The study, published in the journal Frontiers in Nutrition, reviewed clinical trials and observational studies and found strong and consistent evidence that a plant-based dietary pattern can reduce inflammation and improve symptoms associated with the disorder.
The researchers, from the Physicians Committee for Responsible Medicine, highlight four ways a plant-based diet may be effective: the high fibre helping to reduce inflammation, the high fibre and low fat intake helping to reduce pain and swelling, the less calorie-dense foods helping to maintain a lower BMI and the high fibre diet promoting growth of healthy gut bacteria.
Previous studies have found that a plant-based diet may be protective against hypothyroidism, hyperthyroidism, and multiple sclerosis. This review adds to the evidence that diets rich in fruits, vegetables, whole grains, and legumes may be beneficial for autoimmune conditions.
Researchers note a 2015 study found that participants randomised to a two-month plant-based dietary intervention experienced reductions in inflammatory scores, when compared to those eating diets higher in fat and animal products.
Other studies have found that diets high in fat and processed meat are associated with inflammatory markers, including C-reactive protein (CRP). Plant-based diets and high fibre diets have been associated with lower CRP levels.
Pain and swelling
The review points to a randomised clinical trial that looked at the effects of a low-fat vegan diet on people with moderate-to-severe RA which found that after just four weeks on the diet, participants experienced significant improvements in morning stiffness, RA pain, joint tenderness, and joint swelling.
The review authors suggest that plant-based diets are typically low in fat and high in fibre, which can reduce inflammation and decrease pain and swelling.
Studies reviewed found that excess body weight increases the risk for developing RA and decreases the likelihood of remission if RA is already present.
A 2018 analysis found that RA patients who lost more than 5 kilograms of body weight were three times more likely to experience improvements than those who lost less than 5 kilograms.
Some studies suggest that the microbiome may play a key role in RA and inflammation. The authors note that high-fiber plant-based diets can alter the composition of gut bacteria and increase bacterial diversity, which is often lacking in RA patients.
Co-author Hana Kahleova, MD, PhD, director of clinical research for the physicians committee says: "A plant-based diet comprised of fruits, vegetables, grains, and legumes may be tremendously helpful for those with rheumatoid arthritis.
"This study offers hope that with a simple menu change, joint pain, swelling, and other painful symptoms may improve or even disappear."
Source: Frontiers in Nutrition
Authors: Alwarith. J., et al
"Nutrition Interventions in Rheumatoid Arthritis: The Potential Use of Plant-Based Diets. A Review"