Does taking vitamin D help with psoriasis?

Experts cannot say if oral vitamin D helps improve psoriasis symptoms, because overall, trial results have been mixed. While some open-label studies show a moderate to marked improvement (with some reports of remission), most double-blinded RCTs have shown only slight or no improvement.

There does seem to be a correlation between low vitamin D levels and psoriasis, so some experts recommend vitamin D levels should be measured in people with psoriasis and those shown to be deficient should be supplemented. In addition, most trials reported no side effects from vitamin D supplementation (one reported hypercalcemia) with dosages of 0.25 ug/day to 2 ug/day, so supplementation could also be considered on a case-by-case basis with monitoring.

The exact dosage for vitamin D supplementation in people with psoriasis is unknown. The recommended daily intake is 400–800 IU/day or 10–20 micrograms/day but some studies suggest higher dosages (1,000–4,000 IU [25–100 micrograms]) may be needed to maintain optimal blood levels.

Trial results for vitamin D in psoriasis

Several trials have concluded topical vitamin D (eg, calcipotriene topical) is an effective treatment for plaque-type psoriasis. But many experts have speculated about whether or not oral vitamin D would be just as useful.

Reports of the beneficial effects of oral vitamin D for psoriasis were first published around 1985 when a case study reported psoriasis remission following oral vitamin D treatment. But in general, trial results for oral vitamin D supplementation in psoriasis have been mixed. Those studies that have tended to show favorable results were mostly unblinded, small, case studies, and most reported moderate to marked improvement after administration of oral vitamin D (dosages ranged from 0.25 ug/day to 2 microgram/day), with some reporting complete remission. One trial reported worsening of psoriasis in 22% of people.

A large systematic review that identified 107 relevant articles regarding oral vitamin D supplementation in psoriasis, found only 10 that met their strict criteria for inclusion into the review. Most of these trials had small numbers of participants (n = 6 to 101), and only 4 were randomized, double-blinded, and controlled. The authors did not make a recommendation about oral vitamin D supplementation in psoriasis and concluded that more large-scale studies were needed.

In this review, the randomized placebo-controlled trial by Hata et al reported no change in PASI score with 4000 IU/day vitamin D3 over 6 months in people with mild psoriasis. In the 4 randomized, double-blind, placebo trials:

• Siddiqui et al (1990) reported only slight improvement with Vitamin D3 supplementation (1 ug/day) in 45% of people after 12 weeks
• Jarret et al (2018) found no benefit of monthly vitamin D3 supplementation (100,000 IU/month for 4 years) in patients with mild psoriasis over 50 years old
• Ingram et al (2018) found no benefit for monthly vitamin D3 supplementation (100,000 IU/month for 11 months after an initial loading dose of 200,000 IU) in patients with chronic psoriasis
• Disphanurat et al (2019) found moderate improvement (PASI score decreased at 3 and 6 months) with fortnightly vitamin D2 supplementation (20,000 IU every 2 weeks for 6 months) in patients with chronic plaque-type psoriasis and mild psoriasis

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Do people with psoriasis tend to have low vitamin D?

Numerous studies have reported low serum vitamin D levels in people with psoriasis although these do tend to show seasonal variations. People with severe psoriasis tended to have the lowest vitamin D levels.

What are the possible side effects of vitamin D supplementation in people with psoriasis?

Possible side effects of vitamin D include high blood calcium levels, high urinary calcium levels, and kidney stones. Long-term administration of greater than recommended dosages could result in bone demineralization. But most studies have reported no side effects with dosages within the recommended range.