According to a study published in November 2018 in the Journal of Natural Science, Biology and Medicine, vitamin D deficiency is more common in people with RA — and may be one of the causes that leads the condition to develop or worsen. “Vitamin D is a hormone that plays a critical role in regulating the immune system,” says Sonya Angelone, MS, RDN, a registered dietitian based in San Francisco and a spokesperson for the Academy of Nutrition and Dietetics. “And RA is a condition that results from problems with the immune system.” According to the Office of Dietary Supplements, adults should aim to get 600 IU of vitamin D daily — though your doctor may adjust your recommended daily intake based on your specific needs. Most people with RA aren’t getting enough of this essential nutrient. Vitamin D deficiency is common among people with RA, and low levels of vitamin D can exacerbate RA symptoms and even cause bones to become brittle. What’s more, certain RA medications, like oral steroids, can further contribute to vitamin D deficiency. The good news is that getting the vitamin D you need may help lessen the severity of your RA and prevent bone loss.

1. Spend more time outside

The Arthritis Foundation recommends spending 10 to 15 minutes in the sun every other day, and possibly longer for those with darker skin. Be careful, however, because time spent in the sun can increase your risk of skin cancer. According to the Skin Cancer Foundation, people who apply sunscreen daily can maintain healthy vitamin D levels — so sunscreen can help you safely get the sun exposure you need. If you live in a climate where you’re unable to get much sun, talk to your doctor about using an ultraviolet (UV) lamp, though the health risks of UV exposure still apply.

2. Sit by a window 

Just make sure it’s open, as most windowpanes block the kind of sunlight that promotes the production of vitamin D.

3. Eat more fish

Focus on fish that’s high in vitamin D. Angelone suggests:

Cod liver oil — 1 teaspoon has 453 IU of vitamin DSalmon — 3 ounces has 447 IUTuna — 3 ounces has 154 IUSardines — 2 fillets have 46 IU

And raw fish has more vitamin D than cooked, so don’t be shy about eating sushi or sashimi.

4. Incorporate more vitamin D-fortified foods in your diet

Angelone suggests eating more of these vitamin D-fortified foods:

Fortified orange juice — 1 cup has 137 IUEggs — 1 large egg has 41 IUFortified cereals — 1 cup has 40 IUMushrooms — 1 cup has 2 IU

5. Take a vitamin D supplement

If you’re vitamin D deficient, it’s likely that your doctor will recommend a vitamin D supplement. Angelone says vitamin D supplementation can help improve disease activity for people with RA.