Association between dietary fiber intake and total bone mineral density in adolescents: A cross-sectional analysis of the NHANES 2011–2018

Objective Adolescence is a critical window for optimizing peak bone mass. This study evaluated the independent association between dietary fiber intake and total body bone mineral density (BMD) in a representative sample of U.S. adolescents. Methods This cross-sectional study analyzed 2476 participants (aged 12–19 years) from the National Health and Nutrition Examination Survey 2011–2018. Dietary fiber intake was calculated as the average of two 24-h recalls. Total BMD was measured using dual-energy X-ray absorptiometry. Multivariable linear regression, generalized additive models, and stratified analyses were utilized, adjusting for sociodemographics, body mass index (BMI), physical activity, renal function markers (creatinine, blood urea nitrogen), and dietary variables (calcium, vitamin C, and energy intake). Results Dietary fiber intake was positively associated with total BMD in the fully adjusted model (β = 0.001 g/cm 2 , 95% CI: 0.001–0.002; p = 0.029). Compared to the lowest tertile (T1), the highest tertile (T3) exhibited significantly higher BMD (β = 0.016 g/cm 2 , 95% CI: 0.001–0.031; p = 0.038; p for trend = 0.039). Generalized additive models confirmed a stable linear relationship (effective degrees of freedom = 1.0, p for nonlinearity = 0.158). Significant interactions were identified for gender, age, race, and BMI ( p for interaction < 0.05), with the association being most pronounced among Non-Hispanic White participants and those in the medium-BMI tertile. Conversely, no significant interactions were observed for poverty–income ratio and physical activity ( p for interaction > 0.05). Conclusions Higher dietary fiber intake is independently associated with increased total body BMD in U.S. adolescents. Optimizing fiber consumption may be a strategic approach for enhancing bone mass accrual, particularly among those with a healthy body weight.