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, Rajiv Chowdhury, lead study author and a cardiovascular epidemiologist in the Department of Public Health and Primary Care at the University of Cambridge, said in an email.
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 a range of illnesses, including heart attacks, strokes or death.
Current heart association guidelines recommend people consume about two servings of fatty fish each week. They also recommend that 5 percent to 10 percent of total daily calories come from omega-6 sources. The guidelines suggest replacing saturated fats, found in meat, full-fat dairy products and coconut and palm oils with polyunsaturated fats.
Penny Kris-Etherton, a professor of nutrition at Penn State and vice chair of Heart Associations’ Nutrition Committee, said earlier studies may have shown fatty acids aided patients because people with heart disease weren’t being treated as aggressively with cholesterol-lowering medicines and high blood pressure drugs.
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