Red meat consumption, obesity, and the risk of nonalcoholic fatty liver disease among women: Evidence from mediation analysis

Background Previous studies have suggested consumption of red meat may be associated with an increased risk of developing nonalcoholic fatty liver disease (NAFLD). However, large-scale, prospective data regarding red meat consumption in relation to the incidence of NAFLD are lacking, nor is it known whether any association is mediated by obesity. Objective We aimed to evaluate the relationship between red meat consumption and the subsequent risk of developing NAFLD. Design This prospective cohort study included 77,795 women in the Nurses’ Health Study II cohort without NAFLD at baseline (in 1995), who provided detailed, validated information regarding diet, including consumption of red meat, every 4 years, followed through 2015. Lifestyle factors, clinical comorbidities and body mass index (BMI), were updated biennially. Cox proportional hazard models were used to estimate multivariable adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). Results Over 1,444,637 person years of follow-up, we documented 3130 cases of incident NAFLD. Compared to women who consumed ≤1 serving/week of red meat, the multivariable-adjusted HRs of incident NAFLD were 1.20 (95% CI: 0.97, 1.50) for 2–4 servings/week; 1.31 (95% CI: 1.06, 1.61) for 5–6 servings/week; 1.41 (95% CI: 1.13, 1.75) for 1 serving/day; and 1.52 (95% CI: 1.23, 1.89) for ≥2 servings/day. However, after further adjustment for BMI, all associations for red meat, including unprocessed and processed red meat, were attenuated and not statistically significant (all P-trend>0.05). BMI was estimated to mediate 66.1% (95% CI: 41.8%, 84.2%; P < 0.0001) of the association between red meat consumption and NAFLD risk. Conclusions Red meat consumption, including both unprocessed and processed red meat, was associated with significantly increased risk of developing NAFLD. This association was mediated largely by obesity.