Not all fish products prevent heart disease
The Journal of Family Practice. 2003 June;52(6):431-454
June 1, 2003|Family Medicine
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- BACKGROUND: The protective effect of fish consumption on fatal ischemic heart disease may be related to the effects of omega-3 polyunsaturated fatty acids, which are thought to have an anti-arrhythmic effect. The content of omega-3 fatty acids in fish varies widely, and is an order of magnitude higher in fatty fish (salmon, tuna) than in leaner fish (catfish, cod). Frying may also alter the omega-3 fatty acid content. This study investigated the relationship between consumption of different types of fish and ischemic heart disease risk.
- POPULATION STUDIED: Researchers randomly selected and enrolled 5201 people aged >65 years from 4 US communities in 1989 and 1990. They excluded about 1200 subjects with known ischemic heart disease at baseline, and another 75 who failed to complete the dietary survey, leaving 3910 subjects.
- STUDY DESIGN AND VALIDITY: This was a population-based prospective cohort study. Subjects responded to a picture-sort food frequency questionnaire at baseline to assess usual intake of fried fish/fish burger, tuna fish/salad/casserole, and other broiled or baked fish. Responses were in 5 categories, ranging from <5 times per year to ≥5 times per week.
- OUTCOMES MEASURED: Primary outcomes included total ischemic heart disease death and nonfatal myocardial infarction. Also examined was the subset of ischemic heart disease deaths attributed to arrhythmias.
- RESULTS: The subjects ate an average of 2.2 servings of tuna and other baked/broiled fish and 0.7 servings of fish burgers per week. Consumption of tuna and other baked/broiled fish was associated with a lower risk of death from ischemic heart disease and fatal arrhythmia, but had no effect on the risk of nonfatal myocardial infarction. The risk of death decreased progressively as consumption increased from less than 1 monthly serving to at least 3 weekly servings (hazard ratio=0.47; 95% confidence interval, 0.27–0.82).
PRACTICE RECOMMENDATIONS
For patients aged >65 years, modest consumption of tuna and other broiled/baked fish is associated with a lower risk of death from ischemic heart disease and fatal arrhythmias. The same is not true of fried fish or fish burgers. Instruct patients that not all fish products provide the same health effects.
