The Gut-Lumbar Axis: A Comprehensive Review of Mechanisms, Clinical Evidence, and Future Therapeutic Perspectives.

Low back pain (LBP) affects approximately 619 million people globally and is the leading cause of years lived with disability, yet the pathogenesis of chronic LBP remains incompletely understood despite extensive research into structural and biomechanical factors. Emerging evidence suggests that the gut microbiota, through its influence on systemic inflammation, immune regulation, metabolic homeostasis, and neuromodulation, plays a previously unrecognized role in lumbar spine pathology. While prior frameworks such as the "gut-disc axis" and "gut-spine axis" have addressed intervertebral disc degeneration or vertebral bone metabolism in relative isolation, we propose the "gut-lumbar axis" as an integrative framework that systematically unifies the intervertebral discs, vertebrae, paraspinal musculature, and neural structures of the lumbar spine within a single physiological and pathological continuum. This review synthesizes current evidence on the bidirectional communication between intestinal microbiota and lumbar spine health, covering intervertebral disc degeneration, chronic LBP, lumbar spinal stenosis, and vertebral osteoporosis. Multiple pathways linking gut dysbiosis to lumbar pathology are identified, supporting the gut-lumbar axis as a paradigm-shifting framework. However, large-scale longitudinal cohorts and well-designed randomized controlled trials are urgently needed to translate these findings into clinical practice. Microbiome-targeted therapies, including probiotics, dietary interventions, and fecal microbiota transplantation, hold promise as novel adjunctive strategies for managing chronic lumbar spine disorders, and key knowledge gaps for future investigation are highlighted.