Fish rich in omega-3 fatty acids may be good for you, but it seems to offer little protection against heart failure, a new study suggests.
The findings, say researchers, do not change the general recommendation that adults aim to eat fish at least twice a week.
Other studies have shown that fatty fish, such as salmon, trout and mackerel, may lower the risk of death from heart disease.
However, heart failure may be a different matter, explained Dr. J. Marianne Geleijnse, the senior researcher on the study and an assistant professor at Wageningen University in the Netherlands.
Heart failure is a chronic condition in which the heart muscle is weakened and cannot pump blood efficiently enough to meet the body's needs — leading to symptoms like fatigue, breathlessness and fluid build-up.
The current thinking, Geleijnse told Reuters Health, is that fish oils act mainly on the heart's electrical activity — preventing deaths by cutting the risk of fatal disturbances in heart rhythm.
She added that evidence suggests the fats have little effect on blood pressure, cholesterol and the build-up of plaque in the heart arteries — important factors in the development of heart failure.
The current study, published in the European Heart Failure Journal, included 5,299 adults age 55 and older who were surveyed about their diets and other health and lifestyle factors. All were free of heart failure at the outset.
Over the next 11 years, 669 study participants developed heart failure. Geleijnse and her colleagues found no relationship between participants' overall fish intake and their risk of the heart condition.
When they looked specifically at consumption of the two main omega-3 fatty acids in fish (EPA and DHA) there was a weak relationship between higher intakes and lower heart failure risk.
That finding, however, was not statistically significant, which means it could have been due to chance.
Regardless, the general recommendation that people eat fish, preferably fatty fish, twice a week "still holds," Geleijnse said.
"The fact that we found only a weak protective association with heart failure...does not mean that eating fish is useless for the prevention of cardiac mortality," she stressed.
The researchers did find some evidence that fish may have specific benefits for people with diabetes.
Among the 479 study participants with diabetes, those with the highest intakes of EPA and DHA from fish were 42 percent less likely to develop heart failure than those with the lowest intakes.
People with diabetes have about twice the risk of heart failure as those without diabetes, Geleijnse pointed out. But it is not clear why fatty fish would be more effective in preventing the heart complication in people with diabetes, the researcher added.
For now, she said, the finding should be considered "hypothesis-generating," and not proof that eating fatty fish wards off heart failure in people with diabetes.
"We recommend that more research is done in diabetics to confirm our findings," Geleijnse said.