Does vitamin D supplementation affect psoriasis severity?

Topical vitamin D analogues are routinely used as a psoriasis treatment, but the effect of oral supplementation has yet to be established. Considering this, Marita Jenssen, University Hospital of North Norway, Tromsø, Norway, and colleagues aimed to examine the impact of vitamin D supplementation on psoriasis severity throughout the winter.

The double-blind, placebo-controlled, randomized clinical trial was performed through two winter seasons with two parallel groups. Randomization was computer generated. All participants, outcome assessors, and health care clinicians were masked to group allocation. Participants were followed for four months. The trial was performed at the clinical research unit of a hospital in Norway. It included adults from the general population with active psoriasis and 25[OH]D (25-hydroxyvitamin D) levels of less than 24 ng/mL.

Participants were randomized for four months to receive either Vitamin D (cholecalciferol, 100 000 IU, loading dose, followed by 20 000 IU/week) or placebo. The study's primary outcome was PASI (Psoriasis Area Severity Index). Secondary outcomes were self-administered PASI, Physician Global Assessment, and Dermatology Life Quality Index scores.

The study led to the following findings:

• A total of 122 participants (37.7% were women; mean age, 53.6 years; mean PASI score, 3.1; mean serum 25(OH)D, 14.9 ng/mL) were included. Of these, 60 were randomized to the vitamin D group and 62 to the placebo group.
• One hundred twenty participants (59 in vitamin D and 61 in placebo) completed the study. By completion, mean 25(OH)D levels were 29.7 ng/mL (vitamin D) and 12.0 ng/mL (placebo).
• There was no significant change in the PASI score between the groups (adjusted difference, 0.11).
• The authors observed no remarkable difference in change in self-administered PASI (adjusted difference, −0.60), Physician Global Assessment score (adjusted odds ratio, 0.66), or Dermatology Life Quality Index (adjusted difference, −0.86) between the groups.
• No adverse effects of the intervention were registered.

"Our findings indicate that vitamin D supplementation did not affect psoriasis severity," the investigators wrote. "Low baseline severity scores may describe the lack of measurable effect."

"The results may be affected by a less-than-expected degree increase in vitamin D levels in the intervention group based on previous experimental data from the same source population," they concluded.

Reference:

Jenssen M, Furberg A, Jorde R, Wilsgaard T, Danielsen K. Effect of Vitamin D Supplementation on Psoriasis Severity in Patients With Lower-Range Serum 25-Hydroxyvitamin D Levels: A Randomized Clinical Trial. JAMA Dermatol. Published online March 29, 2023. doi:10.1001/jamadermatol.2023.0357