Is there something fishy going on with omega-3 fatty acids?
For years, major health and medical organizations have recommended fish oil supplements rich in omega-3s to reduce the threat of heart disease. In Europe, where support is particularly enthusiastic, a doctor's failure to recommend the supplements is viewed by some as bordering on malpractice.
But several recent studies have raised questions about the benefits of fish oil, sparking no small amount of confusion. A report published Wednesday in the Journal of the American Medical Assn. clouded the picture further by concluding that omega-3 polyunsaturated fatty acids did not lower the risk of heart attack, stroke or premature death.
The study, by medical researchers at the University of Ioannina in Greece, did not involve a new clinical trial of the supplement. Instead, it reexamined the results of 20 previous studies dating back to 1989 that included nearly 70,000 patients.
Among other observations, study authors said that early trials of omega-3 supplements and cardiovascular health "showed strong, significant effect." However, as more randomized studies were performed, "the effect became weaker and nonsignificant."
One of the reasons for this, according to the authors, is that an early and influential trial was conducted as an open-label study, in which patients and researchers knew when they were taking the supplement. That study involved mostly men who had suffered heart attacks, said Dr. Moses S. Elisaf of the University Hospital of Ioannina, the study's senior author.
"This evidence," he said, "should not be generalized to any type of patients or apparently healthy individuals."
Much of the recent controversy involving omega-3 has to do with conflicting recommendations.
In the United States, the Food and Drug Administration has approved omega-3 use only as a triglyceride-lowering agent, whereas some European authorities recommend its use for patients who have suffered a heart attack or other cardiovascular problems.
"Varying labeling indications [cause] confusion in everyday clinical practice," the study authors wrote.
Dr. Robert Bonow, a Chicago cardiologist who was not involved in the study, said he tended to agree with the authors' conclusion that not everyone would be helped by taking omega-3 supplements. Bonow, a former president of the American Heart Assn., said there was no evidence omega-3 prevented heart attacks and said that for most people, any potential benefits of supplementation probably paled in comparison with exercising, maintaining a proper weight and addressing high cholesterol and high blood pressure.
However, Bonow said it appeared the supplement was helpful to people with very weak hearts. One of the studies included in the JAMA analysis made a strong case that patients with chronic heart failure benefited from omega-3s. "There may be benefits here in stabilizing the rhythm of the heart," he said.
Omega-3s are also effective in reducing triglycerides, fats that circulate in the blood and can be dangerous at high levels. "Triglycerides also respond to diet and exercise, but if they're very high we do recommend omega-3s for that effect," Bonow said.