Rheumatoid arthritis is a devastating disease…painful, disabling, disfiguring. Though scientists know that it’s an autoimmune illness—a mistaken attack by the body on its own cells and tissues—they don’t know what triggers the disease. But now, a new study suggests that a particular type of physiological disturbance might set off rheumatoid arthritis—and, surprisingly, this disturbance doesn’t start in your joints. Instead, it may be happening in your gut. Here’s the connection…

GUT REACTION

Rheumatoid arthritis is quite complex because it develops in phases over many years. At some point, the level of autoantibodies (immune system proteins that target the body’s own tissues) jumps—due to some unknown triggering event—and then inflammation sets in and joint pain develops. Suspects for that triggering event have included cigarette smoke and periodontal disease…but researchers from New York University School of Medicine wanted to explore whether gut bacteria could be to blame.

Why did the researchers suspect that gut bacteria might be linked to arthritis? Animal studies have shown that mice that are specially bred to be at increased risk for rheumatoid arthritis can remain free from the disease as long as they remain in a sterile environment…but once they are exposed to certain species of bacteria sometimes found in the gut, they begin to develop joint inflammation.

Bacteria in the gut can also be found in the stool. So the researchers analyzed stool samples from people with newly diagnosed, untreated rheumatoid arthritis…from healthy people…from people with psoriatic arthritis (also an autoimmune disorder)…and from people with long-standing rheumatoid arthritis who were already being treated with immune-suppressing drugs.

What they found: Among people with new-onset, untreated rheumatoid arthritis, 75% carried an inflammatory species of gut bacteria called Prevotella copri (P. copri). This same bacteria was found in just 21% of the healthy people…38% of the psoriatic arthritis patients…and 12% of those who had been treated for chronic rheumatoid arthritis. Also, people with higher levels of P. copri had correspondingly lower levels of beneficial gut bacteria such as Bacteroides, which help control other pathogens.

The researchers were surprised that the prevalence of P. copri in patients who had been treated for chronic rheumatoid arthritis was so much lower than in new-onset patients. They hypothesized that P. copri needs an inflammatory environment to flourish…and that, with treatment for arthritis, the inflammation diminishes.

INFLAMMATION EXPLANATION

Next the researchers wanted to determine whether higher levels of P. copri would contribute to an inflammatory response (because, remember, rheumatoid arthritis is an inflammatory disease). So they fed the bacteria to some mice but not to others…then, two weeks later, they fed all these mice an inflammatory solution.

Results: The mice that had been given the P. copri experienced significantly more weight loss and intestinal tract damage—suggesting that P. copri creates an environment that supports inflammation in people who are genetically susceptible.

From mice to men: Of course, findings from animal studies aren’t always easily related to people, so human studies are needed to see whether an overgrowth of P. copri actually prompts the onset of rheumatoid arthritis in people. And it remains to be discovered exactly how arthritis-triggering signals from the gut might reach the joints. Most importantly, more research is needed to see whether correcting the balance of gut bacteria would prevent or delay the onset of rheumatoid arthritis or even help halt the disease’s progression.

For now, though, whether you have rheumatoid arthritis or are hoping to prevent it, it would be prudent to protect the normal environment of your own gut. For instance, consider increasing your intake of fiber-rich plant foods, especially asparagus, chicory, oats, onions, garlic, bananas, soy, peas and beans—these contain prebiotics, nondigestible food components that stimulate the activity of healthful bacteria. Also, ask a nutrition-oriented doctor whether it would be appropriate for you to take supplements of probiotics and/or digestive enzymes to keep your gut bacteria in balance.