Associations Between Serum Zinc Levels and Alanine Aminotransferase Elevation in Adults

Recent findings showed that zinc might be linked to alanine aminotransferase (ALT) elevation. This analysis aimed to explore the association between serum zinc levels and ALT elevation in adults. Data on serum zinc and ALT levels from adults aged 20 years and older who participated in the 2011-2016 National Health and Nutrition Examination Surveys were analyzed (N = 4138). Individuals with excessive alcohol consumption and hepatitis B or C infection were excluded. ALT elevation was defined as any value above normal of ALT (> 33 IU/L for males and > 25 IU/L for females). The multivariate logistic model and restricted cubic splines were adopted to assess the non-linear relationship. In a fully adjusted model, the odds ratio and 95% confidence interval of ALT elevation for quartile 4 (Q4) vs. quartile 1 (Q1) of serum zinc levels were 1.68 and 1.29-2.20 (per quartile: 1.20 (1.10-1.31)). In subgroup analysis, the association between serum zinc levels and ALT elevation was found in females (Q4 vs Q1: 1.95 (1.20-3.15)), obese individuals (Q4 vs Q1: 1.80 (1.19-2.74)), and young adults (Q4 vs Q1: 1.72 (1.09-2.72)), while the association was not evident in males, non-obese individuals, and adults older than 50 years old. A linear dose-response relationship between serum zinc levels and ALT elevation was found (P_{for non-linearity} = 0.77). In conclusion, serum zinc was positively associated with ALT elevation in adults, and the association was mainly observed in females, obese individuals, and young adults.