Regulatory T (Tregs) cells play an important role in the maintenance of immunological
tolerance. It decrease in the peripheral blood of rheumatoid arthritis patients. Vitamin D
has an immunomodulatory and anti-inflammatory effect in rheumatoid arthritis.
Vitamin D supplementation significantly enhances Tregs percentage in the peripheral blood of
RA patients. So supplementation of Vit D improves rheumatoid arthritis disease activity.