Plant-Based Diet for Patients With Rheumatoid Arthritis

The goal of this clinical trial is to evaluate the effect of a plant-based diet (PBD) intervention in adults with Rheumatoid Arthritis (RA) on disease activity. The investigators hypothesize that if patients with RA follow a 100% PBD over a 16-week period it will lead to improvements in: \- Disease activity (measured by DAS28), including reduction in symptoms and overall improvements in health-related quality of life. The effects of the PBD will be compared to a habitual diet, that includes no dietary changes. Participants in the intervention group will: * Receive weekly delivery of food boxes which include plant-based food items * Receive a daily multivitamin supplement * Receive continuous dietetic guidance * Participate in a practical cooking class to get an introduction to a PBD * Participate in three online supervisions throughout the intervention period Participants in the control group will follow the same plan for the project visits at the hospital but will be restricted to continue their habitual diet. Thus, not performing any dietary changes.

Rheumatoid Arthritis (RA) is a chronic, autoimmune disease, requiring lifelong medical treatment. Evidence has suggested that supporting patients with RA to take an active role in their management of their disease can improve the patients' overall health and quality of life. In addition, patients often ask for support to identify effective ways to reduce symptoms, which include lifestyle changes, of which nutrition may be important. From a patient perspective, the lack of consistent evidence on nutrition also affects patients' choices regarding diet. Patients with RA have expressed that their is insufficient guiding regarding dietary choices. Hypotheses about the effect of various diets on disease activity in RA have been suggested, hence, the influence of pro-inflammatory and anti-inflammatory ingredients have been clinically investigated, however, with very limited studies investigating the effect of a 100% plant-based diet (PBD) on disease activity in RA. The objective of this study is to investigate if 16-weeks of PBD reduces disease activity and RA-related symptoms, and improves cardio-metabolic health, physical function, mental health, sleep quality and health-related quality of life (HRQoL) in patients with RA. Thus, in this RCT the patients in the intervention group will be instructed to adhere to a 100% PBD and without changing e.g., exercise habits. The 16-week intervention consists of * Weekly delivery of food boxes including plant-based food items for the entire household. Including various different recipes for a balanced PBD. * A daily multivitamin supplement. * Continuous dietetic guidance either in person, by phone or e-mail. * The patients will participate in a practical cooking class to get an introduction to a PBD. Here they will be in groups of approx. 5-8 patients. * Throughout the intervention period the patients will in addition participate in three online supervisions with the same group they were together with in the cooking class. * The patients will register their food and drink intake two days before each project visit. The control group will be asked to maintain habitual diet. At study end, they will receive the same recipes as the intervention group. All participants, despite group allocation will undergo the same outcome assessments at each project visits (baseline, week 6, week 12, week 16 (end of intervention), and a follow-up visit 12 months after end of intervention: The following data will be collected: Baseline: * Assessment of swollen and tender joints * Ultrasound of joints * Patient-reported outcomes (questionnaires) * Blood samples * Urine samples * Feces samples * Blood pressure * Anthropometrics (body composition) * Dietary records Week 6 and 12: * Blood samples * Urine samples * Dietary records Week 16: * Assessment of swollen and tender joints * Ultrasound of joints * Patient-reported outcomes (questionnaires) * Blood samples * Urine samples * Feces samples * Blood pressure * Anthropometrics (body composition) * Dietary records 1-year follow-up: * Assessment of swollen and tender joints * Ultrasound of joints * Patient-reported outcomes (questionnaires) * Blood samples * Urine samples * Feces samples * Blood pressure * Anthropometrics (body composition) * Dietary records