The goal of this clinical trial is to test in Rheumatoid arthritis. The main question it aims to answer are:

• To verify the effect of dietary fiber supplementation on reducing the level of inflammation;
• To verify the effect of dietary fiber supplementation on improving disease activity and quality of life in patients with rheumatoid arthritis .To verify the effect of dietary fiber supplementation on regulating the production of anti-inflammatory short-chain fatty acid in the gut of patients with rheumatoid arthritis.

The experimental group was supplemented with dietary fiber for 12 weeks, and the control group was fed with the Mediterranean diet. Before and after the intervention, 1 tube of 3ml blood and 1 soybean-sized stool were taken and a questionnaire was made

Rheumatic arthritis (RA) is caused by chronic inflammation and joint injury caused by imbalance of pro-and anti-inflammatory mediators in the joints. Studies have shown that dietary fiber (DF) can be fermented by gut bacteria into anti-inflammatory short-chain fatty acid that may reduce joint inflammation, relieve symptoms and improve quality of life. The subjects were Randomized controlled trial to supplement DF12W individually, the intervention group to supplement DF12W, and the control group to supplement DF12W with routine diet, the differences of disease activity (DAS28 score) , inflammatory markers (TNF-a, IL-6, Mir-146a, Treg, ESR, CRP, etc.) and quality of life (SF-36) between the two groups were compared. The changes of intestinal flora were examined to verify the hypothesis. This study laid a good scientific foundation for dietary recommendation of RA patients.

Inclusion Criteria:

• Patients diagnosed with rheumatoid arthritis according to the 2010 ACR/EULAR classification criteria, with a course of ≥ 2 years, and no changes in anti rheumatic drugs within 8 weeks prior to intervention;
• Age: 18-75 years old;
• DAS28-ESR ≥ 2.6 points, and fully controlled and treated with medication during screening visits;
• Sign an informed consent form and be able to complete the experiment according to the protocol.

Exclusion Criteria:

• Patients with mental illness, cognitive impairment, severe heart, lung, brain failure, serious complications, pregnancy, or life-threatening diseases;
• Patients with severe visual or auditory impairment and inability to understand research information;
• During the past 8 weeks of treatment with disease modifying anti rheumatic drugs (DMARDs), patients with food intolerance, allergies, and unwillingness to consume the intervention food in the study;
• In the past 10 years, there has been a history of tumors and eating disorders (such as neurogluttony, anorexia, binge eating, etc.);
• Participated in other intervention studies in the past three months.

Researchers set blinding to reduce implementation bias