Higher adherence to the EAT–lancet diet is associated with reduced risk of metabolic dysfunction–associated steatotic liver disease: a 5-year middle eastern cohort study

Metabolic dysfunction–associated steatotic liver disease (MASLD) is a rapidly increasing metabolic disorder worldwide. Sustainable dietary patterns such as the EAT–Lancet Diet (ELD), designed to promote both human and planetary health, may help prevent MASLD; however, prospective evidence from Middle Eastern populations remains limited. This prospective cohort study included 5,058 Iranian adults aged 20–70 years from the MMRT study who were free of MASLD at baseline. Dietary intake was assessed using a validated 125‑item food frequency questionnaire, and adherence to the ELD was quantified using the Planetary Health Diet Index (PHDI). Incident MASLD over a 5‑year follow‑up was defined using hepatic steatosis (CAP ≥ 238 dB/m) in the presence of metabolic dysfunction. Multivariable logistic regression, restricted cubic splines, and mediation analyses were applied. During follow‑up, 562 participants developed MASLD, yielding a 5-year cumulative incidence of 11.1%. In fully adjusted models, individuals in the third and fourth quartiles of PHDI had 39% (OR 0.61; 95% CI 0.45–0.81) and 34% (OR 0.66; 95% CI 0.50–0.88) lower odds of MASLD, respectively, compared with the lowest quartile (P‑trend < 0.001). Each one‑standard‑deviation increase in PHDI was associated with a 16% lower MASLD risk (OR 0.84; 95% CI 0.76–0.94). The inverse relationship was largely linear, with a suggestive plateau at higher PHDI scores (P for non-linearity = 0.08). Mediation analyses indicated substantial contributions from dietary fiber (71.4%), HOMA‑IR (69.3%), CAP (53.8%), and CRP (44.0%). Greater adherence to a PHDI was associated with lower MASLD risk in Iranian adults, potentially through improvements in insulin resistance, inflammation, hepatic steatosis, and dietary fiber intake.