| Using Omega-3 Fatty Acids to Prevent Heart
Disease American Family Physician, Nov 15, 2000 by Richard
Sadovsky
For the past 30 years, omega-3 fatty acids (w-3 FAs) (eicosapentaenoic
[EPA] and docosahexaenoic [DHA] acids) have been associated
with reduced rates of myocardial infarction. Several
prospective studies examining fish intake and coronary heart
disease (CHD) confirmed that regular fish consumption (one
or more meals per week) was associated with a risk-adjusted
reduction in sudden death compared with low consumption.
Other studies, however, have failed to document benefits
from fish consumption. O'Keefe and Harris review the
clinical implications of studies evaluating w-3 FA
supplementation.
Three prospective, randomized, controlled studies
evaluated the benefits of w-3 FA intake in the secondary
prevention of heart disease. The Diet and Reinfarction Trial
randomized 2,013 men to usual care or a diet high in w-3 FAs
following myocardial infarction. Patients in the latter
group showed a 29 percent reduction in overall mortality
over the next two years. The incidence of fatal myocardial
infarctions decreased significantly as well. Another trial
randomized a similar population to usual care or fish oil
supplementation. After one year, there was a significant
decrease in serious ventricular arrhythmias and total
cardiac events in patients taking the fish oil supplement.
The largest study was the GISSI Prevenzione Trial, in which
most patients were randomized to usual care or increased
intake of w-3 FA following myocardial infarction. After 3.5
years, patients consuming an increased amount of dietary w-3
FAs had a statistically significant reduction in total
mortality and sudden death. This last study also suggested
that the difference in outcome appeared to be independent of
traditional risk factors such as lipids and blood pressure,
and was additive to the benefit conferred by standard
preventive therapies. None of the studies reported serious
adverse events associated with increased w-3 FA intake.
The mechanisms responsible for the protective effect of
increased w-3 FA intake include antidysrhythmic effects,
decreased fibrinogen levels and platelet counts, modestly
reduced blood pressure and decreased cell proliferation.
Improvements in arterial compliance and endothelial
function, as well as antiplatelet and anti-inflammatory
effects also have been documented. The U.S. Food and Drug
Administration has concluded that dietary intake of up to 3
g per day of EPA plus DHA is "Generally Recognized as Safe."
Even though w-3FA supplementation results in a modest
increase in low-density lipoprotein, it is more than offset
by marked reductions in atherogenic very-low-density
lipoprotein triglyceride levels.
The authors conclude that w-3 FA supplementation should
be considered in patients with documented CHD, especially if
they have risk factors for sudden cardiac death. For a list
of these risk factors, see the accompanying table. The
recommended intake of 1 g per day may be appropriate for all
adults with a high CHD risk factor profile. A dietary
approach can include four 3-oz servings of oily fish (e.g.,
salmon, herring, mackerel) weekly. Fish oil capsules can be
used as well. The benefits of w-3 FA supplementation appear
to be independent of and additive to those of other
therapeutic interventions for CHD, such as statins, aspirin
and antihypertensive agents.
RICHARD SADOVSKY, M.D.
O'Keefe JH Jr, Harris WS. Omega-3 fatty acids: time for
clinical implementation? Am J Cardiol May 15, 2000;
85:1239-40.
Risk Factors for Sudden Cardiac Death
Prior infarction
Left ventricular dysfunction
Ventricular dysrhythmia
Left ventricular hypertrophy |
