Vitamin D in spine disorders: mechanisms, clinical evidence, and translational gaps—a narrative review

Abstract

Vitamin D has been increasingly implicated in the pathophysiology of spine disorders, yet its clinical utility remains uncertain. Across a broad spectrum of conditions, including intervertebral disc degeneration, chronic low back pain, lumbar spinal stenosis, spinal deformities, and surgical populations, vitamin D deficiency is highly prevalent. Mechanistically, vitamin D exerts pleiotropic effects through the vitamin D receptor, regulating inflammatory signaling, extracellular matrix homeostasis, oxidative stress, and ferroptosis, while also influencing paraspinal muscle biology, and genetic studies suggest that vitamin D receptor polymorphisms may contribute to inter-individual variability in disease susceptibility and cellular response. Despite strong biological plausibility and consistent observational associations, clinical evidence remains heterogeneous. In degenerative and pain-related conditions, randomized trials and meta-analyses do not demonstrate a consistent benefit of supplementation for pain relief or disease modification in unselected populations. In contrast, perioperative spine settings provide more promising findings, with deficiency associated with delayed fusion, poorer functional outcomes, and higher complication risk, while supplementation may improve intermediate-term recovery in selected patients. Across specific conditions such as lumbar spinal stenosis, adolescent idiopathic scoliosis, and axial spondyloarthritis, results remain inconsistent, and current evidence does not support routine supplementation for disease modification. Similarly, although low vitamin D levels are associated with increased risk of osteoporotic vertebral fractures, supplementation has not consistently improved fracture-related outcomes. Overall, vitamin D is best considered a modifiable comorbidity rather than a primary therapeutic target, and a targeted approach focused on deficient or high-risk individuals, particularly in perioperative contexts, appears more appropriate than universal supplementation. Future research should prioritize well-designed trials in deficient populations and precision-based strategies to clarify its role in spine care.