Vitamin D has important immunomodulatory effects, but there is no direct evidence that it increases serum 25-hydroxylated vitamin D (25(OH)D) levels in patients with juvenile-onset systemic lupus erythematosus (SLE). To assess the effect of vitamin D supplementation on disease activity and fatigue symptoms in patients with juvenile-onset SLE, Dr. Lima et al. in Brazil conducted a randomized, double-blind, placebo-controlled trial, the results of which were published in a recent ACR. The 24-week trial included 40 patients with juvenile-onset SLE, randomized in a 1:1 ratio, with the VitD group receiving 50,000 IU/week of oral cholecalciferol (vitamin D3) and the placebo group receiving placebo accordingly. The medication was kept stable throughout the study period. Serum 25(OH)D levels were measured by radioimmunoassay, and disease activity was assessed using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and the European Criteria for Lupus Activity (ECLAM). Fatigue was assessed using the Fatigue Severity Scale for Children. At baseline, age, body mass index, lesion involvement in organs, glucocorticoid dose, use of immunosuppressive drugs, SLEDAI, ECLAM, K-FSS and 25(OH)D levels were similar in both groups. at 24 weeks, mean serum 25(OH)D levels were higher in the vitamin D group compared to the placebo group. At the end of the intervention, both SLEDAI and ECLAM were significantly improved in the vitamin D group compared to the placebo group. As for the level of fatigue, there was a decrease in fatigue related to social life score in the vitamin D group relative to the placebo group. In addition, cholecalciferol was well tolerated with no serious adverse events. This study suggests that 24 weeks of cholestyramine supplementation may reduce disease activity and improve fatigue in patients with juvenile-onset SLE. Summary of key points: 1. This is the first study of vitamin D supplementation in juvenile-onset SLE. 2. In 70% of patients with juvenile-onset SLE, cholestyramine supplementation (50,000 IU/week) for 6 months resulted in adequate serum 25-hydroxyvitamin D levels. Supplementation with cholecalciferol (50,000 IU/week) for 6 months was effective in reducing disease activity in patients with juvenile-onset SLE. Supplementation with cholecalciferol (50,000 IU/week) for 6 months was associated with improvement in fatigue symptoms in patients with juvenile-onset SLE.