Omega-3 fatty acids are called essential fats because the body cannot produce them; they must be consumed from foods in order to survive. Fish are the primary dietary source of omega-3, although some plants also contain omega-3 fatty acids as well.
Two kinds of omega-3 fatty acids are found in fish, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The role of EPA and DHA in the prevention of cardiovascular disease (CVD) has been extensively studied. The form of omega-3 in plants is called alpha-linolenic acid (ALA), which is less potent on CV health than EPA and DHA, but still provides health benefits.
How are Omega-3 fatty acids beneficial?
Here's how omega-3 fatty acids may protect you from cardiovascular disease:
Omega-3 fatty acids are found in fish and have many health benefits. To benefit from omega-3 fats, the American Heart Association recommends most people consume two meals of fish every week (about 6-8 ounces of fish).
- Lower risk of sudden death. Omega-3 fatty acids have been shown to significantly reduce the risk of sudden death caused by cardiac arrhythmias and all-cause mortality in people with existing cardiovascular disease.
- Reduce blood clot formation. Omega-3 fatty acids act as a natural anticoagulant by altering the ability of platelets in the blood to clump together.
- Inhibit the growth of plaque. Omega-3 fatty acids help keep the lining of the arteries smooth and clear of damage that can lead to thickening and hardening of the arteries.
- Decrease triglycerides. High blood triglycerides are associated with an increased risk for heart disease. Omega-3 fatty acids decrease the rate at which triglycerides are produced in the liver.
- May increase levels of the good cholesterol, high-density lipoprotein (HDL). Because omega-3 fatty acids lower triglyceride levels, they may also increase HDL, the “good” cholesterol that protects against the development of heart disease.
- Have anti-inflammatory properties. The development of atherosclerosis (hardening of the arteries) is thought to involve your body’s inflammatory response. Omega-3 fatty acids reduce the production of substances that are released during the inflammatory response and in doing so, prevent substances from accumulating and sticking to the lining of the arteries.
- May lower blood pressure. Several studies have examined the effect of omega-3 fatty acids on blood pressure. Those who eat fish tend to have lower incidence of high blood pressure.
Cold-water varieties of fish like mackerel, tuna, salmon, sardines and herring contain high amounts of omega-3 fatty acids.
How much Omega-3 do I need?
The American Heart Association recommends that patients without documented coronary heart disease, eat a variety of fatty fish (see list below) and aim for at least two servings per week (total of at least 6-8 ounces).
If you have heart disease, your health care professional may recommend you increase your food sources of omega-3 to reach a daily goal of one gram of EPA + DHA. If this amount is too difficult to achieve from diet alone, your health care provider may suggest taking a fish oil supplement.
If you have high triglyceride levels (including those who are taking triglyceride-lowering medications), your health care provider may also recommend you increase food sources of omega-3. If these strategies are not effective, your provider may tell you to incorporate fish oil supplements into your diet. Generally, two-four grams of EPA + DHA are recommended daily. This amount has been shown in research studies to lower triglycerides approximately 25%-35%. Take note that a high intake of omega-3 fatty acids can cause bleeding in some people; so if you are taking 3 grams or more daily, consult with your physician.
Amount of Omega-3 Fatty Acids in Selected Fish and Seafood
|Fish ||Serving Size ||Amount of Omega-3 Fat |
|Mackerel - Atlantic ||3 ounces (100 grams) ||2.5-2.6 grams |
|Salmon - Atlantic Farmed ||3 ounces (100 grams) ||1.8 grams |
|Herring ||3 ounces (100 grams) ||1.7-1.2 grams |
|Tuna - Blue Fin ||3 ounces (100 grams) ||1.6 grams |
|Lake Trout ||3 ounces (100 grams) ||1.6-1.3 grams |
|Anchovy ||3 ounces (100 grams) ||1.4 grams |
|Tuna - Albacore ||3 ounces (100 grams) ||1.3 grams |
|Lake White Fish - freshwater ||3 ounces (100 grams) ||1.3 grams |
|Bluefish ||3 ounces (100 grams) ||1.2 grams |
|Halibut ||3 ounces (100 grams) ||0.9 grams |
|Striped Bass ||3 ounces (100 grams) ||0.8 grams |
|Sea Bass (mixed species) ||3 ounces (100 grams) ||0.65 grams |
|Tuna, white meat canned ||3 ounces drained ||0.5 gram |
What about mercury in fish? Shouldn't I be concerned?
Mercury occurs naturally in the environment and as a result of industrial pollution. It falls from the air and can accumulate in streams and oceans and is converted to methylmercury in the water. Methylmercury, in excess, can be harmful to health, especially the health of an unborn baby or young child.
Fish that are particularly high in mercury include shark, swordfish, tilefish, and King mackerel. These fish should be limited by everyone, and avoided by pregnant/nursing women and young children. Pregnant and lactating women can still safely eat 12 ounces/week of fish that are not high in mercury, including shellfish, canned fish, smaller ocean fish, and farm-raised fish.
Albacore Tuna has more mercury than canned light tuna, therefore limit intake of albacore tuna to no more than 6 ounces per week.
What if I have an allergy to fish, or choose not to eat fish?
Several plants contain the omega-3 fatty acid ALA, although ALA is broken down minimally to EPA + DHA in the body. Despite this, there are studies linking diets rich in ALA to lower risk of cardiovascular disease.
Good sources of ALA are flaxseeds, flaxseed oil, walnuts, soy foods, and canola oil. Another source of ALA is algae or algae oil, which is broken down to DHA. Many foods that are fortified with omega-3 often use algae oil. These are excellent omega-3 options for vegetarians that do not eat fish.
Currently, there are no established serving size recommendations for ALA rich foods. Adding these foods to your diet regularly may derive additional heart-health benefits. Good sources of ALA include ground or milled flaxseeds, chia seeds, soybeans, walnuts, and canola oil.