Julianne McNeill, Gael Mearns, Rebecca Grainger, Caryn Zinn
ABSTRACT Background Individuals with rheumatoid arthritis (RA) often ask whether dietary changes or food exclusions can reduce symptoms. The Autoimmune Protocol (AIP) diet, an elimination‐based approach, is popular on social media, with anecdotal reports of benefit, but lacks clinical evaluation in RA. Objectives To assess the feasibility and effectiveness of an AIP diet on patient‐reported outcomes (PROs) in adults with RA. Methods In this single‐arm, open‐label pilot study, nine adults with RA followed their usual diet for 4 weeks and then an 8‐week AIP diet in a free‐living context. Weekly PRO measures included the Routine Assessment of Patient Index Data 3 (RAPID3) and RA Impact of Disease (RAID) as primary outcomes. Secondary outcomes included 3‐day weighed food records and biometric measurements (weight and waist circumference) collected at baseline and every 4 weeks. Adherence and ease of implementation were recorded weekly. Results Nine participants (7 females, 2 males, aged 40–63 years) completed the intervention. From baseline to end week 12, mean RAPID3 scores decreased from 2.73/10 (range 0.2–5.37) to 0.99 (0–2.5). Four participants demonstrated a clinically meaningful reduction and three others reached remission from low disease activity. Mean RAID scores decreased from 3.13/10 (0.1–6.35) to 1.02 (0–2.96). Fatigue, sleep and pain improved. Mean body mass index reduced from 26.3 kg/m 2 to 24.5 kg/m 2 . The diet was feasible with high adherence. Conclusions An 8‐week AIP diet was associated with improvements in PROs in seven of nine participants. These pilot findings support further controlled trials to confirm efficacy and explore mechanisms as a potential adjunct therapy for RA. Trial Registration Number ACTRN12624001391561. https://www.anzctr.org.au/ACTRN12624001391561.aspx