Fish intake and cardiovascular risk among middle-aged Japanese in Japan and Brazil

Studies of immigrant populations are useful for analysis of the effects of environmental factors on cardiovascular disease. We have examined the association between dietary habit of fish intake and cardiovascular risk.

Population-based samples of 433 middle-aged Japanese men and women in Japan (Shimane (group JS) and Okinawa (group JO)) and 269 Japanese immigrants in Brazil (Sâo Paulo (group BS) and Campo Grande (group BC)), who had originally moved to Brazil mainly from Shimane and Okinawa, were recruited to the study. They underwent blood pressure measurement, 24-h urine collection, blood tests and electrocardiographic examination, and completed a dietary questionnaire.

There was a significant gradient through the groups, from JS to JO, BS and BC with respect to the prevalence of obesity, hypertension, increased glycohaemoglobin concentrations and ST-T segment change on the electrocardiogram (prevalences for men and women combined: group JS 2.0%, group JO 3.8%, group BS 3.9% and group BC 9.0%; P < 0.025). The prevalence of hypercholesterolaemia was noted more frequently in groups BS and BC. Twenty-four-hour urinary taurine excretion in both sexes and n-3 polyunsaturated fatty acids (n-3 PUFA) in plasma phospholipids in men were significantly higher in groups JS and JO than in groups BS and BC. A striking negative gradient in the frequency of fish intake per week was found from group JS (men/women, 4.7/4.8) to groups JO (3.8/3.6), BS (1.9/1.6) and BC (0.5/0.5).

This study suggests a possible association between fish intake and reduced cardiovascular risk, through the beneficial effects of taurine and n-3 PUFA and a habitual low intake of calories and fat.