Fats that are necessary for good health and, because they’re not made by the body, must be consumed in the foods we eat. The two types of essential fatty acids are omega-6 and omega-3 fatty acids. While both types are necessary for good health, many nutrition experts believe that the modern-day Western diet is too rich in omega-6 fatty acids and somewhat deficient in omega-3 fatty acids. They also believe that this imbalance may contribute to such medical problems as cardiovascular disease, cancer, asthma, diabetes, and depression.
Omega-6 fatty acids are found in cereals, eggs, poultry, vegetable oils, and margarines. There are three types of omega-3 fatty acids that are important in terms of nutrition: alpha-linolenic acid (LNA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). LNA is found in leafy green vegetables, canola oil, walnuts and walnut oil, and flaxseed and flaxseed oil (sold in health-food stores both as food and in supplements). EPA and DHA are found in abundance in fish, especially fatty fish such as salmon, herring, mackerel, lake trout, and tuna.
A number of randomized clinical trials have shown that eating a diet rich in omega-3 fatty acids can lower a person’s risk of having a heart attack. Omega-3 fatty acids may do this through a number of factors that affect heart disease. Studies have shown that they can reduce LDL (low-density lipoprotein, or “bad”) cholesterol and triglyceride levels and increase levels of HDL (high-density-lipoprotein, or “good”) cholesterol. Omega-3 fatty acids also appear to slightly lower blood pressure and to reduce the blood’s tendency to clot, which can in turn lower the risk of heart disease. Other studies suggest that fish oil may help reduce symptoms of depression, slow cognitive decline in the elderly, and ease the symptoms of rheumatoid arthritis.
Based on the proven heart-protective effects of omega-3 fatty acids, the American Heart Association recommends that everyone eat fish (particularly fatty fish) at least twice a week. The group also recommends eating foods rich in LNA, including tofu and other forms of soybeans, walnuts, flaxseed, and canola, walnut, and flaxseed oils. For individuals with known heart disease, it recommends consuming 1 gram of EPA and DHA per day, preferably from fatty fish. (One gram of omega-3 fatty acids can be found in approximately 3 ounces of salmon or 4 ounces of canned albacore tuna.) The association says that some of the recommended omega-3 fatty acids could be taken in the form of fish oil or flaxseed supplements that contain both EPA and DHA, but it recommends checking with your doctor first. For people with high triglyceride levels, it recommends consuming 2–4 grams daily of EPA and DHA in the form of capsules — again, under the supervision of a doctor.