Dietary fiber intake, genetic predisposition of gut microbiota, and the risk of metabolic dysfunction-associated steatotic liver disease.

This study aimed to explore the association between dietary fiber intake and the risk of metabolic dysfunction-associated steatotic liver disease (MASLD), as well as liver fat content, while considering genetic predispositions of MASLD, gut microbial abundance, and butyrate levels. This study analyzed data from 190,276 participants in the UK Biobank. Dietary fiber intake was assessed using 24-h dietary recall. MASLD cases were diagnosed through hospital admission records and death registries, and liver fat content was measured via magnetic resonance imaging. The genetic predispositions of MASLD, gut microbial abundance, and butyrate levels were evaluated using single nucleotide polymorphisms. Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95 % confidence intervals (CIs). Over a median follow-up of 10.49 years, 1423 MASLD cases were recorded. Elevated dietary fiber intake was associated with a reduced risk of MASLD (HR: 0.72; 95 % CI: 0.58, 0.90) and a lower level of liver fat content (β: -0.97; 95 % CI: -1.21, -0.73) (all P for trend <0.05). Restricted cubic spline analyses further confirmed the linear inverse associations between fiber intake and the risk of MASLD. Notably, the negative associations between dietary fiber intake and both MASLD and liver fat content were consistent across different genetic predispositions of gut microbial abundance and butyrate levels. Moreover, the inverse association between dietary fiber intake and liver fat was strengthened by high genetic susceptibility of MASLD and elevated body mass index (both P for interaction <0.05). Overall, increased dietary fiber consumption was associated with a lower MASLD risk and decreased liver fat content regardless of genetic predispositions of gut microbial abundance and butyrate levels.