Introduction

What makes fish such an essential part of a "heart healthy" diet? Part of the answer is that they contain omega-3 fatty acids, a type of fat found in fish (especially "cold water" varieties like salmon, mackerel, sardines, and tuna), as well as flax seed, canola oil, soybean oil, and some kinds of nuts.

Studies show that a steady diet of foods high in omega-3 fatty acids appears to reduce the risk of heart disease and stroke. Researchers think that these fats may work by reducing the "stickiness" of blood cells, making them less likely to clump together and block arteries. An article in the Journal of the American Medical Association adds to our understanding of the health benefits of this kind of fat.

Study results

Harvard researchers assessed the diets and health habits of almost 80,000 middle-aged American women. They then kept track of them for the next 14 years and noted which women suffered a stroke during that time. After accounting for factors like age, smoking, and body weight that can affect stroke risk, the researchers found that those who ate fish at least two to four times a week were about half as likely to suffer a stroke when compared to others in the study.

The researchers then wanted to know whether a diet that contains high levels of omega-3 fatty acids would be "too much" of a good thing? Their concern arose from studies of Greenland Eskimos, who eat a fish-based diet and are at greater-than-average risk of hemorrhagic stroke, a type of stroke caused by a ruptured blood vessel in the brain. But data from the current study showed that even women who regularly consumed fish five or more times per week were no more likely to suffer from hemorrhagic stroke than those who rarely ate fish. They conclude that since the American diet includes so many different kinds of foods, it is not likely that Americans can consume unhealthy amounts omega-3 fatty acids.

Diet advice

Although this study included only women, similar results have been found in men. This has prompted the American Heart Association to recommend at least 2 servings of fish a week as part of a heart healthy diet.

** Warning: It is possible to consume too much omega-3 fatty acids that have been concentrated into supplement form, commonly as fish oil capsules. Consumers should always check with their healthcare provider before they bypass foods high in omega-3 fatty acids in favor of fish oil supplements.