Psoriasis Symptoms Are More Severe in People With Low Vitamin D

Supplements or foods that boost vitamin D levels might ease psoriasis symptoms for some people, a new study found.

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foods rich in vitamin D and supplements
Vitamin D levels can be increased through diet or supplements — but it’s a good idea to speak with your doctor first.Helen Rushbroo/ Stocksy; J. Anthony/Stocksy

Foods rich in vitamin D or supplements of the vitamin may reduce symptoms in some people with psoriasis, new research suggests.

For the study, which has not yet been published, scientists examined data on 491 people with psoriasis who had blood tests to check their vitamin D levels and reported how much of their body was covered with itchy, scaly patches (called plaques) that are a hallmark of this inflammatory skin disease.

People with the lowest vitamin D levels had the largest proportion of their bodies impacted by psoriasis, according to preliminary study results presented at the annual meeting of the American Society for Nutrition.

“Our results suggest that a vitamin D–rich diet or oral vitamin D supplementation may also provide some benefit to psoriasis patients,” said Rachel K. Lim, an MD candidate at the Warren Alpert Medical School of Brown University in Providence, Rhode Island, who presented the findings at the meeting, in a statement.

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Topical Vitamin D Has Long Been a Treatment Option for Psoriasis

Psoriasis is a relatively common skin condition, affecting about 2 percent of people in the United States, according to the American Academy of Dermatology (AAD). Topical vitamin D has long been among the treatments for psoriasis, often in combination with topical corticosteroids, according to AAD.

“Topical treatments for psoriasis often contain synthetic forms of vitamin D,” says Danilo Del Campo, MD, a dermatologist at Chicago Skin Clinic in Illinois who wasn’t involved in the new study. “These compounds are adept at regulating the skin cell growth cycle, slowing the overproduction of skin cells and reducing the inflammation and scaling characteristic of psoriasis.”

That’s because vitamin D helps regulate the immune system, and when levels are low, an overactive immune response may lead to rapid skin cell turnover, a defining feature of psoriasis, Dr. Del Campo says. Reduced sun exposure because of physical discomfort or concerns about how psoriasis looks can also contribute to lower vitamin D levels, Del Campo adds.

People naturally get vitamin D from sun exposure, but the AAD doesn’t recommend more time outside to boost vitamin D levels because of the skin cancer risk. Instead, people should consume lots of foods rich in vitamin D like milk and fatty fish, and take supplements if diet alone isn’t enough, the AAD advises.

What Is a Healthy Vitamin D Level?

Most adults should have a blood vitamin D level of at least 50 nanomoles per liter (nmol/L), according to the National Institutes of Health (NIH). Levels below 30 nmol/L can have negative health effects, including weakened bones, and levels above 125 nmol/L can also cause health problems, according to the NIH.

In the study, people with the fewest signs of psoriasis on their skin had average vitamin D levels of 67 nmol/L, compared with 56 nmol/L for participants with the most evidence of psoriasis on their skin. In addition, only 25 percent of people with the lowest amount of plaques were vitamin D deficient, versus 39 percent of the people with the highest number of plaques

“Maintaining vitamin D levels at a slightly higher threshold than typically recommended for the general population might be beneficial for individuals with psoriasis,” Del Campo says. “However, the evidence to confirm this is not yet robust, and more studies are needed.”

Should Everyone With Psoriasis Take a Vitamin D Supplement?

Deirdre Hooper, MD, a cofounder of Audubon Dermatology in New Orleans, says that she recommends every psoriasis patient take a daily 600 mg vitamin D supplement. The study results suggest that anyone with psoriasis should get their vitamin D levels checked and take higher supplement doses if needed to get their vitamin D levels up to a healthy level, adds Dr. Hooper, who wasn’t involved in the study.

“It definitely makes sense for psoriasis patients to check their vitamin D levels, and if low, definitely supplement,” says Faranak Kamangar, MD, the chair of dermatology at the Palo Alto Medical Foundation in California.

But if lab levels are normal, it’s unclear how much vitamin D supplements will help, says Dr. Kamangar, who wasn’t involved in the new study.

Still, it makes sense for psoriasis patients — even those with normal vitamin D levels — to use topical vitamin D treatments to help clear up symptoms, Kamangar says. “The topical use of vitamin D decreases the risk of high levels of calcium that can be caused by high doses of vitamin D taken orally. Topical vitamin D analogues are very safe,” Kamangar adds.