Association between dietary fiber intake and bone mineral density: a systematic review and meta-analysis of observational studies

Although prior studies have linked dietary fiber to bone mineral density (BMD), the currently available evidences remain inconsistent and there is a lack of synthesis. This systematic review and meta-analysis aimed to comprehensively examine the association between dietary fiber intake and BMD in adults. We systematically searched the PubMed, Ovid, Web of Science, and ScienceDirect for studies evaluating the association between dietary fiber and BMD, from 2000 to January 2025. Two authors independently extracted data and assessed the risk of bias using the NOS and the AHRQ for observational cohort and cross-sectional Studies. Pooled $$\:\beta\:$$ -coefficients values and their corresponding 95%CIs were calculated using a random-effects model. Subgroup analyses were performed to explore potential sources of heterogeneity. After a systematic search, 6 articles were included involving 7 studies. Meta-analyses included 4 cross-sectional studies with 229,339 individuals, while 2 cohort studies involving 3174 individuals and 1 cross-sectional study involving 9871 individuals were reviewed qualitatively. Overall results indicated that individuals with higher dietary fiber intake exhibited significantly higher BMD levels ( $$\:\beta\:$$ = 0.013, 95%CI = 0.011–0.015, $$\:P$$ < 0.01; $$\:{\tau\:}^{2}$$ = 0.00; $$\:{I}^{2}$$ = 0.00%; $$\:{P}_{Q-test}$$ = 0.86). Leave-one-out sensitivity analyses confirmed the robustness of findings. Subgroup analyses revealed region as the source of heterogeneity. No evidence of publication bias was detected. This study indicates that higher dietary fiber consumption is significantly associated with higher BMD, particularly among males and populations outside Europe and America. Large-scale prospective cohort studies are needed to validate our findings.