(Reuters Health) - A new American Heart Association report says people with heart failure may live longer by taking omega-3 fish oil supplements because they seem to reduce the heart disease death rate by almost 10 percent.
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.
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: bit.ly/2njahbu Circulation, online March 13 2017.