New Research Suggests a Link Between Vitamin D Levels and Severity of Psoriasis

Getting enough vitamin D through diet or supplements might be helpful in managing psoriasis, an autoimmune disease that causes itchy, scaly patches on the skin, researchers say.

The claim comes from a new study presented Tuesday at NUTRITION 2023, the annual meeting of the American Society for Nutrition. Though the findings are preliminary and haven’t yet been published in a peer-reviewed journal, experts say that upping your intake of vitamin D could be a relatively low-risk way of reducing psoriasis severity.

“The role of oral vitamin D supplementation as a treatment option remains controversial,” Rachel Lim, presenting study author and MD candidate at the Warren Alpert Medical School at Brown University, told Health. “Our study suggests that following a vitamin D-rich diet or starting oral vitamin D supplementation may provide some benefit to psoriasis patients, but further research is certainly warranted.”

Psoriasis is a chronic disease that affects approximately 8 million people in the U.S. With the condition, a person's immune system becomes overactive, causing skin cells to multiply quicker than normal. This results in patches of skin that are thick, scaly, and inflamed—commonly on the scalp, elbows, or knees due to increased friction in those areas.

It's not yet clear what causes psoriasis—the new research is important since experts haven't yet identified many modifiable risk factors for severe psoriasis, Saakshi Khattri, MD, an associate professor of dermatology at the Icahn School of Medicine at Mount Sinai, told Health.

“If low vitamin D, once modified, improves [psoriasis], that would be helpful because we could use a modifiable approach,” she said. “I’m excited for the next step [in this research.]'

Below, experts explain what the new study could mean for future psoriasis treatments, why it’s essential to get enough vitamin D, and how to work more into your diet.

Previously, research on the connection between vitamin D levels and psoriasis severity was limited.

“There is existing evidence for an association. However, most previous studies have been conducted outside of the U.S. and in small study populations,” Lim said. “We sought to investigate whether this relationship would be replicated in a large, nationally representative U.S. population.”

Lim’s team relied on data from the National Health and Nutrition Examination Study (NHANES), a program run by the Centers for Disease Control and Prevention (CDC) that’s been collecting information since the 1960s.

They identified 491 NHANES participants who had psoriasis from 2003–2006 or from 2011–2014. They analyzed their vitamin D levels as well as how much of their body surface area was affected by psoriasis.

Taking factors like age, body mass index, race, gender, and smoking status into account, Lim’s team determined that lower vitamin D levels and vitamin D deficiencies were significantly associated with greater psoriasis severity. They also found that patients with the highest amount of vitamin D had the lowest amounts of body surface area affected by psoriasis.

“We found that lower serum vitamin D levels were associated with more severe psoriasis, in a dose-dependent fashion,” Lim explained.

Though research on the connection between vitamin D and psoriasis is still in its infancy, Lim said experts do have a theory as to why the two might be related: It's already used as a treatment, in a way.

Vitamin D analogs—also known as synthetic vitamin D—are currently used to treat psoriasis in some cases. This synthetic vitamin D is not the same as the kind you can buy in the supplements aisle; vitamin D analogs for psoriasis come in topical form.

These vitamin D analogs bind to vitamin D receptors on keratinocytes, which are cells in the skin, to prevent or slow their growth, Lim said. Because this synthetic form of vitamin D is used as a treatment for psoriasis, scientists speculated that dietary vitamin D may also have an effect.

'Topical synthetic vitamin D creams are emerging as new therapies for psoriasis, but these usually require a doctor's prescription,' Lim said in a news release. 'Our results suggest that a vitamin D-rich diet or oral vitamin D supplementation may also provide some benefit to psoriasis patients.'

Because there are few modifiable risk factors for psoriasis—including smoking and alcohol, stress, and sun exposure—a low-risk lifestyle adjustment like introducing more vitamin D into your diet may sound promising for people with the disease.

However, experts caution that this research is still too new to go out and begin supplementing with vitamin D on your own. 'This is speculative at this moment,' Khattri said, 'but I think it's worthwhile bringing it up to your dermatologist or primary care doctor.'

Working closely with a healthcare provider is typically a good idea when it comes to vitamin D supplementation in general—though vitamin D toxicity is rare, it is possible. Too much vitamin D in your body can lead to hypercalcemia, or a buildup of calcium in the blood, and can cause nausea and vomiting, weakness, and frequent urination.

If a doctor thinks it’s necessary, they may decide to take a blood test to know if you have low vitamin D. (Without this test, there’s no way of knowing for sure, Khattri said.) If so, they can help you make a plan to incorporate more vitamin D into your diet.

Future studies are also expected to better examine the role of vitamin D supplementation in psoriasis treatment. “Further research, such as randomized trials, is warranted before any firm medical recommendations may be made,” Lim said.

Though the new research focuses on people with psoriasis, it's worth noting that many people don't get enough vitamin D.

'Low vitamin D is a pretty ubiquitous problem in the population in general,' Khattri said. About 1 in 4 people in the U.S. have vitamin D levels that are either too low or inadequate for bone and overall health.

Though vitamin D supplements do exist, most of your nutrients should come from your diet. Food that are naturally rich in vitamin D include:

In the U.S., fortified foods also provide ample amounts of vitamin D. The American milk supply, for example, is voluntarily fortified with about 3 micrograms per cup of vitamin D. Other fortified foods include:

While more research is needed before doctors can make any sweeping statements about the role of vitamin D in psoriasis treatment, it’s worth exploring if you’re having trouble managing your symptoms.

“If this truly pans out, this could be helpful in lessening the severity of psoriasis,” Khattri said, “but we need further studies.”