Vitamin D supplementation does not affect the severity of psoriasis during the winter time according to recent findings, although lower baseline severity scores might be the reason for the study’s lack of measurable effects.

While topical vitamin D analogues are often used in psoriasis treatment, oral supplement effects were not yet established.

The study’s investigators conducted their research to evaluate psoriasis severity throughout the winter with vitamin D supplementation.

This research was authored by Marita Jenssen, MD, from the Department of Dermatology at University Hospital of North Norway. Jenssen and her team hypothesized that psoriasis during winter could be reduced by elevating 25-hydroxyvitamin D (25[OH]D).

“We examined the effect of vitD supplementation on psoriasis severity as measured by Psoriasis Area Severity Index (PASI), Physician Global Assessment (PGA), self-administered PASI (SAPASI), and Dermatology Life Quality Index (DLQI) scores,” Jenssen and colleagues wrote.

Background and Findings

The investigators performed a clinical trial over the course of 2 winter seasons from 2017-2018 and 2018-2019, both at the clinical research unit of the University Hospital of North Norway in Tromsø.

The team’s research involved adults recruited from the general population in Tromsø who reported active plaque psoriasis and 25-hydroxyvitamin D (25[OH]D) levels that were found to be below 24 ng/mL.

The team’s study involved 2 parallel groups, and randomization was computer-generated. The trial was double-blind, placebo-controlled, and the team followed each study participant for 4 months as part of their work. Each and every participant, clinician, and outcome assessor was kept unaware of the groups’ assignments.

The investigators performed their analyses in May of 2022, deciding on the primary outcome being PASI scores, and secondary outcomes being PGA, self-administered PASI, and DLQI scores.

The interventions used in their study were cholecalciferol (100,000 IU loading dose, and then 20,000 IU/week) or the placebo for a total of 4 months.

In the end, the investigators had recruited a total of 122 study participants, with 46 being women and the mean age being 53.6 years. Additionally, they noted that the mean PASI score was 3.1, the mean serum 25(OH)D level was 14.9 ng/mL.
They randomized 49.2% of the participants to the vitamin D arm of the study and 50.8% to the placebo arm.

It ended up that 120 total participants—49.2% in the vitamin D group and 51.8% in the placebo group—completed their study. The team reported that by the end of the study, mean 25(OH)D levels were reported to be 29.7 ng/mL in the vitamin D arm and 12.0 ng/mL in the placebo arm.

Overall, the researchers noted that there was no major difference in PASI score changes between both of the groups.

Additionally, they found no substantial difference in change in self-administered PASI score, PGA score, or DLQI between the 2 arms. They added that there were no registered adverse effects from the intervention.

Notably, they did point out low baseline scores in severity for the participants may be the explanation for the reported lack of measurable effects observed.

They added that the increases in levels of 25(OH)D for the intervention arm were to a lesser degree than expected, based on prior data from the same source population. This too may have influenced the team’s results.

“Future trials should include cases with more extensive psoriasis and/or use severity measurements, which are more sensitive in the lower spectrum,” they wrote. “Also, future trials should ensure the achievement of the targeted 25(OH)D level, possibly aiming at the 25(OH)D level that is achieved through UV-B treatment (>40 ng/mL).”

References

1. ^{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.}