Calcium Intake Is Inversely Related to Risk of Obesity among American Young Adults over a 30-Year Follow-Up.

BACKGROUND: Calcium (Ca) is an essential nutrient that may play an important role in weight maintenance through its involvement in energy or lipid metabolism. However, little is known about the long-term associations of Ca intake with obesity risk. OBJECTIVES: We aimed to prospectively examine the association between cumulative Ca intake and the incidence of obesity among American young adults over 30 y of follow-up. METHODS: Participants were from the CARDIA (Coronary Artery Risk Development in Young Adults) study. A total of 4097 of 5115 black and white individuals aged 18-30 y at baseline in 1985-1986 were included in the current analysis. Dietary and supplemental Ca intake was assessed by the validated interview-based CARDIA diet history at baseline and exam years 7 and 20. Incident cases of obesity were identified when BMI was ≥30 kg/m2 for the first time since baseline. A survival analysis was performed using Cox proportional hazards regression models to estimate the HRs and corresponding 95% CIs for obesity incidence during follow-up. RESULTS: During a 30-y follow-up (mean ± SD: 20 ± 10 y), 1675 participants developed obesity. Cumulative total Ca intake (dietary plus supplemental Ca) was inversely associated with incidence of obesity in multivariable-adjusted analysis [quintile (Q)5 (highest intake) compared with Q1 (lowest intake): HR: 0.68; 95% CI: 0.56, 0.82; P-trend < 0.01]. This inverse association persisted among Ca supplement users (Q5 compared with Q1: HR: 0.53; 95% CI: 0.40, 0.70; P-trend < 0.01), but was not seen among nonusers. CONCLUSIONS: Following a cohort of Americans from young adulthood to midlife, an inverse association between calcium intake and obesity incidence was observed. Further studies are needed to confirm our findings.