Associations between dietary calcium intake and lung function were modified by age and gender in the USA : A cross-sectional study of NHANES

Purpose: The present study aimed to evaluate the associations between dietary calcium intake and lung function, and whether these associations were affected by age and gender. Methods A total of 6476 participants aged 18 and above from the National Health and Nutrition Examination Survey (NHANES) of the 2007 to 2012 were included in the analyses. Weighted linear regression was used to estimate beta coefficients and 95% confidence intervals (CIs) for the associations between dietary calcium intake and pulmonary function test parameters, with adjustment for relevant covariates and restricted cubic spline (RCS) analysis were conducted. Results Calcium intake was positively associated with forced expiratory volume in one second (FEV1) (β: 0.16; 95% confidence interval (CI): 0.10–0.21; P < 0.0001) and forced vital capacity (FVC) (β: 0.25; 95% CI: 0.18–0.31; P < 0.0001), and interactions between calcium intake, age, gender, and chronic obstructive pulmonary disease (COPD) existed on lung function. RCS analysis shows that for 60–79 year-old individuals, there was the U-shape dose–response relationship between the calcium intake and FEV1 (P for nonlinearity = 0.0415), and the association between the calcium intake and FEV1 was linear (P for non-linearity = 0.076) for 20–40 years old individuals, and there is no correlation between calcium intake and FEV1 for 40–60 years old individuals (P for overall = 0.8337). In addition, RCS analysis shows that for male, there was the U-shape dose–response relationship between the calcium intake and FEV (P for nonlinearity = 0.0012), while the association between the calcium intake and FVC was linear in female (P for overall = 0.8056). Conclusion Findings suggested that dietary calcium intake and lung function were modified by age and gender. Increased calcium intake was recommended for participants with young and elderly people in improving lung function.