Omega-3 fatty acids are considered essential fatty acids, which means that they are essential to human health but cannot be manufactured by the body. For this reason, omega-3 fatty acids must be obtained from food. Omega-3 fatty acids can be found in fish and certain plant oils. It is important to maintain an appropriate balance of omega-3 and omega-6 (another essential fatty acid) in the diet as these two substances work together to promote health. Also known as polyunsaturated fatty acids (PUFAs), omega-3 and omega-6 fatty acids play a crucial role in brain function as well as normal growth and development.
There are three major types of omega 3 fatty acids that are ingested in foods and used by the body: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Once eaten, the body converts ALA to EPA and DHA, the two types of omega-3 fatty acids more readily used by the body. Extensive research indicates that omega-3 fatty acids reduce inflammation and help prevent certain chronic diseases such as heart disease and arthritis. These essential fatty acids are highly concentrated in the brain and appear to be particularly important for cognitive and behavioral function. In fact, infants who do not get enough omega-3 fatty acids from their mothers during pregnancy are at risk for developing vision and nerve problems.
Omega-3 fatty acids benefit the heart of healthy people, and those at high risk of — or who have — cardiovascular disease.
We recommend eating fish (particularly fatty fish) at least two times a week
Fish is a good source of protein and doesn’t have the high saturated fat that fatty meat products do. Fatty fish like mackerel, lake trout, herring, sardines, albacore tuna and salmon are high in two kinds of omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
We also recommend eating tofu and other forms of soybeans, canola, walnut and flaxseed, and their oils
These contain alpha-linolenic acid (LNA), which can become omega-3 fatty acid in the body. The extent of this modification is modest and controversial, however. More studies are needed to show a cause-and-effect relationship between alpha-linolenic acid and heart disease.
The table below is a good guide to use for consuming omega-3 fatty acids.
Summary of Recommendations for Omega-3 Fatty Acid Intake
Patients taking more than 3 grams of omega-3 fatty acids from capsules should do so only under a physician’s care. High intakes could cause excessive bleeding in some people.
In 1996 the American Heart Association released its Science Advisory, “Fish Consumption, Fish Oil, Lipids and Coronary Heart Disease.” Since then important new findings have been reported about the benefits of omega-3 fatty acids on cardiovascular disease. These include evidence from randomized, controlled clinical trials. New information has emerged about how omega-3 fatty acids affect heart function (including antiarrhythmic effects), hemodynamics (cardiac mechanics) and arterial endothelial function. These findings are outlined in our November 2002 Scientific Statement, “Fish Consumption, Fish Oil, Omega-3 Fatty Acids and Cardiovascular Disease.”
The ways that omega-3 fatty acids reduce CVD risk are still being studied. However, research has shown that they:
- decrease risk of arrhythmias, which can lead to sudden cardiac death
- decrease triglyceride levels
- decrease growth rate of atherosclerotic plaque
- lower blood pressure (slightly)
What do epidemiological and observational studies show?
Epidemiologic and clinical trials have shown that omega-3 fatty acids reduce CVD incidence. Large-scale epidemiologic studies suggest that people at risk for coronary heart disease benefit from consuming omega-3 fatty acids from plants and marine sources. The ideal amount to take isn’t clear. Evidence from prospective secondary prevention studies suggests that taking EPA+DHA ranging from 0.5 to 1.8 grams per day (either as fatty fish or supplements) significantly reduces deaths from heart disease and all causes. For alpha-linolenic acid, a total intake of 1.5–3 grams per day seems beneficial.
Randomized clinical trials have shown that omega-3 fatty acid supplements can reduce cardiovascular events (death, non-fatal heart attacks, non-fatal strokes). They can also slow the progression of atherosclerosis in coronary patients. However, more studies are needed to confirm and further define the health benefits of omega-3 fatty acid supplements for preventing a first or subsequent cardiovascular event. For example, placebo-controlled, double-blind, randomized clinical trials are needed to document the safety and efficacy of omega-3 fatty acid supplements in high-risk patients (those with type 2 diabetes, dyslipidemia, hypertension and smokers) and coronary patients on drug therapy. Mechanistic studies on their apparent effects on sudden death also are needed.
Increasing omega-3 fatty acid intake through foods is preferable. However, coronary artery disease patients may not be able to get enough omega-3 by diet alone. These people may want to talk to their doctor about taking a supplement. Supplements also could help people with high triglycerides, who need even larger doses. The availability of high-quality omega-3 fatty acid supplements, free of contaminants, is an important prerequisite to their use.