Ingestion of capsaicin capsules induces symptoms in patients with non ulcer dyspepsia: Chemical hypersensitivity or hypervigilance?
Introduction: The ingestion of capsules containing capsaicin, the pungent ingredient of chili pepper, induces more intense upper GI sensations in patients with non ulcer dyspepsia (NUD) than in health, in patients with inflammatory bowel disease (IBD), peptic ulcer disease (PUD), and other GI disorders. Whether this is due to chemical hypersensitivity or hypervigilance is yet not clear.
Aims: 1) to further evaluate whether oral ingestion of capsaicin containing capsules ('capsaicin test') induces more symptoms in patients with NUD than in health and in patients with upper GI symptoms of other origin. 2) to determine whether in NUD patients the symptoms induced by the ingestion of capsaicin capsules are due to chemical hypersensitivity or hypervigilance.
Methods: N=200 outpatients (73 NUD, 26 IBD, 23 PUD, 36 irritable bowel syndrome (IBS) and 42 other diseases) and N=86 healthy controls swallowed a capsule containing 0,75mg capsaicin after an overnight fast. Subjects completed a graded questionnaire evaluating intensity of 9 different upper GI symptoms (5 grades per symptom) before and 30 minutes after capsule ingestion. Symptom scores were summarized and a score difference (score after minus score before capsule ingestion) was calculated; according to previous findings, a score difference >9 was considered as positive test. Additional N=20 healthy subjects and N=13 NUD patients who had a positive test received a second capsule containing placebo. NS=not significant.
Results: Score difference in NUD was 9.5±6.2, i.e. significantly higher than in PUD (1.9±5.0, p<0.001), IBD (4.5±4.7; p<0.01), IBS (5.2±4.9; p<0.05) and 'other GI disorders' (2.9±3.4; p<0.001), as well as healthy controls (6.5±4.3; p<0.001). 51% of patients with NUD had a positive test, 49% a negative test. The result of the capsaicin test was independent of the subgroup of NUD (pain or discomfort predominant). Healthy subjects (n=20) had a symptom score of 1.0±1.9 when receiving placebo and 2.5±2.1 after capsaicin. NUD patients (n=13) had a score difference of 2.0±1.7 after placebo (NS vs. health) and 15.8±2.6 after capsaicin. No patient had a positive test after placebo.
Conclusion: Capsaicin induces symptoms in patients with NUD due to chemical hypersensitivity rather than hypervigilance (no reaction to placebo). Chemical hypersensitivity discriminates functional disorders from healthy controls and patients with other upper GI disorders. The capsaicin test is a simple and non invasive method to detect a subgroup of functional dyspepsia with chemical hypersensitivity. Targeting the VR1 receptor might be a therapeutic option in a large subgroup of patients with functional dyspepsia.