In the never-ending quest to prevent heart attacks, many populations with low rates of heart disease have been studied. What are the unique properties of these people that protect them from heart disease? One factor that seems to be protective is the regular consumption of fish, especially fish high in omega 3 fatty acids.
Omega 3 fatty acids are polyunsaturated fatty acids that can be found in plants (alpha linolenic acid) and fish (eicosapentaenoic acid or EPA and docosahexaenoic acid or DHA). The omega 3 fatty acids from fish are felt to be especially cardio protective. The oily (dark meat) fish that contain omega 3 fatty acids include halibut, herring, mackerel, oysters, salmon, sardines, trout, tuna, cod, char and mussels. Fish oil containing omega 3 fatty acids has several properties that may be beneficial for heart heath. It lowers triglycerides and may lower blood pressure while improving the health of arteries. Omega 3 fatty acids stabilize heart membranes and reduce the risk of heart arrhythmias. Fish oil may also be a blood thinner and it may have anti-inflammatory effects as well. Do the benefits of fish oil translate into a lower risk for heart disease?
In studies of populations who consume large amounts of fish rich in omega 3 fatty acids, it was found that there was a very low risk for death from heart artery disease. For example, one of those populations, the Eskimos in Alaska, eat on average about 20 times the amount of omega 3 fatty acids as compared to people in the continental United States. In studies of patients without previous heart artery disease, those with higher intake of omega 3 fatty acids had a lower risk of dying from a heart attack. The death rate is 15% lower for weekly consumption of fish and 23% lower if fish is eaten two to four times per week. In patients with a prior heart attack, fish consumption was also associated with lower rates of cardiac death. The effect of fish oil seems to be in the reduction of sudden cardiac (arrhythmia related) deaths rather than nonfatal heart attacks (where there is no real benefit). Fish oil may not stabilize heart artery plaque (which would lower the overall rate of heart attacks). Because of these studies, the American Heart Association recommends that patients who have heart artery disease eat oily fish two times per week. In addition, the heart healthy Mediterranean Diet advocates for two or more servings of fish per week.
If consuming fish is good for the heart, is the same true for fish oil supplements containing omega 3 fatty acids? Fish oil supplements also lower triglycerides and LDL cholesterol but it is more controversial whether they reduce the risk for heart disease. In general, these supplements are safe although they can increase the risk for bleeding. Early studies showed a benefit for fish oil supplements but more recent data don’t show the same benefit. A recent study of 77,000 patients given supplements with omega 3 fatty acids for 4 years showed no reduction in heart attacks, stroke, cancer or death. There may be several reasons for the difference. More recent studies include higher consumption of fish; people have gotten the message and have increased their fish intake on their own. Adding fish oil supplements to a diet that includes fatty fish wouldn’t reduce risk further. In addition, more recent studies include patients receiving maximal therapy for heart disease. Adding fish oil supplements won’t reduce risk further. The American Heart Association reviewed all of the available data on fish oil supplements and recommended the following. For patients without heart disease there is not enough data to recommend fish oil supplements. For patients with heart artery disease, already on optimal medical treatment, the role of supplements is not settled. Given the fact that fish oil supplements are relatively safe, their addition may be reasonable.
The best way to prevent heart artery disease is to exercise regularly and follow a prudent diet, including a good amount of fish. Fish oil (omega 3) supplements can be used for patients with established heart artery disease, but only after other medications, especially statins, are maximized and with the realization that the benefit of the supplement may only be minor.