Vitamin D supplementation exerts no effect on psoriasis severity in vitamin D-deficient individuals

Supplementation with vitamin D falls short of reducing psoriasis severity for individuals with 25-hydroxyvitamin D (25[OH]D) levels of <24 ng/mL, as reported in a study.

The study included 122 individuals (mean age 53.6 years, 37.7 percent women, mean Psoriasis Area Severity Index [PASI] score 3.1) from the general population in Tromsø, Norway, with active plaque psoriasis mean serum 25(OH)D of 14.9 ng/mL. These participants were randomly assigned to receive vitamin D (n=60; cholecalciferol 100,000 IU loading dose, followed by 20000 IU/week) or placebo (n=62) for 4 months.

A total of 120 participants completed the study, with mean 25(OH)D levels being higher in the vitamin D group than in the placebo group by the end of treatment (29.7 vs 12.0 ng/mL). However, the change in PASI score did not significantly differ between the two groups (adjusted difference, 0.11, 95 percent confidence interval [CI], −0.23 to 0.45).

Likewise, there were no significant between-group differences seen in the change in Physician Global Assessment score (adjusted odds ratio, 0.66, 95 percent CI, 0.27–1.63), self-administered PASI (adjusted difference, −0.60, 95 percent CI, −1.76 to 0.55), and Dermatology Life Quality Index (adjusted difference, −0.86, 95 percent CI, −1.9 to 0.19). No adverse effects of the intervention were documented.

The lack of measurable effect might be explained by low baseline severity scores and a less-than-expected degree of increase in levels of 25(OH)D in the intervention group based on previous experimental data from the same source population.