Eligibility Criteria:
Inclusion Criteria:
* Voluntary acceptance to participate in the study, Being within the age range of 18-64 years, Having a diagnosis of rheumatoid arthritis according to the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) classification criteria and belonging to the seropositive rheumatoid arthritis subgroup, Being in the active phase of rheumatoid arthritis according to the DAS-28 CRP or DAS-28 ESR disease activity score, Having a disease duration of at least 1 year, Not having previously undergone any dietary treatment specific to rheumatoid arthritis, Not using any dietary supplements other than calcium and vitamin D3 supplementation (e.g., 1000 mg calcium, 880 IU vitamin D3) recommended by the physician for patients using glucocorticoids and folic acid supplementation (10 mg weekly) recommended for patients using methotrexate, Having stable use of disease-modifying anti-rheumatic drugs (≥3 months), corticosteroids (≥4 weeks), and nonsteroidal anti-inflammatory drugs (≥10 days) before starting the DASH diet treatment, with a daily oral corticosteroid dose not exceeding 12.5 mg of prednisolone, Not having a diagnosis of eating disorders, Not being pregnant or breastfeeding, Not using banned substances, Having no intellectual disability, Having no allergy and/or intolerance to the foods included in the DASH diet
Exclusion Criteria:
* Not voluntarily agreeing to participate in the study, Not being within the age range of 18-64 years, Not having a diagnosis of rheumatoid arthritis according to the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) classification criteria, and not belonging to the seropositive rheumatoid arthritis subgroup, Being in remission according to the DAS-28 CRP and DAS-28 ESR disease activity scores, Having a disease duration of less than 1 year, Having previously undergone any dietary treatment specific to rheumatoid arthritis, Using any dietary supplements other than calcium and vitamin D3 supplementation (e.g., 1000 mg calcium, 880 IU vitamin D3) recommended by the physician for patients receiving glucocorticoid therapy and folic acid supplementation (10 mg weekly) recommended for patients using methotrexate, Having changes in disease-modifying anti-rheumatic drugs usage within less than 3 months, corticosteroids within less than 4 weeks, and nonsteroidal anti-inflammatory drugs within less than 10 days before starting the DASH diet treatment, having a daily oral corticosteroid dose exceeding 12.5 mg of prednisolone, Having a diagnosis of eating disorders, Being pregnant or breastfeeding, Using banned substances, Having intellectual disability, Having any allergy and/or intolerance to the foods included in the DASH diet.