Can Vitamin D Supplements Help Your Psoriatic Arthritis?

Note: The U.S. Food and Drug Administration (FDA) does not approve supplements for safety or effectiveness. Talk to a healthcare professional about whether a supplement is the right fit for your individual health, and about any potential drug interactions or safety concerns.

If you’re living with psoriatic arthritis (PsA), you know it’s more than just joint pain. This chronic disorder causes the immune system to attack healthy cells, triggering joint inflammation, swollen fingers and toes, and itchy, scaly psoriasis skin patches.

While medications and steroid injections are common treatments, you may be curious to explore additional ways to manage symptoms, such as supplements. One popular option: vitamin D capsules and tablets.

Vitamin D plays a well-established role in bone and immune health, but can it really help with psoriatic arthritis symptoms?

The short answer: probably.

Vitamin D is a fat-soluble vitamin that helps your body fight off infections and regulate inflammation. Both are relevant to autoimmune conditions like psoriatic arthritis and psoriasis, a related autoimmune condition that often coexists with psoriatic arthritis.

“Vitamin D is strongly linked with skin immunity because of its ability to suppress the immune response in skin inflammation, making it a viable treatment for psoriasis,” says Erin Hammett, DO, a rheumatologist at Sansum Clinic in Santa Barbara, California. Simply put, vitamin D may help calm immune system overactivity.

The three main vitamin D sources include sunlight, food, and supplements. Your body naturally produces vitamin D when your skin is exposed to sunlight, particularly ultraviolet B (UVB) rays.

But “modern humans are usually indoors and don’t live with adequate exposure to sunlight,” says Aly Cohen, MD, a Princeton, New Jersey–based rheumatologist and author of the book Detoxify.

That’s where supplements and vitamin D-rich foods such as the following come in:

Fatty fish like salmon and mackerel
Beef liver
Fortified dairy products
Egg yolks
Fish liver oil

Research shows that 82 percent of people with psoriasis and almost 75 percent of those with psoriatic arthritis have a vitamin D deficiency. Studies also suggest a link between lower vitamin D levels and an increase in the severity of psoriasis with and without psoriatic arthritis.

While research specific to the benefits of taking vitamin D for psoriatic arthritis is still emerging, findings about the positive effect of vitamin D on psoriasis are encouraging. One study showed that vitamin D–boosting UVB light exposure, called phototherapy, can effectively treat psoriasis.

Other research suggests vitamin D pills could improve psoriasis and its related conditions for those who are deficient in this nutrient. Not all studies have shown an effect, however, and more research is needed.

“These are good studies that both support the large body of evidence that patients with psoriasis and psoriatic arthritis have lower levels of vitamin D, and that disease activity is higher in patients with low serum levels of vitamin D,” says Dr. Hammett, adding that she sees similar results in her clinical practice.

“Individuals with psoriasis and psoriatic arthritis must have vitamin D levels checked,” Hammett says. “If deficient, they should start supplementation, as it could improve their disease.”

Still, not all findings are glowing. One clinical trial found that vitamin D supplements had minimal effect on the severity of psoriasis during the winter, though researchers noted that the initial mildness of the participants’ symptoms may have influenced the results.

The takeaway? There’s enough evidence to support using vitamin D as a supportive therapy, but not as a standalone treatment for psoriatic arthritis.

“Vitamin D supplements won’t make everything better,” says Dr. Cohen. “But generally, it’s far more appropriate to give patients vitamin D in reasonable amounts than it is not to.”

So, should you consider adding a vitamin D supplement to your psoriatic arthritis treatment regimen?

“Typically, yes,” says Hammett. “Individuals with skin psoriasis tend to have lower vitamin D levels, which can make psoriasis harder to control and flare psoriatic arthritis as well.”

Cohen agrees: “As an immune disease specialist, I tell patients they need to get their vitamin D levels into the high-normal range — that’s when the immune system uses it most effectively and where we see the strongest health outcomes.”

It’s also important to remember that vitamin D supplements are most helpful when used alongside standard medical treatments, not in place of them, she adds.

The typical recommended daily value of vitamin D from all sources, including food and sunlight, is 15 micrograms (mcg), or 600 international units (IU), for most adults. Sunlight can help you meet your daily needs, but the recommended daily value assumes you get little to no sun exposure.

For people with psoriatic arthritis and healthy individuals alike,15 mcg is often insufficient, says Cohen. There’s no one-size-fits-all vitamin D daily dosage when you have psoriatic arthritis, explains Cohen — it ultimately depends on your baseline vitamin D status and overall health.

Hammett generally recommends daily doses of 2,000 IUs for those with adequate vitamin D levels. Ultimately, though, she says it’s best to start with a simple blood test to check your current vitamin D levels. If your results come back low, your doctor may suggest a different supplement dose to help bring levels up and possibly reduce disease activity.

Here’s Hammett’s general dosing guide for vitamin D3 (the type of vitamin D most often used in supplements) based on blood test results:

Vitamin D levels of less than 15 nanograms per milliliter (ng/mL): 50,000 IUs per week for six to eight weeks, then 5,000 IUs per day
Vitamin D levels of 15 to 20 ng/mL: 5,000 IUs per day
Vitamin D levels of 20 to 25 ng/mL: 4,000 IUs per day
Vitamin D levels of 25 to 30 ng/mL: 2,000 IUs per day

It’s important to talk to your healthcare provider before starting a supplement to ensure you’re taking the right dose. Because vitamin D is fat-soluble, it can build up in your body and become toxic at high levels, says Cohen. Multivitamins and other supplements often contain vitamin D, so be sure to review all your over-the-counter products and share them with your healthcare team so you know the right amount of vitamin D to take each day. Symptoms of too much vitamin D include nausea, vomiting, muscle weakness, and kidney issues.

Because an excess of vitamin D is risky, regular monitoring is also vital. Cohen recommends getting a follow-up blood test three to four months after starting supplementation to check your vitamin D levels and adjusting your supplement dose if necessary.

Vitamin D plays a meaningful role in immune regulation and inflammation, making it a promising supportive therapy for people with psoriatic arthritis (especially those who are deficient).
Research shows a strong link between low vitamin D levels and more severe psoriasis and psoriatic arthritis, though more high-quality studies are needed to confirm how much supplementation can reduce symptoms.
Before starting supplements, talk to your doctor about getting your vitamin D levels tested, since the right dose depends on your current levels. Supplementing without knowing your levels may lead to ineffective dosing or potential toxicity.
Vitamin D should be used as a complement to — not a replacement for — standard psoriatic arthritis treatments. If you’re deficient, correcting that can be a step toward more effective psoriatic arthritis management.

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