Some patients with psoriasis may see an improvement in their symptoms by taking oral vitamin D supplements, especially during the colder months, according to a study published online in the Journal of Dermatological Treatment (Feb. 26, 2018).
“This study was partly motivated by observations that some people with psoriasis report a reduction in symptoms during the summer months, when vitamin D production in the skin is usually at its highest,” said study author Michelle Ingram, PhD candidate in the Department of Human Nutrition at Massey University in Albany, New Zealand, in a press release. “Vitamin D incorporated into a cream or ointment is also a relatively effective treatment for psoriasis, yet no one had looked into whether vitamin D supplementation might be of similar benefit.”
The investigation focused on 101 patients, 18 years of age and older, with mild, moderate, or severe psoriasis. The trial was randomized, double-blinded, and placebo-controlled. Over the span of 12 months, 67 patients were prescribed 100,000 international units (IU) of vitamin D3 each month (200,000 IU at baseline). Thirty-four participants were given a placebo. Psoriasis Area and Severity Index (PASI) scores and serum 25-hydroxy vitamin D [25(OH)D] concentrations were assessed every three months. The difference in PASI scores between groups over time was the primary outcome.
The main findings of the study were inconclusive due to an unexpected increase in vitamin D levels in the placebo group, as 25(OH)D levels increased in both groups. The researchers attributed this spike to sunlight exposure.
In addition, PASI did not differ between the two experimental arms at any time. A substantial inverse relationship existed between PASI scores and 25(OH)D, with elevation of 25(OH)D by up to 125 nmol/L associated with mild decreases in PASI scores.
“While we could not confirm whether vitamin D supplementation is beneficial for psoriasis per se, we have shown that increased vitamin D levels, which can be achieved through supplementation or sun exposure, are related to less severe psoriasis,” said Dr. Pamela von Hurst, PhD, associate professor in the School of Sport, Exercise, and Nutrition and co-director of the Vitamin D Research Centre at Massey University in Albany, New Zealand.
Although the direct link between vitamin D supplements and improved psoriasis symptoms is still unclear, results of the trial provide evidence of a link between higher levels of vitamin D and less severe manifestations of psoriasis.
Study author Michelle Ingram.
Photo courtesy of Massey University.
“Interestingly, this relationship was only found in about two-thirds of our participants, suggesting that vitamin D may be beneficial for some people with psoriasis, yet make no difference for others,” said Ingram. “It was not clear from our data why there might have been a difference in response—understanding the variability of response to psoriasis treatments in general is a long-term challenge and one that future research will hopefully be able to address.”