Dietary zinc intake, supplemental zinc intake and serum zinc levels and the prevalence of kidney stones in adults

Objective: The association between zinc intake and the risk of kidney stones remains controversial. We examined the associations between dietary zinc intake, supplemental zinc intake and serum zinc levels and the prevalence of kidney stones in adults. Methods: Adult participants from the 2007-2016 NHANES were included. Restricted cubic splines were adopted to assess the dose-response relationships. Results: Dietary zinc intake was linearly associated with the prevalence of kidney stones (Pfor non-linearity = 0.50), and the odds ratios (95% confidence intervals) of kidney stones were 0.75 (0.51-1.04) for 10 mg/day, 0.65 (0.39-0.97) for 20 mg/day, 0.53 (0.30-0.94) for 30 mg/day and 0.45 (0.22-0.95) for 40 mg/day. The linear relationship was also observed among women and overweight/obese individuals. No association was found between supplemental zinc intake and the prevalence of kidney stones. A non-linear relationship was found between serum zinc levels and the prevalence of kidney stones (Pfor non-linearity = 0.02), and the odds ratios (95% confidence intervals) of kidney stones were 0.52 (0.33-0.82) for 70 ug/dL, 0.43 (0.24-0.77) for 90 ug/dL, 0.56 (0.32-0.98) for 110 ug/dL and 0.77 (0.37-1.62) for 130 ug/dL. The non-linear relationship was also observed among men and overweight/obese individuals. Conclusions: Dietary zinc intake and serum zinc levels were inversely associated with the prevalence of kidney stones in adults, and there may be effect modification by participant sex and body mass index. The present analysis is limited in its ability to establish causality.