Vitamin D got its nickname, "the sunshine vitamin," because sun exposure helps promote vitamin D production in the body. This essential nutrient is also found naturally in a few foods such as oily fish (mackerel, salmon) and is used to fortify milk, baby formula, cereal, and juice. But changing lifestyles and diets mean that many of us are lacking in vitamin D. In fact, it's estimated that about 75 percent of American teens and adults don't get enough vitamin D, and studies suggest that this may play a role in several chronic diseases, including arthritis.
Just what role does vitamin D play in arthritis and arthritis symptoms? "It's hard to know at what level it's working," says Carolyn Dean, MD, ND, the Maui, Hawaii-based medical director for the Nutritional Magnesium Association and author of Future Health Now Encyclopedia. Vitamin D may affect arthritis pain by affecting the joints directly or by interacting with the immune system, she adds.
Arthritis and Vitamin D: What the Research Says
Research has found that vitamin D may play a significant role in joint health, and that low levels may increase the risk of rheumatologic conditions such as arthritis. Several studies have found low blood levels of vitamin D in patients with osteoarthritis of the hip and knee. In another study of more than 2,000 people, researchers found that vitamin D deficiency was strongly associated with disabling symptoms among those with rheumatoid arthritis. While it may be true that people with arthritis don't get as much sun exposure — exposure to the sun helps promote vitamin D production in the body — the study authors adjusted for that and still found that being vitamin D deficient was linked to arthritis pain.
In the United States, studies have also suggested that women who live in northern states, and hence tend to get less daily sun exposure, may be at higher risk of developing rheumatoid arthritis compared with women living at more southern latitudes. In a recent study of data from the Nurses' Health Study, researchers found women who lived in the northeastern United States had a significantly higher risk of rheumatoid arthritis.
Getting Enough Vitamin D
In addition to helping prevent arthritis, getting enough vitamin D may also lower the risk for other autoimmune diseases, cancer, heart disease, type 2 diabetes, bone fractures, depression, and even the flu.
If vitamin D has the potential to improve your arthritis symptoms and your overall health, you want to know that you're getting enough.
Consider these strategies to keep your vitamin D levels optimal:
- Spend some time in the sun. Dermatologists will tell you to slather on sunscreen any time you're outside to avoid skin cancer — and rightfully so since skin cancer can be deadly. Nevertheless, sun exposure is a good way to build up your levels of vitamin D. Luckily, it takes just a few minutes of sun exposure for your body to use the sun's rays to make vitamin D. Be sure to apply or reapply sunscreen after getting some brief exposure to sunshine each day.
- Consider a daily supplement. In addition to soaking up some sun, it's probably a good idea to take a vitamin D supplement to be sure you're getting enough, especially if you live in northern states where the sun's rays may not be strong enough for your body to make enough vitamin D in the winter. Doctors recommend taking 800 to 1,000 international units, or IU, of vitamin D a day. (Some multivitamins include 1,000 IU of vitamin D, so check the label.) If you buy the supplement separately from your multivitamin, be sure to choose vitamin D3, a natural form of vitamin D that lasts longer in your body, advises Dr. Dean.
- Get tested. Symptoms of vitamin D deficiency include chronic pain, frequent infections, gastrointestinal problems, depression, and weak bones. If you think you may be deficient, or if you're thinking about taking more than 1,000 IU of vitamin D a day, have your doctor test your blood levels, Dean suggests. Then you'll be able to take a safe and effective dose.
Although vitamin D is found in some foods, it can be hard to get it from your diet, Dean says. Fatty fish such as salmon, tuna, and mackerel contain vitamin D, but they may also contain mercury and shouldn't be eaten in large quantities. Foods that are fortified, such as milk, have the synthetic form of vitamin D and don't offer as many long-term benefits, Dean adds.
Focus on getting a healthy amount of sun exposure and consider taking a supplement that contains vitamin D3 to help with arthritis symptoms.