The researchers set out to examine the impact of different infections on the risk of rheumatoid arthritis in nearly 6,500 individuals in south and central Sweden. Of the sample, 2,831 had been newly diagnosed with rheumatoid arthritis and the remaining 3,570 randomly selected matched participants were healthy.
Participants were asked if they have experienced any gut, urinary tract, or genital infection within the last two years. They were also asked if they have had an inflamed prostate or had antibiotic treatment for sinusitis, tonsillitis or other throat infection, or pneumonia during this time.
Gut, urinary tract, and genital infections within the preceding two years were associated with a significantly lower risk of developing rheumatoid arthritis – an impressive 29 percent, 22 percent, and 20 percent, respectively. And having all three types of infection in the preceding two years was linked to a 50 percent lower risk, after adjusting for influential factors.
Recent infections did not impact the risk of rheumatoid arthritis, but having gut, urinary tract, or genital infections within the last two years appeared to have the strongest influence on rheumatoid arthritis.
The research was observational, so it cannot assert a cause-and-effect relationship, but the researchers said their findings “are particularly interesting in light of emerging data, implicating that the microbiome in the gut may play a role in rheumatoid arthritis pathogenesis.”
Rheumatoid arthritis and urinary tract infections: Connection in women
Rheumatoid arthritis is far more common among women compared to men, prompting researchers to look at the role of infections in the heightened risk of rheumatoid arthritis. One type of infection, largely common among women, is urinary tract infections.
When researchers tested the urine of people with rheumatoid arthritis, they detected a similar protein found in the lining of the joints. The body develops antibodies to fight off the infection, but apparently these also attack the lining of the joints.
Other studies have found that a plant-based diet could improve rheumatoid arthritis, but the reason behind it was not clear. The researchers suggest this style of eating feeds into good bacteria of the colon, meaning, more good bacteria can combat bad bacteria.