Scientists noticed a curiously low incidence of heart disease among Greenland Eskimos despite their high-fat diet. The reason? They were eating fish rich in omega-3 fatty acids. Later studies confirmed the cardioprotective effect of fish oils while uncovering other benefits as well.
What Is Fish Oil
The fat in fish has a form of polyunsaturated fatty acids called omega-3s. These differ from the polyunsaturated fatty acids found in vegetable oils (called omega-os), and they have different effects on the body. (Fish don't manufacture such fats but get them from the plankton they eat; the colder the water, the more omega-3s the plankton contains.) The two most potent forms of omega-3s, eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA), are found in abundance in cold-water fish such as salmon, trout, mackerel, and tuna (including the canned variety). The sources of a third type of omega-3, alpha-linolenic acid (ALA), are certain vegetable oils (such as flaxseed oil) and leafy greens (such as purslane). However, ALA doesn't affect the body in the same way that EPA and DHA do.
What Does Omega-3 Do
Omega-3s play a key role in a range of vital body processes, from blood pressure and blood clotting to inflammation and immunity. They may be useful for preventing or treating many diseases and disorders.
• Help prevent cardiovascular disease; useful for other circulatory conditions as well.
• Block disease-related inflammatory responses in the body.
• May lower blood pressure.
Fish oils appear to reduce the risk of heart disease. They do this in several ways. Most importantly, the presence of omega-3s makes platelets in the blood less likely to clump together and form the clots that lead to heart attacks. Next, omega-3s can reduce triglycerides (blood fats related to cholesterol) and may lower blood pressure. In addition, recent research has shown that omega-3s strengthen the heart's electrical system, preventing heart-rhythm abnormalities. However, the strongest evidence for the cardiovascular benefits of fish oils comes from studies in which the participants ate fish rather than taking fish oil supplements.
Within the artery walls, omega-3s inhibit inflammation, which is a factor in plaque buildup As a result, therapeutic doses of fish oils are one of the few successful ways to prevent the reblockage of arteries that commonly occurs after angioplasty, a procedure in which a small balloon is guided through an artery to a blockage and then is inflated to compress plaque, widen the vessel, and improve blood flow to the heart. This effect on blood vessels makes fish oils helpful for Raynaud's disease as well.
Omega-3s are also effective general anti-inflammatories, useful for joint problems, lupus, and psoriasis. Studies indicate that people with rheumatoid arthritis experience less joint swelling and stiffness, and may even be able to manage on lower doses of anti-inflammatory drugs, when they take fish oil supplements. In a yearlong study of people with Crohn's disease (a painful type of inflammatory bowel disease), 69% of those taking enteric-coated fish oil supplements (about 3 grams of fish oils a day) stayed symptom-free, compared with just 28% of those receiving a placebo. Fish oils may also help ease menstrual cramps. In addition, omega-3s may play a role in mental health. Some experts believe there's a correlation between the increasing incidence of depression in the United States and the declining consumption of fish. And a preliminary study suggested that omega-3 fatty acids may reduce the severity of schizophrenia by about 25%.
How To Take Omega-3
For heart disease, Raynaud's disease, lupus, and psoriasis:
Take 3,000 mg of fish oils a day. For rheumatoid arthritis: Take 6,000 mg a day. For inflammatory bowel disease: Take 5,000 mg a day.
Guidelines For Use
Fish oil supplements are not necessary for heart disease prevention or treatment if you eat fish at least twice a week. However, supplements are recommended for rheumatoid arthritis and other inflammatory conditions. Take capsules with meals. Supplements may be easier to tolerate if you take them in divided doses; for example, 1,000 mg three times a day, instead of 3,000 mg in one sitting.
Possible Side Effects
Fish oil capsules may cause belching, flatulence, bloating, nausea, and diarrhea. Very high doses may result in a slightly fishy body odor. There's some concern high doses can lead to internal bleeding. But a study of people with heart disease who took 8,000 mg of fish oil supplements in addition to aspirin (an anticoagulant) found no increase in internal bleeding.
Some studies found high doses of fish oils worsen blood sugar control in people with diabetes; others have shown no effect. To be safe, people with diabetes should not take more than 2,000 mg of fish oil supplements a day without the advice of their doctor.
Individuals with high fasting triglycerides should be careful if they also have high LDL ("bad") cholesterol: Therapeutic doses of fish oils can increase LDL. Garlic supplements, however, may be the remedy. One study found garlic reversed the fish oils' LDL-raising effect. For rheumatoid arthritis and other inflammatory conditions, eating fish is probably not sufficient, and fish oil supplements are recommended.
• Because omega-3 fatty acids inhibit blood clotting, consult a doctor before using fish oil supplements if you have a blood disorder or if you are taking anticoagulant medications.
• Don't take fish oil supplements two days before or after surgery.
• If you find you can't tolerate one brand of fish oil supplements, try another. Side effects vary from brand to brand.
• Don't try to save money by buying fish oil supplements in bulk because they can go rancid very quickly. Always store fish oil pills in the refrigerator.
• Don't buy cod liver oil to get your omega-3s. It contains high amounts of vitamin A and vitamin D, both of which can be toxic in large doses.
• According to a preliminary study from the University of California, Los Angeles, omega-3s may help tight breast cancer and maintain healthy breast tissue. Animal studies also indicate that fewer breast tumors develop when fish oils are part of a healthy diet.
• Fish oils may help prevent colon cancer. Participants in a recent study who took 4,400 mg of fish oils a day produced much less of one potent carcinogen associated with colon cancer than those on a placebo.