Across 3 studies, 1 reported a moderate beneficial effect of vitamin D supplementation on reducing Psoriasis Area and Severity Index (PASI) scores, while 2 found neutral small effects. The evidence is mixed, with a predominant neutral effect direction and small effect size. Studies were conducted in clinical psoriasis populations, but dose ranges and forms were not consistently reported.
Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Many of the included studies did not reach statistical significance — effect may be smaller than the predominant direction suggests. The one beneficial study was a systematic review (2025) with a moderate effect, but the two meta-analyses (both 2023) found no significant benefit, highlighting inconsistency.
Adverse events were comparable across interventions (risk ratio 1.02, 95% CI 0.94-1.10).
from: Effectiveness and safety of dietary supplements in the adjunctive treatment of psoriasis:There were no serious adverse effects
from: Efficacy and safety of vitamin D supplementation on psoriasis: A systematic review and metonly a few individuals experienced nausea
from: Efficacy and safety of vitamin D supplementation on psoriasis: A systematic review and metThere were no serious adverse effects
from: Efficacy and safety of vitamin D supplementation on psoriasis: A systematic review and metNo significant differences were found in PASI after 3, 6, and 12 months of supplementation.
vitamin D supplementation significantly reduced PASI scores (mean difference = -3.29, 95% confidence interval [CI] - 6.38 to -0.20)
Pooled analyses showed no significant effect of ... PASI change value (3 months, end of follow-up; P > 0.05).