If you or someone you love lives with rheumatoid arthritis (RA), you’ve likely done some research to understand what it is, why it happens, and the challenges it poses in everyday life. RA is one of many autoimmune diseases, and the exact reason why the immune system sometimes attacks healthy cells is largely unknown. There is still a lot to learn about the disease — and even with the most dedicated home-based research, a lot can be missed.

With ongoing rheumatology research, knowledge about RA is moving ever forward. Here are five RA facts that are lesser known and may not show up in your average search. Consider these facts as data points to help you or someone you love improve knowledge about RA and perhaps feel just a bit more informed while living with RA.

Fact 1: Smoking Increases Risk of RA — As Does Early Exposure to Smoke

When you think of smoking, you are more likely to think of lung damage than of joint damage. However, smoking and RA are related. Rheumatologist researchers have shown that smoking increases the risk of developing RA due to smoking-related biologic effects such as oxidative stress — low levels of antioxidants — and inflammation.

Moreover, there is evidence to suggest that passive exposure to tobacco increases one’s risk of developing RA. In other words, secondhand smoke exposure, such as from a smoking parent, is a risk factor. A 2019 cohort study (research that follows participants for a long time period) showed that nonsmokers who were exposed to smoke in childhood had a higher risk of developing RA, similar to that of active smokers. Perhaps not surprisingly, but still importantly, the same study found that people who have smoked and who were exposed to smoke in childhood faced increased risk of developing RA.

Fact 2: Giving Birth and Breastfeeding Impact Risk

Although the reproductive activities such as giving birth and breastfeeding may seem totally unrelated to joint health, they are associated with RA risk. They may also account for some of the sex-related differences in RA. New cases of RA are two to three times higher in women than in men, according to the Centers for Disease Control and Prevention (CDC).

According to the CDC, women who haven’t given birth may be at increased risk. Likewise, parity, or the number of children one has birthed, is shown to have a protective effect against RA.

Similarly, a history of breastfeeding decreases one’s risk of developing RA, according to the CDC. Evidence that giving birth and breastfeeding can reduce the risk of developing RA may be of interest and importance to women who have a family history of RA and are pregnant or are planning to become pregnant.

Why is the risk reduced? Rheumatologists have noted that intense hormonal changes — for example, high estrogen and progesterone levels — may be responsible for these protective effects. However, more research is needed on how pregnancy, giving birth, and breastfeeding affect the risk of RA, as there have been some inconsistencies in their protective and negative effects on RA development.

Fact 3: Vitamin D May Reduce RA Severity

Many rheumatology studies have investigated the association between vitamin D and RA, with evidence suggesting that deficiency in vitamin D may be linked to RA disease severity. As such, vitamin D supplementation — along with other medicines like disease-modifying antirheumatic drugs (DMARDs) — may be recommended for people living with RA.

However, researchers also have found that vitamin D levels may still be low in people with RA who regularly take vitamin D supplements. Disease severity and limited exposure to sunlight may explain why some people with RA have a lower therapeutic response to vitamin D supplements. For some people with RA, pain may be so severe that going outside is harder or less enticing. This, in turn, may contribute to why vitamin D supplementation does not always work.

Exercise is a lifestyle factor that could help people manage their RA symptoms and flare-ups, and exercising outdoors has the double effect of keeping joints flexible and reducing inflammation while increasing sunlight exposure.

Fact 4: Genetic Risk of RA Doesn’t Differ by Sex

Research has shown that RA is genetic, with an estimated inheritability rate of about 40 percent. Therefore, family history of RA has one of the strongest associations with your risk of developing the condition. Females also have a higher risk of developing RA, compared to males. That said, one might think these two risk factors might be somehow related. For instance, are women with a family history of RA more at risk of developing RA? In short, no.

Research shows that family history of RA doesn’t significantly differ by sex. In other words, the genetic component of RA appears to be equal for both males and females and thus doesn’t help explain why RA is more common in females.

More research is needed on what drives familial risk, such as genetic and environmental factors.

Fact 5: Cognitive Behavioral Therapy Is Effective for Pain Management

Painful, swollen, and tender joints are common symptoms of RA, so pain management is critical to better quality of life. When you think of pain management, you may envision physical interventions like drugs and physical therapy. But mental health interventions can also be effective.

Cognitive behavioral therapy (CBT) is a type of psychotherapy in which people learn to challenge destructive thought patterns that negatively affect behavior and mood. It is most often used to treat anxiety and depression, but can also be recommended for chronic pain. Research has proved CBT to be effective in pain management of RA, especially when it is done early on in the course of RA.

It is crucial to address both the mental health side of RA and the physical, since living with RA involves more than just living with joint pain. CBT can help fill that gap. The mind is powerful, and though a “mind over matter” approach isn’t always appropriate for people living with RA, mental exercises such as CBT can be just as important than physical ones — if not more so.

Talk With Others Who Understand

On myRAteam, the social network for people with rheumatoid arthritis and their loved ones, more than 191,000 members come together to ask questions, give advice, and share their stories with others who understand life with rheumatoid arthritis.

Which rheumatoid arthritis facts do you find the most compelling? Share your experience in the comments below, or start a conversation by posting on your Activities page.