Johann Hammer

Hypersensitivity for capsaicin in patients with functional dyspepsia

Abstract  The pathophysiology of functional dyspepsia is poorly understood, thus diagnostic and therapeutic options for this disease are limited. We assessed the relevance of a simple test for chemical hypersensitivity by applying an oral capsaicin load. After a preliminary dose‐finding study, 61 healthy controls and 54 functional dyspepsia patients swallowed a capsule containing 0.75 mg capsaicin. A graded questionnaire evaluated severity of symptoms before and after capsule ingestion; an aggregate symptom score was calculated by adding all symptom scores. Controls developed moderate symptoms (symptom score: 6.0 ± 4.1; median: 5.0). The 75% quartile (9.0) was considered the upper limit of normal. Functional dyspepsia patients had significantly higher symptom scores (10.0 ± 6.5) than controls. About 54% of functional dyspepsia patients tested positive; clinically this group was not different from the group testing negative besides being on average younger and suffering more from bloating. In additional 13 patients with functional dyspepsia who tested positive (symptom score: 15.8 ± 0.9), symptom response to placebo capsules (1.9 ± 0.6) was similar to controls. In reliability testing, the Cronbach α‐value of the capsaicin test was 0.86. The capsaicin test is a simple and non‐invasive method to detect a subgroup of functional dyspepsia with chemical hypersensitivity.

Characterization of sensations induced by capsaicin in the upper gastrointestinal tract

Abstract  Intraluminal capsaicin induces perception in the jejunum, but chemosensitivity of proximal gastrointestinal regions is unclear. Our aim was to evaluate the quality of perception induced by intraluminal capsaicin in different regions of the upper gastrointestinal tract. Healthy volunteers received either an oral tube for distension and capsaicin perfusion of the mid‐duodenum or jejunum or swallowed a capsule containing 0.75 mg capsaicin powder. Graded questionnaires evaluated quality and severity of sensations during distensions, capsaicin infusion and 30 min after ingestion of capsaicin capsules respectively. Duodenal capsaicin induced sensations at lower doses than jejunal capsaicin (P < 0.05). Most prominent sensations evoked by capsaicin infusion were pressure, cramps, pain and nausea; nausea and warmth were more intense during capsaicin infusion than distension (P < 0.05,for the duodenum and jejunum), pain was more intense during distension (P < 0.05, duodenum only). Gastric ingestion of capsaicin capsules mainly induced sensations of pressure, heartburn and warmth. Capsaicin application into the upper gastrointestinal tract reproducibly induced upper abdominal sensation. Qualitative features distinguished chemically from mechanically induced sensations, but both sensitivity for chemical and mechanical stimulation decreased along the intestine. Activation of chemical pathways could be a useful human pain model activating nociceptors apart from mechanical stimulation.

Diarrhea Caused By Carbohydrate Malabsorption

This article will focus on the role of the colon in the pathogenesis of diarrhea in carbohydrate malabsorption or physiologically incomplete absorption of carbohydrates, and on the most common manifestation of carbohydrate malabsorption, lactose malabsorption. In addition, incomplete fructose absorption, the role of carbohydrate malabsorption in other malabsorptive diseases, and congenital defects that lead to malabsorption will be covered. The article concludes with a section on diagnostic tools to evaluate carbohydrate malabsorption.

Effect of repeated, long term capsaicin ingestion on intestinal chemo- and mechanosensation in healthy volunteers

