CHICAGO --- A new look at a famous Chicago study on nutrition and heart disease further documents that men who ate a moderate amount of fish had a lower risk for dying of a heart attack than men who did not eat fish.
Results of the 30-year follow-up Western Electric study, conducted by researchers at Northwestern University Medical School, were published in the April 10 issue of the New England Journal of Medicine.
The study found that the death rate from heart attack was lower in men who ate about 35 grams of fish per day than in men who did not eat fish. This finding held true after accounting for differences in age, cigarette smoking, serum cholesterol level and blood pressure, as well as for obesity, education, alcohol consumption, calorie intake and many other dietary and demographic factors.
"Baseline fish consumption was independently, significantly and inversely related to fatal myocardial infarction [heart attack], especially the non-sudden kind where death occurs after three hours," said Martha Daviglus, M.D., assistant professor of preventive medicine and lead researcher on the Northwestern study.
"Data from this, and many other observational studies, indicate that eating small amounts of fish, even lean fish, is associated with a lower risk for heart attacks," she said.
Daviglus emphasized that the men in the Western Electric study ate only about one or two servings of fish per week (7 ounces), an amount than can easily be worked into most people's diet.
These findings support those from most other studies that also indicate cardiovascular health benefits of eating fish. However, there have been a few studies that did not find a relationship between eating fish and heart disease. The Northwestern researchers believe these apparent inconsistencies probably are due to several differences in the study populations and methods used to determine fish consumption.
The study, initiated in 1957 by Chicago cardiologist Oglesby Paul, M.D., and continued by internationally renowned preventive cardiologist Jeremiah Stamler, M.D., emeritus professor of preventive medicine at Northwestern, focused on 1,800 men who were employed at the Hawthorne Works of the Western Electric Company in Cicero, Ill.
Participants were 40 to 55 years old, 68 percent blue collar and 47 percent Catholic. On average, the group was overweight and had above-desirable blood pressure and serum cholesterol levels. Information on food consumption was collected using two extensive diet histories, administered in 1958 and 1959, including a dietary questionnaire on amounts of fish and other foods usually consumed.
Other cardiovascular risk factors, such as cigarette smoking, blood pressure, serum cholesterol level and height and weight, also were measured. The amount of fish consumed was then related to 30-year risk of death from coronary heart disease, sudden and non- sudden heart attack and death from other causes.
Daviglus said the study did not examine the type of fish eaten, and the findings are for men, since women were not part of this study. She also said that results of this study support the view that eating fish protects against heart attack, but further research is needed, particularly intervention trials that can test this definitively. In addition, further studies also are needed as to possible mechanisms.
"It could relate to the effect fish has on cell membranes, serum triglycerides, or the specific type of protein or fat in the fish," she said. "The good news is that small amounts of fish, amounts all of us can easily fit into our diets, may make a difference."
Other researchers on this study were Philip Greenland, M.D., Harry W. Dingman Professor and chair of preventive medicine; Alan R. Dyer, professor of preventive medicine; Kiang Liu, professor of preventive medicine; Molly K. Walsh, research associate; and Douglas Morris, senior programmer, of Northwestern University Medical School; Anthony J. Orencia, M.D., of the Indiana University School of Medicine, Indianapolis; and Richard B. Shekelle of the University of Texas Health Sciences Center, Houston.
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