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Omega-3s linked with lower risk of fatal heart attacks

Diets rich in foods that contain high levels of omega-3s, such as salmon, may help the heart.Digital Vision/Thinkstock

Omega-3 fatty acids (omega-3s) are a group of molecules that have many important functions in the body. These include blood clotting, muscle activity, digestion, fertility, and brain development.

There are several types of omega-3s, some of which must come from the diet. Eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA) are found in seafood, including fatty fish (such as salmon, tuna, and trout) and shellfish (such as crab, mussels, and oysters). Alpha-linolenic acid (ALA) is found in leafy green vegetables, nuts, and some vegetable oils, such as canola, soybean, and flaxseed. Omega-3s are also available as dietary supplements.

Past research suggests that omega-3s may help protect against heart disease. However, the results have been inconclusive. These variable findings may be because some studies used self-reported dietary information rather than directly measuring omega-3 levels. An international team led by Drs. Dariush Mozaffarian and Liana C. Del Gobbo at Tufts University set out to directly examine the relationship between levels of omega-3s in the body and the onset of heart disease. The research was supported by several NIH components. Results appeared online on June 27, 2016, in JAMA Internal Medicine.

The scientists combined findings from 19 large studies. Together, these included more than 45,000 healthy people from 16 countries (United States, Australia, Costa Rica, Finland, France, Germany, Ireland, Israel, Italy, Norway, Singapore, the Soviet Union, Spain, Sweden, Switzerland, and the United Kingdom). The participants had a median age of 59 years at the start of the studies, and 63% were male.

Blood or tissue levels of several seafood- and plant-derived omega-3s were measured in each study. During a median of 10 years of follow up, almost 8,000 participants developed a first heart attack, including about 7,200 nonfatal heart attacks and 2,800 deaths.

The researchers found that EPA, DPA, DHA, and ALA were all associated with a lower risk of fatal heart disease. DPA was also associated with a lower risk of total heart disease, whereas ALA, EPA, and DHA weren’t. The group didn’t find any associations between omega-3s and nonfatal heart attacks. These relationships held across participant’s age, sex, diabetes status, and use of aspirin or cholesterol-lowering medications.

“Our results lend support to the importance of fish and omega-3 consumption as part of a healthy diet,” Mozaffarian says.

The researchers are conducting further work to understand how omega-3s and other fatty acids in the diet might affect the risk of developing diabetes, obesity, cancers, and other conditions.

—by Carol Torgan, Ph.D.