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 The association had previously concluded that such supplements may
prevent death from heart disease in people who have already had a
heart attack, but warned there is no solid evidence that fish oil
can prevent heart disease in the first place, primarily because the
issue hasn't been studied.
"Reducing mortality by 10 percent would be important from a personal
level and a population level," coauthor Dr. David Siscovick said
about the new advice for people with heart failure.
The scientific advisory published in the association's journal
Circulation updates a 2002 guidance with data from 15 newer studies.
It comes at a time when about 19 million Americans - nearly 8
percent of the U.S. population - are already taking the supplements,
many of whom may not be getting any real value from them.
"This is very useful data. It's going to help stratify who might
benefit," said Dr. Karen Aspry of the Lifespan Cardiovascular
Institute in Providence, Rhode Island, who was not connected with
the analysis.
"Patients come in, they have questions, and clinicians are often
left scratching their heads because they think the data are all over
the place," she said. "This gives them some guideposts and a
framework so they can say, for this patient it's a good idea, and
for this other patient it's not a good idea because we don't have
enough data yet."
Supplement use may be common but there is a lack of evidence of
benefit in the general population, said Siscovick, who is senior
vice president for research at the New York Academy of Medicine in
New York City.
For most diseases, the evidence that omega-3 supplements offer a
benefit is sketchy.
In contrast, there is evidence that a diet rich in real fish lowers
the risk of death. That's why the AHA recommends that people eat at
least one or two servings of fatty fish each week.
In the new advisory, "we're not talking about dietary intake. We're
talking about the use of fish oil supplements," Siscovick said.
"People may view supplementation as the same as dietary intake of
fish but it isn't."
In its recommendation on heart failure, which occurs when the heart
can't pump blood efficiently, the advisory panel focused on a large
2008 study that found 840 milligrams per day of omega-3 fish oil cut
the rate of hospitalization by 8 percent and the death rate from
heart failure by 9 percent, compared to people receiving olive oil
supplements.
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The group also concluded there is no evidence that fish oil
supplements protect diabetics or people at risk for diabetes from
heart disease, or that fish oil supplements taken by the general
population prevent strokes, recurrent atrial fibrillation (a type of
irregular heartbeat) or atrial fibrillation after heart surgery.
The authors were unable to make recommendations for these groups
because there were no randomized controlled trials examining whether
supplements work for them. Trials currently in progress may offer
new evidence, they write.
Members of the review panel were divided on the question of whether
the supplements help people at high risk for heart disease. But most
concluded that fish oil treatment was not warranted.
Studies typically use 1,000 milligrams of omega-3 fatty acids a day.
Some supplement products advertised as 1000 mg of fish oil actually
contain a much smaller amount of omega-3 fatty acids.
The Siscovick team also noted that even in the few cases where fish
oil supplements might be benefiting people, the newer research isn't
showing the same degree of protection that older studies suggested.
That could be due to greater consumption of fish by the general
public or a broader use of heart drugs such as statins,
beta-blockers and aspirin, they said.
Aspry, director of Lifespan's Lipid and Prevention Program, agreed.
"When you start adding fish oils on top of modern therapies, the
positive effect of fish oils is much smaller."
SOURCE: http://bit.ly/2njahbu Circulation, online March 13 2017.
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