The association between serum pinenes and non-alcoholic fatty liver disease based on the NHANES 2013-2014

Terpenes are known to affect metabolic status, though their relationship with non-alcoholic fatty liver disease (NAFLD) remains unclear.

Data from the 2013-2014 National Health and Nutrition Examination Survey (NHANES) were utilized in this cross-sectional study. Serum levels of α-pinene, β-pinene, and limonene were sourced from publicly available data provided by NHANES, determined through gas chromatography-tandem mass spectrometry assays. Participants with a fatty liver index (FLI) score more than 60 were classified as NAFLD. Analytical methods included regression models, mixed-effects models, restricted cubic splines, interaction tests, and mediation analysis.

Among 953 U.S. participants, 444 were diagnosed with NAFLD. The median concentrations of terpenes were 0.09 ng/mL for both α-pinene and β-pinene, and 1.47 ng/mL for limonene. Both single and combined exposure to terpenes were positively associated with NAFLD, with nonlinear associations observed for β-pinene and limonene. Additionally, terpenes were linked to increased levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), with nonlinear relationships noted between β-pinene and ALT and between limonene and both ALT and AST. Notably, ALT and AST levels in participants with NAFLD exhibited increased susceptibility to terpene exposure. As a mediator, NAFLD accounted for approximately 6.9 % and 6.7 % of the indirect effects between α-pinene and limonene with ALT, whereas the direct effects of pinenes on ALT and AST were found to be significant, emphasizing the impact of terpenes on these liver enzymes.

Serum terpene levels were positively correlated with NAFLD, with β-pinene and limonene displaying nonlinear relationships. Additionally, terpene exposure may pose a risk for elevated ALT and AST levels in individuals with NAFLD.