.

Health Canada recommends that women who may become pregnant, pregnant women, and nursing mothers should only eat 2 servings a month of fresh or frozen tuna, shark, swordfish, marlin, orange roughy, and escolar, because these fish have higher mercury concentrations. Children should only eat 1 to 2 servings of these fish per month, depending on their age.footnote 1 But for middle-aged and older people, the protection that fish gives the heart outweighs the risks of eating these fish. Eating a variety of fish may reduce the amount of mercury you eat.

Fish oil

Fish oil capsules that you can buy without a prescription can have significant side effects. Because of these side effects, many doctors recommend eating 2 servings of fish a week rather than taking fish oil capsules. The side effects of fish oil capsules include:

  • Large amounts of omega-3 fatty acids (the main type of fatty acid in fish oil) can greatly reduce the ability of the blood to clot normally.
  • Fish oil can cause nausea, diarrhea, belching, and a fishy taste in the mouth.
  • Taking large amounts of fish oil greatly increases the number of calories in the diet. Some suggested doses add more than 200 calories a day.

Related Information



  1. Health Canada (2008). Mercury in fish: Consumption advice: Making informed choices about fish. Available online:
  2. Fish oil supplements (2012). The Medical Letter on Drugs and Therapies, 54 (1401): 83–84.


ByHealthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Donald Sproule, MDCM, CCFP - Family Medicine
Specialist Medical Reviewer Rhonda O'Brien, MS, RD, CDE - Certified Diabetes Educator

Current as ofFebruary 20, 2015