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The Facts About Vitamin D and Rheumatoid Arthritis

There’s a connection between the sunshine vitamin and this chronic condition. Find out what the research says, and what it means for you.

News flash: Vitamin D is the latest wonder supplement. We already know that it may improve mood, ease chronic pain, and heart health (studies have linked low levels of D with heart disease and heart attacks). It may even reduce fracture risk in the elderly. But—wait for it—it could also help treat and improve the symptoms of your rheumatoid arthritis. “The influence of vitamin D on the immune system is just being understood,” says Robert Hylland, M.D., a rheumatologist in Muskegon, MI. Here's what the experts know now.


Arthritic Seniors hands holding a vase
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What’s the Link Between Rheumatoid Arthritis and Vitamin D?

While studies show an association between RA and D deficits, researchers don't yet have solid evidence of causality. That means we don’t know if low D contributes directly to the autoimmune disease, or if it’s just the consequence of a dysfunctional immune system. But ultimately, it may not matter so much which is correct. By getting enough D, “You’re feeding the immune system what it needs to limit attacks,” says Dr. Hylland.


Hand xrays showing advanced rheumatoid arthritis
Hand x-rays showing advanced rheumatoid arthritis iStock

Can Getting More Vitamin D Improve RA Symptoms?

It might. “Rheumatoid arthritis patients tend to have lower vitamin D levels,” says Dr. Hylland. “So we recognize it probably plays an important role.” Dr. Hylland estimates over half of his own RA patients are D deficient. Vitamin D levels may impact the severity of RA, too. In a study from India, RA patients with the most severe symptoms had D levels far lower than the average level among patients in remission or those with mild symptoms. Other studies have found similar results, prompting medical researchers to speculate whether vitamin D supplementation should be considered in RA treatment.


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How to Check Your Vitamin D Levels

If you're worried that low levels of vitamin D might be playing a role in your RA symptoms, ask your doctor for a simple blood test called a total serum 25-hydroxy vitamin D test, which is generally covered by insurance, says Weijia Yuan, M.D., a rheumatologist at the Hospital for Special Surgery in New York City. While experts are not all in agreement on what constitutes a healthy level, the National Institutes of Health recommends between 20 and 50 ng/mL. (Anything below 20 is considered inadequate, and below 12 is deficient.) “Ideally, you should be around 50,” says Dr. Yuan.


Several vitamin D pills next to bottle
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How Much Vitamin D Should I Take as a Supplement?

If your vitamin D levels turn out to be low, you'll want to bone up. The NIH recommends 600 IU of vitamin D a day for those age 70 and under, and 800 IU if you are over that age. But deficient adults may benefit from adding up to 2,000 IU a day (or up to 4,000 IU if you’re over 75) in some cases. Dr. Yuan recommends her rheumatoid arthritis patients take a daily supplement of 2,000 IU of vitamin D3, the most easily absorbed kind. Pro tip: If you’re on a calcium supplement, try taking both together—they work synergistically for better bone health.


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Can I Get Vitamin D Directly Through Food?

Vitamin D can be found in several foods, but not in large quantities, so it can be tough to get enough through your diet alone. Egg yolks, mushrooms, and fortified foods have some vitamin D. But the best sources are fatty fish like salmon, trout, swordfish, mackerel, and tuna. Bonus: The omega-3s found in fish also have anti-inflammatory properties that may help control the inflammation of rheumatoid arthritis. Eating fish at least twice a week is associated with lower disease activity in RA patients, a study in Arthritis Care & Research found.


Friends sunbathing on a boat.
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Can I Get Vitamin D From the Sun?

This one’s tricky. Yes, spending time in direct sun exposure can boost your D levels—just 15 minutes can give you the equivalent of 2,000 to 4,000 IU. However, doctors may discourage this because of the risk of skin cancer, which occurs more frequently in rheumatoid arthritis patients on some biologic drugs. “It’s safer and more effective to use an oral supplement,” says Dr. Hylland. That said, no need to fear the outdoors. Just wear sunscreen!


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Once I Start Taking Vitamin D, When Will I See Improvement?

Don’t expect miracles. Vitamin D can play a role is easing some of the symptoms related to rheumatoid arthritis, but it is by no means a panacea. You still need your medication and other forms of therapy to keep the disease under control. “You’re not going to take 2,000 IUs of vitamin D and suddenly feel like your [insert achy body part] is better,” notes Dr. Hylland. Dr. Yuan also encourages patience: “When you have a severe (active) disease, it can be very hard to raise the level of vitamin D. But when the disease quiets down, it’s much easier.”


Ultrasonography of kidney, showing left kidney stone
Ultrasound of kidney, showing left kidney stone iStock

Yes, It's Possible to Have Too Much Vitamin D

Supplementing with vitamin D is a balancing act. Excessive vitamin D supplementation over time can be toxic, leading to abnormal heart rhythms, kidney stones, muscle weakness, and confusion. Still, this is rare and happens only with extremely high-dose supplementation—60,000 IU a day for several months, according to the Mayo Clinic. Your doctor can help you find the right dose for you. (Probably a lot lower than that!)


Person taking vitamin D supplement
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What to Know About RA Medication and Vitamin D

This part's important: Some medications for rheumatoid arthritis can affect how your body absorbs D, in particular hydroxychloroquine (Plaquenil) and corticosteroids. If you’re on one of these medications, talk to your doctor before taking a vitamin D supplement. It doesn't mean you can't still take vitamin D, but your rheumatologist may want to change up the treatment plan you're on, or at the very least, review it to ensure there will be no negative interactions between your meds and the vitamin supplement.


This article was originally published August 15, 2013 and most recently updated April 28, 2022.