Taking fish oil before and after cardiac surgery didn’t prevent a form of irregular heartbeat in a study finding that raises more questions about the extent of the supplement’s health benefits.
Trial participants given fish oil, a form of omega-3 fatty acid that doctors recommend for some heart patients, were just as likely to develop atrial fibrillation after surgery as those not given the supplement, the study showed. Atrial fibrillation, a flutter of the heart that can cause blood clots and strokes, occurs in 1 in 3 people after a heart operation.
The research, presented today at the American Heart Association’s annual meeting in Los Angeles, suggests there are limitations to fish oil’s heart benefits. Past studies have shown fish oil can lower unhealthy blood fats, blood pressure and reduce the risk of a second heart attack. Others in the past two years have shown contradictory findings.
Fish oil “may offer a number of protective effects to prevent cardiovascular disease, but if you look at this particular population of surgical patients and short-term use, fish oil does not help avoid atrial fibrillation,” said Dariush Mozaffarian, co-author of the study and an associate professor at Harvard medical School, said in a statement.
The American Heart Association advises patients with chronic heart disease to consume one gram of omega-3 fatty acids a day, preferably by eating fish. Some patients may need to take fish oil supplements to reach that threshold in consultation with their physicians, according to the AHA.
Still, a review of 20 trials over 24 years published in the Journal of the American Medical Association in September found that fish oil supplements didn’t lower the risk for a range of illnesses, including heart attacks, strokes or death. A study in 2010 published in the same journal found fish oil didn’t prevent recurrences of atrial fibrillation.
Part of the difference between studies could be the type of patients being followed, said Mozaffarian. It may be more difficult to see a benefit in patients already taking drugs to control their cholesterol and blood pressure or in those not at high risk for heart disease.
The study released today followed 1,516 patient who were given their a placebo or 8 milligrams of omega-3 fatty acids two to five days before surgery and 2 grams a day for the 10 days following surgery. About 30 percent of patients getting either a placebo or fish oil had post-operative atrial fibrillation.
There was also no difference between the two groups in the number of deaths 30 days after surgery or the rate of heart attacks or strokes while patients recovered. Patients taking fish oil spent the same amount of time in the intensive care unit and hospital as those given a placebo.
The study was funded by the National Institutes of Health, GlaxoSmithKline Plc (GSK), Sigma Tau Pharmaceuticals Inc., and Pronova BioPharma AS. (PRON) Those companies either sell or are testing products that use Omega-3 fatty acids to treat various conditions.
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