Juvenile idiopathic arthritis (JIA) is a chronic autoimmune disorder, characterized by chronic idiopathic joint inflammation in children under sixteen years of age. Emerging evidence suggests that food allergens- particularly cow’s milk proteins may modulate inflammatory pathways, and that their elimination could potentially ameliorate disease activity. This study aimed to evaluate through a randomized controlled clinical trial whether eliminating cow’s milk protein from the diet influences disease activity and symptom severity in children with JIA. In this randomized controlled trial, 120 children with controlled juvenile idiopathic arthritis (JIA) receiving stable standard therapy were randomly allocated to either a cow’s milk protein–free diet (intervention group, n = 60) or an unrestricted diet (control group, n = 60) for one month. Disease activity was assessed at baseline and post-intervention using subjective measures (patient- and physician-reported Visual Analog Scale VAS) and objective parameters, including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), active joint count, morning stiffness duration, fever. Compared with baseline, the intervention group demonstrated statistically significant improvements in multiple outcomes, including patient VAS (2.9 ± 1.9 to 1.7 ± 1.4; P < 0.001), physician VAS (2.5 ± 1.8 to 1.6 ± 1.3; P < 0.001), ESR (14.6 ± 13.7 to 9.4 ± 7.3 mm/hr; P < 0.001), CRP (7.3 ± 13.7 to 2.5 ± 3.6 mg/dL; P = 0.011), morning stiffness duration (6.1 to 0.6 min; P = 0.002), active joint count (0.55 to 0.11; P < 0.001), and Disease Activity Score (5.53 ± 4.44 to 3.0 ± 2.6; P < 0.001). In contrast, the control group exhibited only minor or non-significant changes. In children with well-controlled JIA, a cow’s milk protein–free diet was associated with modest short-term improvements in pain and disease activity. These findings suggest a potential adjunctive benefit alongside standard therapy, but the short duration, low baseline disease activity, and reliance on parental self-report warrant cautious interpretation. The protocol of this clinical trial has been registered in the Iranian Clinical Trial Registration Center (registration code: IRCT20241230064216N1). Registered 28 April 2025, available from https://irct.behdasht.gov.ir/search/result?query=IRCT20241230064216N1, and ethical approval was obtained from the Ethics Committee of Shahid Beheshti University of Medical Sciences, registered 10 November 2024 (Ethics Code: IR.SBMU.MAP.REC.1403.531).
Karouei et al. (2026) studied this question.