The main vitamin D source is exposure to ultraviolet radiation, which aggravates cutaneous lupus erythematosus (CLE).

The aims of this study were to identify variables associated with lower serum 25-hydroxyvitamin D [25(OH)D] levels in CLE patients and assess the effect of vitamin D restoration on disease severity.

Vitamin D status in 60 CLE patients and 117 apparently healthy subjects was compared. We recommended oral vitamin D3 to 27 CLE patients. After one year of treatment, changes in disease severity were assessed and compared to 25 untreated CLE patients. Disease severity was measured by the Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI), number of exacerbations, duration of active lesions and patient assessment.

Presence of CLE raised the odds of having vitamin D deficiency (OR 3.47, 95% CI 1.79-6.69). Increasing age and disease duration were associated with higher odds of having vitamin D deficiency. After a one-year follow-up, disease activity improved in the treatment group (CLASI A 2.7 ± 2.9 vs. 0.9 ± 1.4) (p = 0.003), as confirmed by the patient assessment (p = 0.01).

Vitamin D inadequacy is more prevalent in CLE participants than in healthy controls. Treating vitamin D insufficiency is associated with improved disease severity according to physician and patient assessments.