Supplements containing omega-3 fatty acids, the oils abundant in fatty fish, may not help reduce the risk of heart problems in people already at high risk, according to a study published in JAMA Cardiology.

Previous research has linked omega-3s to a lower risk of abnormal heartbeats, less fats in the blood, reduced risk of artery-clogging deposits known as plaque, and slightly lower blood pressure.

For the current study, researchers examined data from 10 trials with a total of 77,917 participants with a previous heart attack or stroke or health problems like diabetes. Most had been randomly assigned to take either omega-3 fatty acid supplements or a placebo, or dummy pill, for at least one year.

During follow-up, 2,695 people (3.5%) died from heart disease, while 2,276 (2.9%) had nonfatal heart attacks, 1,713 (2.2%) had strokes and 6,603 (8.5%) had procedures to reopen clogged arteries. Risks for these outcomes were the same whether or not people took omega-3 fatty acid supplements, researchers report in JAMA Cardiology.

“The results . . . demonstrated no beneficial effect of omega-3 fatty acid supplements for prevention of cardiovascular disease, overall, or on any subtype of cardiovascular disease, or on cardiovascular disease in any subgroup of the population,” said senior study author Dr. Robert Clarke, a public health researcher at the University of Oxford in the UK.

“Thus, the results . . . provide no support for the current guidelines of the American Heart Association that advocate that patients with prior coronary heart disease take omega-3 fatty acid supplements for the prevention of cardiovascular disease,” Clarke said by email.

Most of the trials in the current study included different doses and combinations of two omega-3s: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Across the trials, people took these supplements for an average of one to six years.

While taking these supplements appeared tied to a slightly lower risk of death from heart disease, nonfatal heart attacks, and all coronary heart disease events, the differences in each case were too small to rule out the possibility that they were due to chance.

Even if there isn’t overwhelming evidence that omega-3 supplements protect against heart disease, it still may be a reasonable choice for patients because the supplements are inexpensive and safe with virtually no serious side effects, said Dr. Carl Lavie, the University of Queensland School of Medicine in New Orleans, Louisiana.

People already taking omega-3 supplements shouldn’t stop, and there are other reasons beyond just heart health to consider this option, said Dr. Dominik Alexander, a researcher at the EpidStat Institute in Ann Arbor, Michigan, who wasn’t involved in the study.

“In addition to maintaining a healthy body weight, habitually engaging in physical activity, and not smoking, consumers should regularly eat fatty fish as part of a well-balanced diet or supplement their diets with a high-quality omega-3 supplement,” said Alexander.