Eating foods rich in omega-3 may reduce the risk of death from heart attack, say researchers.
Adopting a healthy diet is considered a key factor in reducing the risk of heart attack, and many studies have suggested that including omega-3 polyunsaturated fatty acids as part of such a diet is particularly beneficial for heart health.
Other studies, however, have questioned the heart benefits of omega-3s, with some suggesting that fish oil supplements - a major source of the fatty acids - do not lower the risk of heart-related events.
Omega-3s are essential fatty acids that the body needs for certain functions, including blood clotting, digestion, muscle activity, and cell division and growth. However, the only way the body can get omega-3 is through the foods we eat.
Fatty fish - such as salmon, trout, tuna, sardines, and anchovies - is a key source of omega-3s, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Other sources include leafy vegetables, walnuts, and some vegetable oils, which normally contain the omega-3 alphalinolenic acid (ALA).
For this latest study, lead researcher Liana C. Del Gobbo, Ph.D., of the Division of Cardiovascular Medicine at Stanford University School of Medicine in California, and colleagues set out to gain a better understanding of how omega-3s affect heart health.
Specifically, they looked at how omega-3s derived from seafood- and plant-based foods influence the risk of death from heart attack, or myocardial infarction.
Risk of fatal heart attack 10 percent lower with higher omega-3 levels
The team analyzed the data of 19 studies that included 45,637 individuals from across 16 countries, including the U.S., the United Kingdom, Italy, Norway, and Australia.
Over time, 7,973 of the participants experienced a first-time heart attack, with 2,781 dying as a result.
The team found that participants who had higher concentrations of seafood- and plant-based omega-3s in their blood were around 10 percent less likely to die from heart attack, compared with participants who had lower omega-3 concentrations.
However, the researchers identified no reduced risk of non-fatal heart attack with higher blood levels of seafood- and plant-based omega-3s, which they say indicates there is a highly specific mechanism by which the fatty acids lower heart attack death risk.
These findings remained after accounting for a number of possible confounding factors, such as participants' age, sex, race/ethnicity, the presence of diabetes, and use of aspirin or cholesterol-lowering drugs.
Overall, the authors say their results indicate that consuming foods rich in omega-3 may lower the risk of non-fatal heart attack.
"At a time when some but not other trials of fish oil supplementation have shown benefits, there is uncertainty about cardiovascular effects of omega-3s. Our results lend support to the importance of fish and omega-3 consumption as part of a healthy diet."
Senior author Dr. Dariush Mozaffarian, Tufts University, Boston, MA