Certain traits increase the risk of developing rheumatoid arthritis. Some of these traits are inherent and cannot be changed, such as genes, and others may be influenced by lifestyle changes, such as smoking.
While risk factors are known, rheumatoid arthritis is unpredictable. Having one or even several risk factors for RA does not guarantee an individual will get the disease. And while experts theorize there may be ways to prevent RA, getting RA is never an individual’s fault.
Sex and Age
Women are twice as likely to be diagnosed with rheumatoid arthritis than men. While RA can be diagnosed at any time, most people are diagnosed between 40 to 60 years of age.1
Genetic Predisposition to RA
A specific gene associated with rheumatoid arthritis, HLA-DR4, is found in 60% to 70% of Caucasians who have the disease. In contrast, it is only found in 30% of the general population.2
Genes alone are not the cause of rheumatoid arthritis. For example, studies of identical twins—who share all the same genes—have found that if one twin has RA there is only a 12% to 15% chance the other twin also has RA.1
Physicians typically do not order genetic tests when diagnosing rheumatoid arthritis.
People who grew up with abuse, neglect, or other household dysfunction may be more likely to develop an autoimmune disease. One research study3 found that children who experienced more than one stressful event or circumstance were twice as likely to develop rheumatoid arthritis or another rheumatologic disease.
Examples of traumatic childhood events include:
- Death of a parent or sibling
- Verbal abuse
- Sexual assault
- Parental divorce
- A parent with alcoholism
Environmental and Lifestyle Factors
Day-to-day habits seem to influence people’s risk of getting rheumatoid arthritis. The most established research in this area focuses on smoking, diet, and body weight.
Smoking and exposure to toxins
The greatest known environmental risk factor for rheumatoid arthritis is exposure to nicotine, particularly smoking.1
While the direct effect of smoking is not fully understood, it is believed that prolonged smoking plays a role in increasing the concentration of rheumatoid factor, which is an antibody (a type of protein molecule) that can be found in the blood. High levels of rheumatoid factor in the blood is one sign of RA.
The development of rheumatoid arthritis has been linked to drinking sugary sodas,10 and possibly to foods high in sugar and trans fats.
While there is a connection between diet and rheumatoid arthritis, scientists are still learning about the details. Diet may influence RA development and symptoms in one or more ways. For example, diet has the potential to affect:
- The gut microbiome, which influences immune system function and susceptibility to autoimmune disease11
- The cells of the immune system, which can release protein molecules that promote inflammation, called pro-inflammatory cytokines12-14
- The presence of excess fat tissue, which can contribute to inflammation and the development of autoimmune disease15
Using diet to decrease the risk of rheumatoid arthritis or reduce symptoms is becoming more common but remains an unproven strategy. In general, studies suggest that:
- Inflammation is triggered by consuming drinks and packaged foods that are high in sugar and trans fats10
- Inflammation may be decreased by a whole-foods, plant-based diet that emphasizes fruits, vegetables, and foods that are high in fiber and omega-3 fatty acids
Recommendations regarding specific foods can be conflicting and confusing. Certain foods affect people differently. For example, dairy foods may trigger RA inflammation in one person but not another.
In general, researchers have found that people who carry excess weight have a greater risk of developing rheumatoid arthritis.16-18 However, the results of one large study suggest that while excess weight increases the risk of developing RA for women, it may decrease the risk for men.19 More research is needed in this area.
Although environmental and lifestyle factors can influence the risk of getting RA, there is not a direct link. Most people who smoke, are overweight, and eat food high in sugar and trans fats will not get rheumatoid arthritis.
Disruption in Hormone Balance
Fluctuations in hormones may play a role in the development of rheumatoid arthritis and symptom severity. Researchers have found:
- RA symptoms subside in women during pregnancy, only to flare up again after the birth
- Women who enter menopause early (before age 40) may have an increased risk of developing seronegative RA20
The Gut Microbiome and Infection History
A body’s microbiome is a collection of microbes, such as bacteria and fungi, that live in the mouth, digestive tract, airway, and elsewhere. The body’s microbiome, particularly in the intestines or gut, can influence the development of RA.23-27
Current research shows:
- The gut microbiome affects overall health, including metabolism and immune system function
- The gut microbiome is seeded at birth, develops in early childhood, and is influenced throughout life by things like environment, diet, stress, exercise, and medications, particularly antibiotics
- A healthy gut microbiome includes a balanced, diverse array of thousands of microbiota species
- When gut microbiota species are out of balance (there are too much or too few of certain species), the risk for developing an autoimmune disease, such as RA, may increase
In addition, ongoing research is examining the link between bacterial and viral infections and the development of rheumatoid arthritis. Clinical research suggests there may be associations between RA and certain infections, such as gingivitis, the Epstein-Barr virus, and chronic hepatitis C.28-31
Although experts have identified possible links between microbes and RA, there is not enough evidence to point to clear cause and effect. More research is needed.