Why Do Plant-Based Diets Help Rheumatoid Arthritis?
•By: Dr. Michael Greger
DR. MICHAEL GREGER Is a founding member and Fellow of the American College of Lifestyle Medicine, Michael Greger, MD, is a physician,, and internationally recognized speaker on nutrition, food safety, and public health issues. l. He is a graduate of Cornell University School of Agriculture and Tufts University School of Medicine. Currently Dr. Greger serves as the public health director at The Humane Society of the United States.
Rheumatoid arthritis is a chronic systemic autoimmune disease affecting millions. It is characterized by persistent pain, stiffness and progressive joint destruction leading to crippling deformities, particularly in the hands and feet. What can we do to prevent and treat it?
In a famous 13-month-long randomized controlled trial of plant-based diets for rheumatoid arthritis, patients were put on a vegan diet for three and a half months and then switched to an egg-free lacto vegetarian diet for the remainder of the study. Compared to the control group (who didn’t change their diet at all), the plant-based group experienced significant improvements starting within weeks.
Their morning stiffness improved within the first month, cutting the number of hours they suffered from joint stiffness in half. Their pain level dropped from 5 out of 10 down to less than 3 out of 10. Disability levels dropped, subjects reported feeling better, they had greater grip strength, fewer tender joints, less tenderness per joint and less swelling. They also had a drop in inflammatory markers in their blood, such as sedimentation rate, C-reactive protein and white blood cell count. And as a bonus they lost about 13 pounds and kept most of that weight off throughout the year.
The question is why. What does diet have to do with joint disease?
Rheumatoid arthritis is an autoimmune disease in which our own body attacks the lining of our joints. There’s also a different autoimmune disease called rheumatic fever, in which our body attacks our heart. Why would it do that? It appears to be a matter of friendly fire.
Rheumatic fever is caused by strep throat, which is itself caused by a bacterium that has a protein that looks an awful lot like a protein in our heart. When our immune system attacks the strep bacteria, it also attacks our heart valves, triggering an autoimmune attack by “molecular mimicry.” The protein on the strep bacteria is mimicking a protein in our heart so our body gets confused and attacks both. That’s why it’s critical to treat strep throat early to prevent our heart from getting caught in the crossfire
Researchers figured that rheumatoid arthritis might be triggered by an infection as well. A clue to where to start looking was the fact that women seem to get it three times more frequently than men. What type of infection do women get more than men? Urinary tract infections (UTIs). So researchers started testing the urine of rheumatoid arthritis sufferers and, found a bacterium called Proteus mirabilis. Not enough to cause symptoms of a UTI, but enough to trigger an immune response. And indeed, there’s a molecule in the bacterium that looks an awful lot like one of the molecules in our joints.
The theory is that anti-Proteus antibodies against the bacterial molecule may inadvertently damage our own joint tissues, eventually leading to joint destruction. Therefore, interventions to remove this bacteria from the bodies of patients, with consequent reduction of antibodies against the organism, should lead to a decrease in inflammation.
Urinary tract infections originate from the fecal flora. The bacteria crawl up from the rectum into the bladder. How might we change the bugs in our colons? By changing our diet.
Some of the first studies published more than 20 years ago to fundamentally shift people’s gut flora were done using raw vegan diets, figuring that’s about as fundamental a shift from the standard Western diet as possible. Indeed, within days researchers could significantly change subjects’ gut flora.
When researchers put rheumatoid arthritis sufferers on that kind of diet, they experienced relief and the greatest improvements were linked to greatest changes in gut flora. The diet was considered so intolerable, though, that half the patients couldn’t take it and dropped out, perhaps because they were trying to feed people things like “buckwheat-beetroot cutlets” buttered with a spread made out of almonds and fermented cucumber juice.
Thankfully, regular vegetarian and vegan diets work too, changing the intestinal flora and improving rheumatoid arthritis. However, we didn’t specifically have confirmation that plant-based diets brought down anti-Proteus antibodies until 2014. Subjects that responded to the plant-based diet showed a significant drop in anti-Proteus mirabilis antibodies compared to the control group. Maybe it just dropped immune responses across the board? No, antibody levels against other bugs remained the same, so the assumption is that the veg diet reduced urinary or gut levels of the bacteria.
A shift from an omnivorous to a vegetarian diet has a profound influence on the composition of urine as well. For example, those eating vegetarian had higher levels of lignans in their urine. Up until now, it was thought that they only protected people from getting cancer, but we now know lignans can also have antimicrobial properties. Perhaps they help clear Proteus mirabilis from the system. Either way, these data suggest a new type of therapy for the management of rheumatoid arthritis: anti-Proteus measures including plant-based diets.
I have to admit I had never even heard of Proteus mirabilis. That’s why I love doing work—I learn as much as you do!
Michael Greger, M.D.