High-quality diet, physical activity, and college education are associated with low risk of NAFLD among the US population

Background and aims: The effects of diet quality (DQ), physical activity (PA), and socioeconomic status (SES) on the risk of NAFLD are unclear. We examined the association among DQ, PA, SES, and NAFLD risk.

Approach and results: This is a cross-sectional analysis of the National Health and Nutrition Examination Surveys, 2017-2018, which included 3589 participants with reliable information on vibration-controlled transient elastography (VCTE) measurements, 24-h dietary recalls, PA, and SES. DQ was assessed by the Healthy Eating Index (HEI)-2015. PA was determined by the Global Physical Activity Questionnaire. SES was assessed by the educational attainment and family poverty income ratio (PIR). Risk of NAFLD was considered by means of a composite outcome using VCTE measurements: non-NAFLD versus NAFLD without clinically significant fibrosis (CSF) versus NAFLD with CSF. The NAFLD risk was lower in physically active (≥600 metabolic equivalent of task [MET] min/week) versus inactive participants (<600 MET min/week) (OR: 0.71, p = 0.043). A high-quality diet (HQD) (HEI > 56.64) was associated with a lower risk of NAFLD (OR: 0.58, p < 0.01) compared with a non-HQD. The lowest NAFLD risk was observed in those physically active with HQD (OR: 0.43, p < 0.01). Body mass index and waist circumference significantly mediated the effect of DQ and PA on NAFLD risk. Education (college or above) (OR: 0.65, p = 0.034), but not PIR, was associated with a reduced NAFLD risk. HQD and increased PA partially mediated the effect of education on NAFLD risk. The total effect of education on NAFLD risk mediated by DQ was 29% and by PA was 8%.

Conclusions: HQD, increased physical activity, and college education were associated with lower NAFLD risk in the US population.