Association of dietary fiber sources with liver fibrosis assessed by transient elastography in U.S. adults: a cross-sectional study from NHANES 2017 to 2020

Dietary fiber intake is linked to metabolic health, yet its association with liver fibrosis, particularly across different fiber sources, remains incompletely understood. This study aims to assess the relationship between dietary fiber from various sources and liver fibrosis in Unites States National Health And Nutrition Examination Survey adults. We used data from National Health and Nutrition Examination Survey 2017 to 2020, examining the associations between dietary fiber intake and liver fibrosis assessed by transient elastography in a nationally representative sample of United States adults. Dietary fiber intake, including total fiber and fiber from fruits, vegetables, grains, and legumes, was assessed using 24-hour dietary recalls. Liver fibrosis was evaluated using both continuous liver stiffness measurements and a categorical definition of significant fibrosis (median liver stiffness ≥ 8 kPa). Survey-weighted linear and logistic regression models were applied, adjusting for sociodemographic characteristics, lifestyle behaviors, metabolic comorbidities, and total energy intake. After multivariable adjustment, higher intake of fruit-derived dietary fiber was consistently associated with lower liver stiffness (β = -0.13, 95% confidence interval: -0.22 to -0.04). Compared with the lowest quartile, participants in the highest quartile of fruit fiber intake had significantly lower odds of significant liver fibrosis (odds ratio = 0.61, 95% confidence interval: 0.45-0.83). In contrast, total dietary fiber and fiber from vegetables, grains, and legumes showed weaker or less consistent associations, and no clear monotonic dose-response relationships were observed. These findings suggest that the source of dietary fiber, particularly fruit-derived fiber, may be more relevant than total fiber intake alone in relation to liver fibrosis risk. This study emphasizes the clinical importance of fiber sources in liver fibrosis management and supports further prospective studies to clarify causality.