Micronutrients in Autoimmune Diseases: Shining a Light on Vitamin D, Cobalamin, Folate, and Iron Metabolism

: Background: Autoimmune diseases (AIDs) are characterized by chronic inflammation and tissue damage resulting from abnormal immune responses. While genetic and environmental factors play significant roles in disease development, essential micronutrient deficiencies (MNDs) represent a critical and often overlooked contributor. Methods: This review examines the interactions between micronutrients and immune cells, focusing on vitamin D, vitamin B12, folate (FA), and iron, and their roles in AIDs, such as rheumatoid arthritis, autoimmune thyroid disorders, multiple sclerosis, systemic lupus erythematosus, and other connective tissue diseases. We explore the immunomodulatory effects of these micronutrients, their impact on immune tolerance, and the mechanisms by which MNDs contribute to disease progression. Results: MNDs are commonly observed in patients with AIDs and are associated with worsening immune dysregulation, increased inflammation, and disease severity. Vitamin D plays a pivotal role in modulating immune responses and attenuating inflammation, while iron and FA are essential for immune cell proliferation and function. Vitamin B12 supports methylation processes and genomic stability. Conclusions: MNDs significantly influence the pathogenesis and progression of AIDs. Routine micronutrient screening and targeted supplementation should be considered as part of clinical management, offering potential adjunctive benefits alongside conventional therapies. Further research is needed to define optimal dosing strategies and to identify patient subgroups most likely to benefit from nutrition-based interventions.