Research has looked at the connection between the health of this microbiome and various diseases, such as multiple sclerosis, type 1 diabetes, and depression. And recently, a study published in September 2021 in Genome Medicine found a possible connection between a rheumatoid arthritis (RA) patient’s prognosis and their gut microbes. “This is the first study to date that uses gut microbiome data to predict clinical improvement in rheumatoid arthritis disease activity independent of the initial measurement of their condition or prior treatment,” said Jaeyun Sung, PhD, a co-senior author of the study, in a press release. Dr. Sung is a computational biologist within Mayo Clinic’s Center for Individualized Medicine in Rochester, Minnesota.
What Is Rheumatoid Arthritis?
An autoimmune disorder, RA is chronic inflammation of the joints and other body systems that occurs when the body’s immune system attacks its own healthy tissues. It can cause pain, swelling of the joints, and erosion of bone. Affecting some 1.5 million people in the United States, according to the National Institutes of Health (NIH), RA has no known cure, and its cause isn’t completely understood. Risk factors include family history, exposure to environmental triggers such as pollution, chemicals, or secondhand smoke, hormonal changes in women, and smoking.
What’s the Gut Got to Do With Rheumatoid Disease?
For the gut microbiome to function effectively, it needs to be balanced and diverse. “However, American gut microbiomes have become lacking in diversity, probably due to our diet, overuse of antibiotics, and other environmental factors,” says Maria Gloria Dominguez-Bello, PhD, professor of microbiome and health at the Rutgers School of Environmental and Biological Sciences in New Brunswick, New Jersey. A study published in April 2016 in Genome Medicine found that people with RA had less gut diversity than people who were disease-free. The good news is that researchers hope to one day be able to identify those people at higher risk for RA by looking at their gut bacteria and either start treatment earlier (which is known to improve prognosis) or to potentially modify the gut microbiome in order to improve disease outcomes.
What the Latest Research Shows
The Mayo Clinic researchers wanted to see if gut microbiota could be used as a prognostic marker; that is, to identify patients who, irrespective of their treatments, would either not improve or worsen over the course of time. The research team looked at stool samples 6 to 12 months apart from patients with later stage RA. Disease activity in these patients was also measured at the same time, in order to assess which patients achieved clinical improvement of the disease activity index and which did not. “We did identify that there were certainly different biome traits of people who eventually improved and those who didn’t. Diversity was part of the profile in these studies but not all of it: There were certain specific microbial taxa, such as Coprococcus, Bilophila, and Eubacterium, that were associated with that improvement. And we did some deeper profiling that identified biochemical pathways within the microbes that were associated with a likelihood of improvement. Those are important pathways to consider in further investigation of prognostic signatures,” says John M. Davis III, MD, a clinical rheumatologist at Mayo Clinic with a specialty interest in inflammatory arthritis. Dr. Davis is co-senior author of the study. He adds that “in the future, we may be able to use information gleaned from studies of gut microbial profiles and microbial biochemical pathways to predict how a patient will look in terms of their disease state even as far out at least as 6 to 12 months. This study suggests that there may be new targets for treatments based on the gut microbiome, and perhaps the novel treatments could target the adverse profiles of the guts, which could be helpful in improving response to our therapies.”
Specific Strains of Bacteria That May Affect RA
Research has previously shown a link between RA and the bug Prevotella copri. A study published in the journal eLife found that the intestines of 75 percent of people with early, untreated rheumatoid arthritis had this bacterium in their intestines compared with 12 percent of people with chronic, treated rheumatoid arthritis. The theory is that this bacteria crowds out beneficial microbiota that fight inflammation or itself promotes inflammation. Another study, published in April 2017 in Arthritis & Rheumatology, examined whether the overexpansion of Prevotella copri in the gut has the potential to affect immune cell functions, contributing to the development of RA. Study authors found that there is “evidence for immune relevance of P. copri in RA.” At this point, experts can’t claim that P. copri causes RA, but the research provides an intriguing path for future study, according to an article published in November 2019 in the Journal of Clinical Medicine. A different strain of the bacteria, Prevotella histicola, may actually decrease symptoms and disease progression, according to research done by Mayo Clinic’s Center for Individualized Medicine, published in April 2016 in Genome Medicine. Mice who were given the bacteria saw a delay in the disease and a reduction in the amount of cytokines (proteins that affect the immune system) in their system. “The question is, can this bacteria by itself be doing it? If it is, can we prevent arthritis?” says that study’s lead author, Veena Taneja, PhD, an immunologist Mayo Clinic.
Eating for a Healthy Microbiome
“It has been very challenging to modify the gut microbiome based on diet,” says Davis. Ideally, through understanding the relationships between an individual’s genetics and their own microbiome, healthcare providers might eventually be able to recommend individualized dietary guidelines that can improve RA. “Additionally,” adds Davis, “we hope that prebiotics [nondigestible food ingredients that promote the growth or activity of probiotics in the colon] may foster a healthier microbiome constituency, or perhaps probiotics [microorganisms in the digestive tract that promote digestion, support immunity, and manage inflammation] may be helpful in modulating the factors to improve the disease state." Davis notes that a lot of work still needs to be done to support that hypothesis and to develop individualized RA treatment strategies based on factors related to the gut microbiome. While definitive connections between the gut microbiome and RA have yet to be discovered, you can adopt a diet that promotes a balanced and diverse level of gut bacteria. Foods to eat include:
Fermented Foods
Sauerkraut, kimchi, miso, tempeh, fermented tofu, pickles, and pickled items such as pickled beets, radish, garlic, and cucumbers. During the fermentation process, bacteria predigest these foods, making some nutrients easier to absorb, according to a consensus statement by the International Scientific Association for Probiotics and Prebiotics published in January 2021 in Nature Reviews Gastroenterology & Hepatology. The probiotic bacteria then join your gut microbiome when you eat these foods.
Dairy
“Diets rich in lactose-containing food — fat-free milk, yogurt, and the like — are usually very beneficial for their bacterial content,” says Jonathan Krant, MD, medical director of rheumatology at Marietta Memorial Hospital in Marietta, Ohio.
Probiotic Supplements
There is no one-size-fits-all probiotic supplement, says Bonnie Taub-Dix, RDN, the author of Read It Before You Eat It. “What works for one person may not work for the next. Try one for a month and see how you feel. If you don’t get any relief or if you are getting a bad reaction, discontinue and try another kind.” If you want to make sure that contents are as advertised, look for a U.S. Pharmacopeial Convention (USP) verification label.
High-Fiber Foods
Fresh fruit and veggies and whole grains protect against infection and prevent bacteria from eating your stomach lining, according to research published in November 2016 in the journal Cell.
Anti-Inflammatory Foods
While there is no one specific food plan to follow for inflammatory arthritis, Dr. Krant recommends a diet rich in omega-3 fatty acids. Per the NIH, these healthy fats can be found in:
Cold-water fatty fish like salmon, trout, and fresh tunaWalnuts, flaxseed, and chia seedsPlant oils such as flaxseed, soybean, and canola oils
Certain brands of eggs, cereal, yogurt, juices, milk, and soy drinks have been fortified with omega-3s; check labels.
