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 protect
against heart disease 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.
