Foods rich in fish oils such as omega-3 don’t reduce heart-disease risk, calling into question national dietary guidelines that promote the fats as beneficial to cardiovascular health, an analysis of 72 studies found.

The research showed insufficient support for nutritional recommendations by groups such as the American Heart Association that advocate high consumption of polyunsaturated fats like omega-3, found in fish such as salmon, and omega-6, found in corn and sunflower oils, as well as some nuts and seeds. The study appeared in Monday’s Annals of Internal Medicine.

The findings are the latest to show that supplements and vitamins don’t work as well as touted to help patients prevent diseases. While past studies showed fish oil can lower unhealthy blood fats, blood pressure and reduce the risk of a second heart attack, research in recent years contradicted those findings, suggesting it has limited heart benefits.

“The current guidelines should reflect the most recent evidence that show that their apparent benefit for reducing coronary risk is potentially low,” said Rajiv Chowdhury, the lead study author and a cardiovascular epidemiologist in the Department of Public Health and Primary Care at the University of Cambridge in the U.K.

A study presented at the heart association’s 2012 meeting found that taking fish oil, a form of omega-3 fatty acid, after cardiac surgery didn’t prevent a form of irregular heartbeat that can cause blood clots and strokes. Also that year, a review of 20 trials over 24 years published in the Journal of the American Medical Association found that fish oil supplements didn’t lower the risk for heart attacks, strokes or death. A study in 2010 published in JAMA found fish oil didn’t prevent recurrences of atrial fibrillation.

Separate research published Monday in JAMA Internal Medicine found that daily omega-3 supplements weren’t associated with a lower risk for heart attack, stroke or cardiovascular death in older patients with age-related macular degeneration, an eye disease.

Current heart association guidelines recommend people consume about two servings of fatty fish each week, and that 5 percent to 10 percent of total daily calories come from omega-6 sources.

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