Fish-rich diet, leptin, and body mass.

BACKGROUND Leptin has been implicated in cardiovascular disease. A diet rich in fish has been associated with decreased cardiac and vascular risk. METHODS AND RESULTS We examined the relationship between diet and leptin in 2 related homogeneous African tribal populations of Tanzania. One tribe consumes freshwater fish as their main diet component (n=279), and the other tribe consumes a primarily vegetarian diet (n=329). In multivariate analysis, plasma leptin levels were associated with type of diet (F=14.3, P<0.001), independent of age, body mass index, body fat, alcohol consumption, or insulin. Both male (2.5+/-2 [fish diet] versus 11.2+/-2.4 [vegetarian diet] ng/mL, P=0.017) and female (5.0+/-1.9 [fish diet] versus 11.8+/-1.4 [vegetarian diet] ng/mL, P=0.007) fish eaters had lower plasma leptin levels than did their vegetable diet counterparts, even though body mass index values were virtually identical. CONCLUSIONS A diet rich in fish is associated with lower plasma leptin, independent of body fat. These findings may have implications for understanding the reduced cardiovascular risk in subjects on a high-fish diet.