Harvard Health Letter

Psoriasis and vitamin D deficiency

A topical supplement may help your treatment.

Fighting psoriasis, a condition characterized by patches of irritated, flaky skin that usually appear on the elbows and knees and across the trunk, is difficult throughout the year, especially in winter. New research may help explain why. Scientists in Italy found that people with psoriasis also suffer from vitamin D deficiency.

"We speculated that vitamin D might be low in psoriasis patients, but this is the first good study that substantiates it," says Dr. Suzanne Olbricht, an associate professor of dermatology at Harvard Medical School.

What is psoriasis?

What is Psoriasis?

Deficiency link

Most of the vitamin D in our bodies is made when sunlight strikes the skin. Dr. Olbricht says that vitamin D deficiency doesn't cause psoriasis, but it may impair the body's ability to keep skin healthy. In fact, researchers found that vitamin D deficiency was common in people with chronic plaque psoriasis. Deficiency was more marked in the winter, when psoriasis is often at its worst and less sunlight strikes the skin.

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