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Purpose: It has been hypothesized that leptin-induced appetite suppression is impaired in obese individuals, but little human evidence is available documenting this. We investigated relations between serum leptin and total energy intake using INTERLIPID/INTERMAP data on Japanese-Americans in Hawaii and Japanese in Japan. Methods: Serum leptin and nutrient intakes were examined by standardized methods in men and women aged 40-59 years from two population samples, one Japanese-American in Hawaii (88 men, 94 women), the other Japanese in central Japan (123 men, 111 women). Multiple linear regression analyses stratified by BMI category (<25 kg/m, 25-29.9 kg/m, and ≥30 kg/m) with adjustment for possible confounders were used to examine the relation between log-leptin and total dietary energy intake. Results: In multivariate regression analyses, in those with BMI < 25 kg/m and in those with BMI between 25 and 29.9 kg/m, log-leptin was not significantly related to total dietary energy intake; in those with BMI ≥ 30 kg/m, it was significantly inversely related to total dietary energy intake ( P = 0.029), independent of body weight and physical activity. Physical activity score was significantly positively related to total dietary energy intake only in participants with BMI < 25 kg/m ( P < 0.001). Conclusion: Leptin was significantly inversely associated with dietary energy intake in obese persons, but not in overweight and normal-weight persons. [ABSTRACT FROM AUTHOR]

Data from animal studies clearly indicate an association between leptin and hypertension; results of human studies are less concordant. We investigated the role of leptin in obesity-related higher blood pressure (BP) in Japanese Americans living in Hawaii and Japanese in Japan. Serum leptin and BP were examined by standardized methods in men and women ages 40 to 59 years from 2 population samples, one Japanese American in Hawaii (88 men and 94 women) and the other Japanese in central Japan (123 men and 111 women). Multiple linear regression models were used to assess role of leptin in obesity-related higher BP. Across quartiles of leptin, there were significantly higher mean body mass index levels, systolic BP, and diastolic BP for both sexes and sites (P<0.01 to 0.02). In multivariate regression analyses using all of the data combined, relations of body mass index and leptin to systolic BP and diastolic BP remained significant with the interaction term (body mass index x log-leptin) in the models (P<0.01 to <0.05). These findings are consistent with the inference that leptin may be an independent mediator for obesity-related elevations in BP.

Purpose: We sought to identify factors related to total mortality in older Japanese men in Japan and Hawaii., Methods: Baseline data were collected from 1980 to 1982 in 1379 men in Hawaii and 954 men in Japan. Ages ranged from 61 to 81 years, with mortality follow-up during a 19-year period., Results: Compared with Japan, men in Hawaii had a 2-fold excess of diabetes and a 4-fold excess of prevalent coronary heart disease (P < .001). Total cholesterol and body mass index were also greater in Hawaiian men (P < .001). In contrast, men in Japan had greater systolic blood pressure and were nearly 3 times more likely to smoke cigarettes (P < .001). Although each cohort had elements of a poor risk factor profile, there was a 1.4-fold excess in the risk of death in Japan (49.4 vs. 36.2/1,000 person-years, P < .001). Although mortality was similar after risk factor adjustment, only blood pressure and cigarette smoking accounted for the higher risk of death in Japan., Conclusions: Cigarette smoking and hypertension explain much of the excess mortality in Japan versus Hawaii. In this comparison of genetically similar cohorts, evidence further suggests that Japanese in Japan are equally susceptible to develop the same adverse risk factor conditions that exist in Hawaii.

Background: In initial analyses, we found significant differences between serum adiponectin in Japanese living in Japan and Hawaii., Objective: We investigated whether differences in dietary and other lifestyle factors explain higher serum adiponectin concentrations in Japanese in Japan compared with Japanese emigrants living a Western lifestyle in Hawaii., Design: Serum adiponectin and nutrient intakes were examined by standardized methods in men and women aged 40-59 y from 2 population samples, one Japanese American in Hawaii (99 men, 104 women), the other Japanese in central Japan (124 men, 125 women). Multiple linear regression models were used to assess the role of dietary and other lifestyle traits in accounting for serum adiponectin difference between Hawaii and Japan., Results: Mean adiponectin was significantly higher in Japan than in Hawaii (10.5 +/- 5.5 mug/mL compared with 6.7 +/- 3.2 mug/mL in men, P = 0.002; 12.9 +/- 5.9 mug/mL compared with 9.4 +/- 4.2 in women, P < 0.0001). In men, the difference in body mass index (BMI; in kg/m(2)) in the 2 populations explained approximately 90% of the difference in serum adiponectin; in women, only 29%. In multiple linear regression analyses in women further adjustment for physical activity and 4 nutrients (nonvegetable protein, n-3 polyunsaturated fatty acid, arachidonic acid, dietary cholesterol) produced a further reduction in the coefficient for the difference (total 56%); P value for the difference became 0.074., Conclusions: The significantly higher mean serum adiponectin concentration in Japan than in Hawaii may be attributable largely to differences in BMI. Differences in nutrient intake in the 2 samples were associated with only modest relation to the adiponectin difference.