Abstract  Repeated ingestion of capsaicin over a prolonged period reduces symptoms in functional dyspepsia, but initially induces upper abdominal symptoms. Sensitizing chemonociception might be the cause for this initial effect of capsaicin. The aim was to evaluate the effect of prolonged capsaicin ingestion on duodenal chemo‐ and mechanonociception. Healthy subjects ingested capsules containing either 0.25 mg capsaicin tid (n = 8) or placebo (n = 8) for 28 days. Before (day 0) and after (day 29) capsule ingestion the duodenum was distended with a balloon and perfused with a capsaicin solution. Mechanically and chemically induced sensation was evaluated by a graded questionnaire. Aggregate perception scores were calculated. Perception scores during balloon distensions with 12 and 18 mmHg were significantly lower after 4 weeks capsaicin when compared to baseline (P < 0.05). Balloon volumes to induce first sensation (63 ± 14 mL (day 0) vs 92 ± 22 mL (day 29); P < 0.05) and discomfort (101 ± 12 mL vs 137 ± 22 mL; P = 0.05) where significantly higher after 4 weeks capsaicin application; balloon pressures to induce sensations were not significantly different. Intraluminal capsaicin application induced first sensation after 3.4 ± 1.5 min (day 0) and 7.5 ± 4.6 min (day 29) (P < 0.05) and discomfort after 15.9 ± 9.8 min and 22.4 ± 7.3 min (P < 0.05). The quality of perception was not altered by repeated capsaicin ingestion. In the placebo group, mechano‐ and chemonociception remained unaltered at day 29. Four weeks ingestion of capsaicin desensitized both chemonociceptive and mechanonociceptive pathways in healthy volunteers. Symptom reduction after prolonged treatment with capsaicin in dyspeptic patients might be attributed to a dual desensitizing effect of capsaicin on chemonociceptors and mechanonociceptors.

A placebo-controlled trial of an oral capsaicin load in patients with functional dyspepsia.

Background  The pathophysiology of functional dyspepsia is poorly understood. Visceral hypersensitivity may play a key role. We studied a previously validated test to assess chemical hypersensitivity in functional dyspepsia by applying an oral capsaicin load.

Characterization of a reproducible gastric pain model using oral capsaicin titration in healthy volunteers.

Background  Sensory sensitization is one of the main pathophysiological hypotheses in functional gastrointestinal disorders (FGIDs). As sensitization may affect various sensory modalities, we aimed to develop a reproducible gastric pain model utilizing polymodal pathways for use in functional and other pain disorders.

Clinical characteristics of functional dyspepsia depending on chemosensitivity to capsaicin

Augmented chemosensitivity to capsaicin has been demonstrated in approximately half of functional dyspepsia (FD) patients.

Reply to Drs. Pellicano and Ford

>10 and a negative LR of <0.1 are generally considered as useful for ruling in or ruling out a disease [5]. In fact, the performance of the oral capsaicin test in predicting FD was only slightly better than that of the Rome III criteria themselves in a large Canadian study [6]. In this study, when the Rome III criteria were applied prospectively to 1452 unselected patients with upper GI symptoms undergoing endoscopy their sensitivity, specificity, and positive and negative LRs, in identifying FD, were reported as 61%, 69%, 1.94, and 0.57, respectively. In addition, and for reasons that are unclear, rather than testing the performance of the oral capsaicin test in an unselected group of patients undergoing endoscopy for upper GI symptoms, the author tested its performance in a mixed group of patients with upper GI symptoms, such as dyspepsia and gastro-esophageal reflux, as well as patients with known lower GI disorders, including IBS and inflammatory bowel disease, and a group of patients with other GI and non-GI disorders. It is unclear why these other two patient groups were included and, given that patients with lower GI and non-GI diseases are probably less likely to demonstrate a positive test, their inclusion is likely to have enhanced the modest performance of the oral capsaicin test. This is akin to spectrum bias, seen in case-control studies, where by using two extreme groups of patients the study design often omits mild cases that are more difficult to diagnose, leading to an overestimation of the diagnostic performance of the test being examined, compared with studies that use a true unselected clinical cohort [7]. In summary, although the performance of the oral capsaicin test in this single center study recruiting a mixed group of patients with upper GI, lower GI, and nonGI disorders was encouraging, it needs to be replicated in large unselected cohorts of patients presenting for endoscopy with upper GI symptoms.

Gastric administration of garlic powder containing the trpa1- agonist allicin induces specific epigastric symptoms and gastric relaxation in healthy subjects

TRPA1 is an excitatory ion channel and is involved in sensory processes including thermal nociception and inflammatory pain. The allicin in garlic is a strong activator of the TRPA1 channel.

Correction to: Relationship Between Abdominal Symptoms and Fructose Ingestion in Children with Chronic Abdominal Pain

The original version of this article unfortunately contained an error in a couple of reference citation in Discussion Section, paragraph 6. The reference citation number should be changed from [6] to [9] in the below sentences so that it reads.