Dietary calcium intake and risk of obesity in school girls aged 8-10 years

BACKGROUND Some studies have demonstrated the role of calcium in reducing body mass index (BMI) or fat mass. Though, BMI does not provide very valid information about changes in body fat mass, Fat Mass Index (FMI) relates body fat mass to height and allows comparing body fat mass of individuals at different heights. This study investigated the possible association between dietary calcium intake (CI) and other nutritional factors and weight status of girls aged 8-10 years. MATERIALS AND METHODS In this case-control study, 110 girls aged 8-10 with FMI at or above 7.2 kg/m(2) as cases and 307 girls with FMI less than 7.2 kg/m(2) as controls were recruited through multistage cluster random sampling. FMI at or above 7.2 kg/m(2) was considered as the cutoff point for obesity. Body fat mass was assessed by a stand on bio impedance analyzer. In order to assess CI, participants were asked to complete a validated food frequency questionnaire. RESULTS Mean and standard deviation of CI in the case group was significantly lower than the control group 649 ± 103 and 951 ± 152 mg/d, respectively (P < 0.01). After Adjustment for total energy intake, the percentage of energy from fat, carbohydrate and protein in quartiles of physical activity, inverse association between CI and obesity was significant and in the highest quartile of physical activity the association was weaker. By further adjustment for the effect of fruits and vegetable intake inverse association between CI and obesity became weaker but yet was significant. CONCLUSION The inverse relationship between CI and FMI remained significant even after controlling for confounding factors. FMI may be more accurate, compared to BMI, in showing the association between CI and obesity.