The study, called the Spanish EPIC (European Prospective Investigation into Cancer and Nutrition) Cohort Study, followed more than 40,000 men and women ages 20 to 69 for an average of 10.4 years. Researchers used medical records and autopsy reports to identify those who had developed CHD—some 609 men (there were not enough women with CHD to analyze findings). Then they compared the intake of fatty fish (and the two important fatty acids in that fish, EPA and DHA) between the people who developed CHD and those who didn’t. They found no difference in intake between the two groups, leading them to conclude that eating fatty fish does not prevent CHD. But the study, published in the journal Nutrition, Metabolism & Cardiovascular Disease, has some significant shortcomings that undermine its conclusions, says Duffy MacKay, a naturopathic doctor and senior vice-president for scientific and regulatory affairs with the Council for Responsible Nutrition. The first weakness of this study is that fish intake was determined from a single dietary recall questionnaire done at the beginning of the study, which asked people to recall how often they ate a variety of foods within the past few days or weeks. Although these questionnaires are routinely used, they’re not particularly accurate, especially when a single questionnaire is used in a 10-year study, MacKay says. Testing for blood levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is a better way to determine someone’s status with regard to these fatty acids. Another problem is that the Mediterranean population in the study had a uniformly high intake of fatty fish, and a low incidence of heart disease, which may partly explain the lack of association between CHD and fish intake, which the study authors themselves point out. “Even the men in the lowest intake group got more than what is considered to be the minimum effective dose (250 mg a day of EPA and DHA) required for protection from cardiovascular disease,” they say. The average intake of combined EPA/DHA for both men with and without CHD was 600 mg a day. That means both groups were equally protected. “Fish oil protection doesn’t continue to increase the more and more fish oil you take,” MacKay explains. “Once you reach a threshold—an amount found to offer cardiovascular protection—the benefits level off," MacKay says. Where you might have seen a difference is if you compared the Spanish population to people in the U.S., where the average intake of combined EPA/DHA in the U.S. is 68 mg a day, according to NHANES nationwide dietary survey. That is well below amounts shown to provide heart benefits. “If we were to fill in this gap, making sure everyone got at least 250 mg a day of fish oil, we would likely see a reduction in heart disease,” MacKay says. Bottom line: Keep eating fatty fish. Opt for wild-caught salmon (farmed salmon doesn’t have enough EPA and DHA) sardines, anchovies, mackerel, herring, lake trout, and albacore tuna. Avoid fried fish, tilapia, and other “farmed” fish. If you don’t eat fish, consider taking fish oil (or algae supplements if you’re vegetarian) to get the equivalent amounts. More from Prevention: The Supplement That Could Extend Your Life 18%
