Eating fatty fish and marine omega-3 fatty acids, which are found in fish oil, seem to protect men from heart failure, according to one of the largest studies carried out to investigate this.
However, the effect was only seen in men who ate approximately one serving of fatty fish a week and who had a moderate intake of marine omega-3 fatty acids (approximately 0.3 grams a day). Eating more did not give a greater benefit and, in fact, returned the chances of heart failure to the same level as that seen in men who never consume fatty fish or fish oils.
The study also found that taking food supplements containing marine omega-3 fatty acids did not make made any difference. The men taking part in the study obtained most of the marine omega-3 fatty acids from the food they ate.
Scientists based in the USA and Sweden followed 39,367 Swedish men, aged between 45-79, from 1998 to 2004. Details of the men’s diet and health were recorded and tracked during this time.
The researchers found that men who eat fatty fish, such as herring, mackerel, salmon, whitefish and char, once a week were 12% less likely to develop heart failure compared to men who never eat fatty fish.
The men participating in the study were also divided into five groups according to the amounts of fatty fish and marine omega-3 fatty acids consumed.
The researchers found that the group which ate one serving of fatty fish a week, had a 12% reduced risk of heart failure compared to the men who never eat fatty fish. The men who ate two or three servings of fatty fish a week had a similar risk of heart failure as those who ate none.
Similar results were discovered with marine omega-3 consumption. Men who consumed 0.36 grams a day of fatty acids had a 33% reduced risk of heart failure, whilst men who consumed more had a risk similar to men who consumed none or very little.
Dr Emily Levitan, a cardiology research fellow at Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA, who led the research, said:
“Our study shows that a moderate intake of fatty fish and marine omega-3 fatty acids is associated with lower rates of heart failure in men, but that the men did not gain a greater benefit by eating more of these foods.
The higher rate of heart failure in men who consumed the most fatty fish or marine omega-3 fatty acids compared with moderate consumption may be due to chance.
Alternatively, these may be men in poor health who ate more fish to try to improve their ill-health, and therefore the fatty fish and fatty acids appear to be risk factors for heart failure. I suspect this is the most likely explanation, but we cannot be certain from our data.”
Previous studies have shown that fatty fish and omega-3 fatty acids help to combat risk factors for a range of heart-related conditions such as lowering levels of triglycerides (fats in the blood), blood pressure, heart rate and heart rate variability. This may explain the association with a reduced risk of heart failure found in this study.
Dr Levitan added:
“This study reinforces the current recommendations for moderate consumption of fatty fish. For example, the Swedish National Food Administration recommends consuming fish two to three times per week, with one of those portions being fatty fish.
Similarly, the American Heart Association recommends eating fish, preferably fatty fish, twice a week. Our study supports the idea that a healthy diet, including moderate consumption of fatty fish, can reduce the risk of cardiovascular diseases including heart failure. It will be important to replicate these findings in other populations, particularly those including women, as our study was conducted in men only.”