Association between sun exposure, Vitamin D intake, serum Vitamin D level, and immunoglobulin G level in patients with neuromyelitis optica spectrum disorder

Background: Neuromyelitis optica spectrum disorder (NMOSD) is a central nervous system inflammatory disorder in which immunoglobulin G (IgG) autoantibodies possibly play a pathogenic role against the aquaporin‑4 water channel protein. Vitamin D may modulate B‑cell function and decrease the IgG synthesis and may play a role in NMOSD as a crucial factor. The aim of this study was to investigate the relation between Vitamin D intakes from food, Vitamin D intake from sunlight exposure, blood Vitamin D levels, and IgG‑neuromyelitis optica (NMO) level in serum of patients with NMOSD and NMO. Method: In this cross-sectional study, food Frequency Questionnaires (FFQ) and Sun Exposure Questionnaire (SEQ) were completed to evaluate of vitamin D intakes from food and sun light exposure. Moreover, serum levels of 25(OH) vitamin D3 and IgG-NMO were assessed in patients with NMOSD and NMO. Results: We assessed IgG‑NMO levels in 29 patients with NMOSD that nine patients (n = 31%) were positive and for the rest it was negative. Sunlight exposure scale (P = 0.01) and 25(OH) D3 (P = 0.04) in IgG‑NMO‑negative patients were significantly more than patients with positive IgG‑NMO. Age, gender, and latitude were not confounder variables. A positive significant correlation was observed between the sun exposure scale and serum levels of 25(OH) D3 in all participants (r = 0.747, P ≤ 0.001). Conclusions: Physiological variation in Vitamin D may apply a significant effect on IgG‑NMO synthesis in patients with NMO. Vitamin D may have significant role in pathogenesis of NMOSD and NMO.