Based on its review of all available scientific evidence, the AHA said omega-3 fatty acids benefit healthy people, people at high risk of cardiovascular disease and patients with cardiovascular disease.
People who have high triglycerides (blood fats) may benefit from taking oral fish oil supplements of two to four grams of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) per day. Even the one-gram daily dose recommended for heart patients may be more than they can easily get from diet alone. These people should talk to their doctors about taking supplements to reduce heart disease risk.
Patients taking more than three grams of omega-3 fatty acids from supplements should do so only under a physician’s care. Since omega-3 helps make the blood thinner to prevent it from clotting, high doses may also cause bleeding in some people.
In a statement, the AHA also recommends eating fish (particularly fatty fish) at least two times a week. Fish is a good source of protein without the high saturated fat found in fatty meat products. Fatty fish like mackerel, lake trout, herring, sardines, albacore tuna and salmon are also high in the two kinds of omega-3 fatty acids – EPA and DHA.
Omega-3 fatty acids may also be obtained from plant sources. Tofu and other forms of soybeans, canola, walnut and flaxseed, and their oils contain alpha-linolenic acid (LNA). This is a less potent kind of omega-3 fatty acid.
The public though is warned that some types of fish may contain significant levels of mercury, PCBs (polychlorinated biphenyls), dioxins and other environmental contaminants. Levels of these substances are generally higher in older, larger, predatory fish and marine mammals.
The benefits and risks of eating fish vary depending on a person’s stage of life:
• Children, pregnant and nursing women usually have low cardiovascular disease or CVD risk but may be at higher risk of exposure to excessive mercury from fish. Avoiding potentially contaminated fish is a higher priority for these groups.
• For middle-aged and older men, and post-menopausal women, the benefits of eating fish far outweigh the risks within the established guidelines of the FDA and Environmental Protection Agency.
• Eating a variety of fish will help minimize any potentially adverse effects due to environmental pollutants.
For those who are not fond of eating fish, taking fish oil supplements may be recommended.
The summary of recommendations for omega-3 fatty acid intake is as follows:
• For patients without documented coronary heart disease (CHD), eat a variety of fish (preferably fatty) at least twice a week. Include oils and foods rich in alpha-linolenic acid (flaxseed, canola and soybean oils, flaxseed and walnuts).
• For patients with documented CHD, consume approximately one gram of EPA plus DHA per day, preferably from fatty fish. EPA plus DHA supplements could be considered in consultation with a physician.
• For patients needing triglyceride lowering, take two to four grams of EPA plus DHA per day provided as capsules under a physician’s care.
New information has emerged about how omega-3 fatty acids affect heart function (including antiarrhythmic effects preventing irregular heartbeat), hemodynamics (cardiac circulation) and arterial endothelial function which is the precursor of atherosclerosis or the narrowing of the blood vessels. These findings are outlined in the AHA’s 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 thrombosis (blood clot formation), which can lead to heart attack and stroke;
• Decrease triglyceride levels;
• Decrease growth rate of atherosclerotic plaque;
• Improve the health of arteries; and
• Lower blood pressure (slightly).
Randomized clinical trials (RCTs) have shown that omega-3 fatty acid supplements can reduce cardiovascular events (death, non-fatal attacks, non-fatal strokes). They can also slow the progression of atherosclerosis in coronary patients.
Increasing omega-3 fatty acid intake through food is preferable. However, patients with coronary artery disease may not be able to get enough omega-3 (about one gram per day) by diet alone. These people may discuss with their doctors about taking a supplement to reduce their risk of coronary heart disease. Supplements can also help people with high triglycerides, who need even larger doses (two to four grams per day).
A locally available brand of omega-3 supplement is Omegabloc, an over-the-counter food supplement available in most Mercury Drugstores nationwide. It is manufactured by NOW International, one of the leading manufacturers of food supplements in the United States.