Objective: The objective of our study was to assess nutritional intake in school children (7-9-y-old) and relate calcium intake to body mass index (BMI).
Design: This study was a cross-sectional analysis.
Setting: The data were derived from a community-based survey of children from primary schools of Portugal.
Subjects: In all, 3044 Portuguese children (1503 girls and 1541 boys) from a community-based sample of 7-9-y-olds.
Methods: Height and weight were measured according to international standards, and BMI was calculated. Children's parents completed a self-administered questionnaire that provided information on general family background characteristics and children's physical activity. Children's dietary intake was measured using a 24-h dietary recall. Calcium intake was expressed as the calcium-to-protein ratio, and regression analysis was used to estimate the association between calcium intake and BMI, adjusting for energy intake and confounders.
Results: The prevalence of children with calcium intake below the Dietary Reference Intake was higher in girls (36.4 vs 33.0%, P = 0.053). Calcium-to-protein ratio predicts BMI only in girls (beta = -0.052, P = 0.002), even after adjusting for age, energy intake, parental education, and physical activity.
Conclusion: We found an inverse relationship between calcium intake and BMI only in girls. These data reinforce the need for controlled trials to assess the effects of dietary calcium on body mass in each gender.