Large differences in serum leptin levels between nonwesternized and westernized populations: The Kitava study

Abstract

Objectives. To compare serum leptin between non-westernized and westernized populations. Setting. (i) The tropical island of Kitava, Trobriand Islands, Papua New Guinea and (ii) the Northern Sweden MONICA study population. Design. Cross-sectional survey. Methods. Fasting levels of serum leptin were analysed in 163 randomly selected Kitavans aged 20-86 years and in 224 Swedes aged 25-74. Main outcome measures. Mean and determinants of serum leptin. Results. Geometric mean of serum leptin in Kitavan males and females were 1.5 and 4.0 vs. 4.9 and 13.8 ng mL-1 in Swedish male and females (P < 0.0001 for both sexes). In Kitavans, observed geometric mean were close to predicted levels (1.8 ng mL-1 for males and 4.5 ng mL-1 for females) based on multiple linear regression equations including body mass index (BMI), triceps skinfolds (TSF) and age from the Swedish population-based sample. In Kitavans serum leptin was positively related to TSF amongst both sexes and, amongst females, to BMI. In Kitavans leptin was not related to fasting serum insulin. TSF explained 55% of the variation of leptin amongst females. There was a slight age-related increase of leptin amongst males. In Kitava leptin was not related to fasting serum insulin which was substantially lower than in Sweden. Conclusion. The low concentrations of serum leptin amongst Kitavans probably relates to the absence of overweight and hyperinsulinaemia. At a population level serum leptin can apparently be predicted from simple measures of adiposity.