[Cross-sectional association between dietary zinc intake and phalangeal osteoporosis]

To examine the association between dietary zinc intake and phalangeal osteoporosis.
 Methods: The subjects of this study were members aged over 40 years or above of the general population who had undergone routine health examinations at Xiangya Hospital, Central South University in Changsha, Hunan, China, between October 2013 and December 2015. Dietary zinc intake was measured using the semi-quantitative food frequency questionnaire. Phalangeal osteoporosis was diagnosed according to the WHO criteria based on the assessment of bone mineral density. According to the quartile distribution, serum zinc concentrations were classified into categories: Q1≤15.40 mg/d, Q2 15.41-18.67 mg/d, Q3 18.68-22.76 mg/d, and Q4≥22.77 mg/d. The association between dietary zinc intake with phalangeal osteoporosis was evaluated by conducting multivariable adjusted logistic regression. The dose-response relationship between them was assessed by restricted cubic spline regression.
 Results: A total of 6 267 subjects were included, 602 (9.6%) among them were suffered from phalangeal osteoporosis. The multivariable-adjusted models (i.e. Model 2 and 3) showed that, compared with the lowest quartile, the odds ratios (ORs) for phalangeal osteoporosis were lower in the second, third and fourth quartiles of dietary zinc intake (Model 2: P for trend = 0.045; Model 3: P for trend = 0.031) in the total population; the ORs for phalangeal osteoporosis were lower in the third and fourth quartiles of dietary zinc intake (Model 2 and 3: P for trend = 0.018) in the male population; and the ORs for phalangeal osteoporosis were lower in the second, third and fourth dietary zinc intake quartiles (Model 2: P for trend = 0.227; Model 3: P for trend = 0.217) in the female population. There also existed dose-response relationship between dietary zinc intake and the prevalence of phalangeal osteoporosis (P<0.001).
 Conclusion: Dietary zinc intake is negatively associated with phalangeal osteoporosis in the total population and male subgroup, but not female subgroup.