Ultra-Processed Food Consumption and Its Association with Non-Alcoholic Fatty Liver Disease in Iranian Adults: A Case-Control Study

Introduction: Non-alcoholic fatty liver disease (NAFLD) represents a rising global health challenge, marked by excessive fat deposition in the liver. The present case-control study sought to examine the relationship between intake of ultra-processed foods (UPFs) and the risk of NAFLD. Methods: Out of 1000 invited individuals, this case-control study included 225 newly diagnosed NAFLD cases (confirmed via ultrasound) and 450 controls (aged 20–60 years) who underwent ultrasound screening to rule out hepatic steatosis. A validated food frequency questionnaire was used to assess dietary intake, and UPF consumption was quantified both as grams per day and as a percentage of total daily energy intake. Results: The mean (SD) daily UPF consumption amounted to 147.5 (117.4) g, representing 15.4 (7.98)% of total energy intake. After adjusting for potential confounders, UPF intake (kcal/d) showed a positive association with odds of NAFLD (OR=5.91; 95%CI: 2.96–11.78; P for trend<0.001). A one-SD rise in UPF intake (SD=221 kcal/d, roughly equivalent to 117.4 g/d of UPF) was linked to higher NAFLD odds (OR=1.96; 95% CI: 1.63–2.41; P for trend<0.001). When UPF intake was considered as a percentage of energy, the multivariable model revealed elevated NAFLD odds across tertiles (OR=2.27; 95% CI: 1.26–4.10; P for trend<0.001). In the fully adjusted model, each one-SD increment in UPF intake (SD=7.98% of energy/day) was significantly associated with increased odds of NAFLD (OR=1.29; 95%CI: 1.03–1.62; P for trend<0.001). Conclusion: A higher consumption of UPF may be related to increased odds of developing NAFLD.