Vitamin D Deficiency and Its Association With Disease Activity in Rheumatoid Arthritis

“Rheumatoid arthritis (RA)”is a chronic autoimmune disease characterized by joint inflammation,synovial hyperplasia, and systemic manifestations.Emerging evidence highlights the role of vitamin D not only in bone metabolism but also as an immunomodulator influencing disease activity in RA. This review explores the multifactorial relationship between vitamin D deficiency and RA, focusing on immune pathways, epidemiological trends, disease activity indices, comorbidities, and therapeutic outcomes. Vitamin D modulates key inflammatory responses by affecting T-cell differentiation and cytokine production,thereby influencing the course of RA.Deficiency is highly prevalent among RA patients and correlates with higher disease activity scores,increased joint damage,and reduced bone mineral density. Supplementation has shown promise in reducing disease severity and improving fatigue and comorbid outcomes, although results remain variable across populations. Genetic polymorphisms and epigenetic changes in vitamin D pathway genes may partly explain this variability. Despite ongoing debate, vitamin D assessment and correction represent a low-risk, potentially beneficial adjunct to conventional RA therapies. Future research should aim at optimizing supplementation strategies based on individual patient profiles. The findings underscore the clinical importance of addressing vitamin D status in RA management to improve outcomes and reduce the burden of disease.