Vitamin D in patients with psoriasis compared with healthy individuals or with other diseases: A systematic review and meta-analysis

Abstract

Background: Psoriasis is a chronic skin disorder characterized by the accelerated proliferation of keratinocytes, which leads to the formation of scaly plaques and a chronic inflammatory response. Vitamin D is an inhibitor of dendritic cells acting as an immune modulator; therefore, vitamin D deficiency could explain the increased incidence of psoriasis for the reduction of anti-inflammatory activity. Objectives: To compare serum 25-hydroxy vitamin D levels in patients with psoriasis and healthy individuals. Methods: A systematic review of the literature and meta-analysis was performed by searching PubMed, Embase, Cochrane, Lilacs, Ovid and ProQuest databases to find the best available evidence from 2013 to 2024. We also conducted a snowballing literature search to expand the included studies. The methodological quality and risk of bias were assessed through the Newcastle–Ottawa scale. A random effect meta-analysis model was applied. Results: A total of 27 articles were included in the systematic review of these three cross-sectional studies included in the first meta-analysis, the synthesized standardized mean difference (SMD) in serum vitamin D between psoriatic arthritis and psoriasis was −0.13 (95% CI [−0.46, 0.20], p = 0.45). The second meta-analysis included two case controls, the synthesized SMD in serum vitamin D between psoriasis and controls was −0.71 (95% CI [−0.85, −0.57], p = 0.00). Conclusions: No difference in vitamin D levels between psoriasis and psoriatic arthritis was found. Psoriasis patients have lower vitamin D levels than the general population. However, further studies are essential to understand how vitamin D levels contribute to the pathogenesis of psoriasis or vice versa and its role in severity.