Masked bolus gluten challenge low in FODMAPs implicates nausea and vomiting as key symptoms associated with immune activation in treated coeliac disease.

Background In patients with coeliac disease, FODMAPs in gluten-containing foods, and participant anticipation of a harmful ('nocebo') effect, may contribute to acute symptoms after gluten challenge. Aim To establish acute gluten-specific symptoms linked to immune activation in coeliac disease Methods We included 36 coeliac disease patients on a gluten-free diet receiving placebo in the RESET CeD trial. Double-blind, bolus vital wheat gluten (similar to 6-g gluten protein) and sham challenges low in FODMAPs were consumed 2 weeks apart. Assessments included daily Coeliac Disease Patient Reported Outcome (CeD PRO) symptom scores (0-10), adverse events and serum interleukin-2 (baseline and 4 hours). Results Median CeD PRO score for nausea increased most (sham: 0 vs gluten: 5.5; P < .001). Apart from tiredness (1 vs 4, P = .005) and headache (0 vs 2, P = .002), changes in other symptoms were small or absent. Only nausea increased significantly in occurrence with gluten (11% vs 69%, P < .001). Without nausea, only tiredness and flatulence were common after gluten. Nausea (6% vs 61%, P < .001; median onset: 1:34 hours) and vomiting (0% vs 44%, P < .001; 1:51 hours) were the only adverse events more common with gluten than sham. Interleukin-2 was always below the level of quantitation (0.5 pg/mL) at baseline, and after sham. Interleukin-2 was elevated after gluten in 97% of patients (median fold-change: 20), and correlated with severity of nausea (r(s) = .49, P = .0025) and occurrence of vomiting (P = .0005). Conclusions Nausea and vomiting are relatively specific indicators of acute gluten ingestion, and correlate with immune activation. IBS-like symptoms without nausea are unlikely to indicate recent gluten exposure.