that the omega-3 fatty acids they contain help protect against
cardiovascular disease (CVD) and sudden death caused by heart rhythm
abnormalities. But there is conflicting evidence from several research
studies and, in theend, these supplements areprobably not helpful.
Results of a New Study
The fatty acids thought to help protect against CVD are called
eicosapentaenoicacid (EPA) and docosahexaenoic acid (DHA). In
reviewing this ongoing issue, the latest results are from a
meta-analysis published recently in Archives of Internal Medicine.
This report examined 14 research trials that enrolled20,485 patients.
These patients, all with known aCVD, took either a placeboor fish oil
supplements. Theaverage dose was 1.7 gram/day of EPA and DHA. The
results showed that supplementation did not reduce the risk of CVD
events, sudden cardiac death, heart attacks, strokeand transient
ischemic events, or deaths from all causes. The authors concluded that
fish oil supplements were not beneficial in secondary prevention
(preventative measures used in people with a prior history of CVD.)
Results of Previous Studies Differ
One reason for the popularity of fish oil supplementation was the 1999
report of a large Italian study which followed people who took fish
oil supplements for a period of 3.5 years, startingwithin 3 months
after a heart attack. Those taking the supplements significanty
lowered their risk for overall death as well as a combination of CVD
outcomes, compared to study participants who did not take fish oil
after a heart attack. While that sounded promising, two other research
trials looking at secondary prevention, published in 2010, found
different results, as did the meta-analysis described above. These
trials found that fish oil supplements offered no protection against
CVD events. What could be the reason?
There are a couple of possible explanations for the different results
of the latest studies:
1) accurate determination of the benefits of preventive measures
requires a longer follow-upthan employed in any of these studies; and,
2) any possible benefits of fish oil supplements were not apparent in
participants in the later studies because their CVD risk was reduced
by taking the new medications to control cholesterol levels and blood
pressure.
In addition, an earlier meta-analysis also had found no CVD benefits
of fish oil supplements in people with no prior history of CVD (i.e.,
primary prevention).
Should you continue to take fish oil supplements?
I think not, but there does remain the possibility that fish oils
provide some protection against CVD. Thecontroversy may be resolved by
results of the ongoing vitamin D and omega-3 trial that will enroll
20,000 men older than 50 and women older than 55.
Omega-3s are Essential in Your Diet
Despite the disappointing research results around fishoil, omega-3
fatty acids arean essential dietary component since humans can't make
these fats.
If you decide to continue to take fish oil supplements, you'll want to
understand that the omega-3 fatty acids EPA and DHA comprise only
about 20 percent of most supplements. Meanwhile, whether you have CVD
or not, you should eat at leasttwo servings of marine fishweekly
because they not only contain omega-3 fattyacids but may also replace
your intake of less healthy red meat.
One final point about fish oil—there is even less evidence to support
other beneficial claims for these supplements, for example to improve
memory and joint pains of rheumatoid arthritis. However, strong
evidence does show that large doses of fish oil supplements
effectively lower blood triglycerides (but do not raise HDL
cholesterol or lower LDL cholesterol levels).