Inverse association of marijuana use with nonalcoholic fatty liver disease among adults in the United States

Background & aims The impact of marijuana on nonalcoholic fatty liver disease (NAFLD) is largely unknown. We studied the association between marijuana and NAFLD utilizing cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) from 2005–2014 and NHANES III (1988–1994). Methods Suspected NAFLD was diagnosed if serum alanine aminotransferase (ALT) was > 30 IU/L for men and > 19 IU/L for women in the absence of other liver diseases (NHANES 2005–2014). In NHANES III cohort, NAFLD was defined based on ultrasonography. Results Of the 14,080 (NHANES 2005–2014) and 8,286 (NHANES III) participants, prevalence of suspected NAFLD and ultrasonographically-diagnosed NAFLD were inversely associated with marijuana use (p < 0.001). Compared to marijuana-naïve participants, marijuana users were less likely to have suspected NAFLD (odds ratio [OR]: 0.90, 95% confidence interval [CI]: 0.82–0.99 for past user; OR: 0.68, 95% CI: 0.58–0.80 for current user) and ultrasonographically-diagnosed NAFLD (OR: 0.75, 95% CI: 0.57–0.98 for current user) in the age, gender, ethnicity-adjusted model. On multivariate analysis, the ORs for suspected NAFLD comparing current light or heavy users to non-users were 0.76 (95% CI 0.58–0.98) and 0.70 (95% CI 0.56–0.89), respectively ( P for trend = 0.001) with similar trends in ultrasonographically-diagnosed NAFLD (OR: 0.77, 95% CI: 0.59–1.00 for current user; OR: 0.71, 95% CI: 0.51–0.97 for current light user). In insulin resistance-adjusted model, marijuana use remained an independent predictor of lower risk of suspected NAFLD. Conclusions In this nationally representative sample, active marijuana use provided a protective effect against NAFLD independent of known metabolic risk factors. The pathophysiology is unclear and warrants further investigation.