Association of Monounsaturated Fatty Acid Intake with Nonalcoholic Fatty Liver Disease Risk in Chinese Han Adults: a Retrospective Case-control Study

Background While the connection between monounsaturated fatty acid (MUFA) intake and non-alcoholic fatty liver disease (NAFLD) has received attention, research in Chinese populations remains scarce. Objective This study aims to evaluate the association between daily MUFA intake and the prevalence of NAFLD in a Chinese population and to estimate the probable threshold of MUFA intake for NAFLD risk. Methods This case-control study employed data from the Dryad database (https://doi.org/10.5061/dryad.8nn2j46), complying with Dryad's terms of service. We collected data from 534 NAFLD patients and 534 healthy controls who underwent medical tests at the First Hospital of Nanping Affiliated to Fujian Medical University between April 2015 and August 2017. A semi-quantitative food frequency questionnaire (SQFFQ) was used to collect individuals' typical food consumption information, and daily MUFA intake was computed. A thorough analytical technique, including baseline characteristics, multivariate statistics, non-linear relationship analysis, and subgroup research, was applied to study the correlation between daily MUFA intake and NAFLD prevalence. Multiple confounding factors, such as age, sex, lifestyle, and other dietary components, were evaluated to estimate the theoretical threshold of MUFA intake for NAFLD risk. Results In the adjusted model, daily MUFA intake was a significant risk factor for NAFLD (OR=1.04, 95%CI=1.02-1.07, P<0.001). After transforming daily MUFA intake into a categorical variable, the adjusted model demonstrated an increased trend of NAFLD risk with increasing daily MUFA intake (Ptrend<0.001). At 39.04 g/d, non-linear analysis revealed a significant change in the relationship between daily MUFA intake and NAFLD risk. When daily MUFA intake was <39.04 g/d, the risk of NAFLD was 1.08 (95%CI=1.04-1.11, P<0.001). Subgroup analysis revealed significant interactions between sex, age, daily engery intake, and NAFLD risk (Pinteraction<0.05) . Conclusion Increased daily MUFA intake was related to a greater risk of NAFLD, demonstrating a non-linear relationship after a certain threshold (39.04 g/d). This finding shows the need for evaluating both the quality and quantity of dietary fat in NAFLD management.