Genetics can play a role—but there are other risk factors to know, too.

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When you're diagnosed with a health condition, one of the first questions you're likely to ask is how or why this happened. Does the condition run in your family? Did you do something (or not do something) that increased your risk for developing it? Was there anything you could have done to prevent it, or was it just luck of the draw?

It's only natural to wonder and ask these questions, but sometimes there are answers and sometimes there aren't. And sometimes, like in the case of rheumatoid arthritis (RA), there might be a whole bunch of reasons.

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"Rheumatoid arthritis is multifactorial," Juan J. Maya, MD, a rheumatologist at the Rheumatology Center of Palm Beach and medical advisor to CreakyJoints, tells Health. "[That means] it's not just one single thing but a few things [put together] that have been shown to increase your chances."

What are the most common risk factors for RA, and do you have any of them? Here's what you need to know.

Genetics

There are a few known risk factors for RA that you can't do anything about—the biggest of which is your genetic profile. In other words, if other members of your family have or have had RA, you also have an increased risk of developing it yourself.

Exact numbers are lacking, but according to the National Rheumatoid Arthritis Society, first-degree relatives of people with RA have three times the risk of developing it themselves; other studies suggest that inheriting RA genes may cause more than half of all cases.

However, an increased risk doesn't mean a guarantee, Robert Koval, MD, rheumatologist at Texas Orthopedics in Austin, Texas, tells Health. "RA has a genetic component, and it does run in families, but while your genes set you up for disease it's not the be all, end all as to whether or not you'll get it," he says.

Many people carrying genes that can cause RA will never develop the condition, and not everyone who develops it was genetically predisposed, either. But genetics remains one of the largest risk factors at play.

Age

Technically anyone can be affected by RA, but according to the Centers for Disease Control and Prevention (CDC), your chances increase with age; the most common age for people to develop RA is during their sixties.

According to the Arthritis Foundation, RA usually begins between the ages of 30 and 60 for women; and men under the age of 45 are only rarely diagnosed with the condition.

Smoking

As if cancer wasn't a big enough reason to avoid smoking, you can add RA to the list, too. Plus, the fact that smoking is a preventable risk factor makes it even more noteworthy here—a 2014 review published in the International Journal of Molecular Sciences concluded that smoking not only increases your chances of developing RA, but it can also make your symptoms and disease progression worse.

"People that smoke develop RA about 10 years before they otherwise would have if they are already genetically predisposed," says Dr. Koval, adding that the chemicals in nicotine can trigger the heightened immune response that can lead to RA.

Poor dental hygiene

What does brushing your teeth have to do with RA? Quite a lot, as it turns out. Dr. Maya notes that people with poor dental hygiene or periodontal disease often have more severe RA symptoms (and vice versa).

The connection seems to be inflammation: RA doesn't just cause inflammation in your joints but can affect your jaw—making it hard to effectively keep your teeth clean—and can increase your risk for oral infections and ulcers, and deplete your salivation, which may lead to more cavities.

We wouldn't go so far as to say that having poor dental hygiene can definitively cause RA, but a few small-scale studies (like this 2018 one and this 2020 one) have linked certain oral microbiome markers to the later development of the disease. At the very least, if you have multiple other risk factors, periodontal disease could contribute to your eventual development of RA.

Stress

Yes, stress is a part of life for most of us, but if you're already predisposed to RA, high stress can lead to the onset of the disease, says Dr. Koval.

In other words, chronic stress or even one single extremely stressful event (like a death in the family or traumatic accident) can cause RA genes to be expressed in a person who has them thanks to their family history.

Illness or infection

Sickness happens even to the best of us, but most of the time we recover and move on.

However, sometimes your body triggers a heightened immune response during infection, sending a message to begin attacking the healthy tissue of the joints (this is more likely in people with the genetic disposition toward RA, but unfortunately it can happen to anyone).

Before you panic that the cold you just caught will give you RA, know that this is not a common cause. Bacteria is a typical culprit—think Lyme Disease—and some more serious viruses, like Epstein-Barr virus, parvovirus, hepatitis, and HIV are often associated with the onset of RA.

Environmental toxins

Dr. Maya warns that some environmental exposures, such as to silica, can increase your chances of developing RA. This is most commonly seen in people who work in industrial settings, like mines, quarries, and steel mills, where inorganic silica (a soil-based mineral) is often found in high amounts.

A 2020 review published in Safety and Health at Work suggests a clear link between occupational exposure to RA and a higher incidence of the disease, especially if the workers were also smokers.

Female hormones

Per Dr. Koval, the female to male ratio for developing RA is 10 to 1, making the disease much more common in women than in men. Why? Female hormones.

The frequent hormonal changes during a woman's reproductive years, including menstruation, pregnancy, and breastfeeding, and perimenopause, can often trigger the inflammatory response that leads to RA. In fact, one large Danish study from 2011 found that women were significantly more at risk for developing an autoimmune disorder in the first year after pregnancy, proposing that something about the state of being pregnant for nine months can trigger a systemic immune response.

Poor nutrition

There's no magic diet that will ensure you avoid RA, but we do know that obesity increases your likelihood of developing it. The Mayo Clinic points to both age and gender as contributing factors here, noting that RA is especially common in obese women under the age of 55.

The relationship between body fat and RA is linked, again, to inflammation. Body fat can cause your cells to produce more cytokines, a protein associated with the inflammatory response. This can speed up the onset of RA, leading to inflammation in your joints much sooner. It's also typical for RA patients who are obese to lose range of motion more quickly, per the Arthritis Foundation.

Can you prevent rheumatoid arthritis?

You can't "prevent" RA in the typical sense; genetically-speaking, there's nothing you can do to change whatever genes you've inherited, and even mitigating some of your other risk factors may not allow you to avoid the disease. Sometimes, RA just happens—when there are so many possible causes contributing to your overall risk, it's nearly impossible to say which one was to blame (or if you could have done something to prevent it).

That said, there are ways to adopt a healthy lifestyle that reduce your chances of developing RA, whether you carry the genes that cause it or not.

"Eat as healthy as you can—eat less pro-inflammatory foods, and limit sweeteners and red meats," says Dr. Koval. "And even reducing the amount of smoking you do can cause a delay in the presentation of RA symptoms."

In addition to your diet, Dr. Maya adds that it's important to maintain good dental hygiene and stress levels, since those are two other factors at least somewhat in your control.

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