Eating salmon or other fatty fish just once a week helped reduce men's risk of heart failure, a study shows, adding to growing evidence that omega-3 fatty acids are of benefit to cardiac health. Led by researchers at Boston's Beth Israel Deaconess Medical Center and reported in an online issue of the European Heart Journal, the findings represent one of the largest studies to investigate the association between fish consumption and heart health.

"Previous research has demonstrated that fatty fish and omega-3 fatty acids help to combat risk factors for a range of heart-related conditions, such as lowering triglycerides (fats in the blood) and reducing blood pressure, heart rate, and heart rate variability," says study co-author Emily Levitan, a research fellow in Beth Israel's Cardiovascular Epidemiology Research Center. "Collectively, this may explain the association with the reduced risk of heart failure found in our study."

Congestive heart failure usually is caused by cardiac conditions such as high blood pressure and coronary-artery disease. Heart failure is the leading cause of hospitalization among patients 65 and older and is characterized by such symptoms as fatigue and weakness, difficulty walking, rapid or irregular heartbeat, and persistent cough or wheezing.

The researchers followed more than 39,000 Swedish men between the ages of 45 and 79 from 1998 to 2004. The researchers recorded details of the men's diet and tracked the men's outcome through Swedish inpatient hospital registers and cause-of-death registers.

Analysis of their numbers showed that the men who ate fatty fish (herring, mackerel, salmon, whitefish, and char) once a week were 12 percent less likely to suffer heart failure, compared with men who ate no fatty fish.

Although this association did not reach statistical significance, the researchers also found a statistically significant association with the intake of marine omega-3 fatty acids, which are found in cod liver and other fish oils. The men who consumed approximately 0.36 grams a day were 33 percent less likely to develop heart failure than the men who consumed little or no marine omega-3 fatty acids.

"We divided the men into five groups based on their intake of fatty fish," Levitan says. "The first group consumed little or no fatty fish; at the other end of the spectrum, the fifth group consumed significant quantities, three or more servings per week. We found that while the 'middle group'—whose members ate one serving per week—had a 12 percent reduced risk of heart failure, the next two groups, whose members ate either two servings a week or three or more servings a week, had nearly the same heart failure risk as the men who ate no fish at all."