Abdominal distension after eating lettuce: The role of intestinal gas evaluated in vitro and by abdominal CT imaging

Abstract

BackgroundSome patients complain that eating lettuce, gives them gas and abdominal distention. Our aim was to determine to what extent the patients' assertion is sustained by evidence.MethodsAn in vitro study measured the amount of gas produced during the process of fermentation by a preparation of human colonic microbiota (n = 3) of predigested lettuce, as compared to beans, a high gas‐releasing substrate, to meat, a low gas‐releasing substrate, and to a nutrient‐free negative control. A clinical study in patients complaining of abdominal distention after eating lettuce (n = 12) measured the amount of intestinal gas and the morphometric configuration of the abdominal cavity in abdominal CT scans during an episode of lettuce‐induced distension as compared to basal conditions.Key ResultsGas production by microbiota fermentation of lettuce in vitro was similar to that of meat (P = .44), lower than that of beans (by 78 ± 15%; P < .001) and higher than with the nutrient‐free control (by 25 ± 19%; P = .05). Patients complaining of abdominal distension after eating lettuce exhibited an increase in girth (35 ± 3 mm larger than basal; P < .001) without significant increase in colonic gas content (39 ± 4 mL increase; P = .071); abdominal distension was related to a descent of the diaphragm (by 7 ± 3 mm; P = .027) with redistribution of normal abdominal contents.Conclusion and InferencesLettuce is a low gas‐releasing substrate for microbiota fermentation and lettuce‐induced abdominal distension is produced by an uncoordinated activity of the abdominal walls. Correction of the somatic response might be more effective than the current dietary restriction strategy.

Gastrointestinal Contributions to the Postprandial Experience

“…Abdominal distension was related to a descent of the diaphragm with redistribution of normal abdominal contents. Using a biofeedback technique [ 30 ], patients learned to control the activity of the abdominal walls, and thereby prevented lettuce-induced distension [ 84 ]. Thus, abdominal distension in these patients is a somatic behavioral response, but why, in the first place, they acquired their belief and the mechanisms by which lettuce induces the abnormal response are not known.…”

“…Bloating is a subjective sensation of abdominal pressure/fullness, is a subjective sensation of abdominal distension, andinvolves an objective increase in girth [ 53 ]. While bloating is a visceral sensation related to hypersensitivity, abdominal distention is a behavioural somatic response, featuring diaphragmatic contraction and descent coupled with relaxation and protrusion of the anterior abdominal wall [ 28 , 30 , 84 ]. The relation between bloating and distention is not clear, but conceivably, the sensation of bloating triggers the somatic behavioural response leading to distention, and in turn, the somatic response worsens bloating sensation.…”

Abdominothoracic Postural Tone Influences the Sensations Induced by Meal Ingestion

“…It has been consistently shown that patients complaining of abdominal distension exhibit an objective increase in girth [ 2 ]. Abdominal distention is a behavioural somatic response featuring diaphragmatic contraction and descent coupled with relaxation and protrusion of the anterior abdominal wall [ 8 , 9 , 10 ].…”

Transplanting Microbes for Irritable Bowels or Irritated Microbes or Both?

“…This notion may be contestable, and bloating is not the same as flatulence, nor is it exclusively due to "a build-up of gas." 3,4 Regardless, the results of the trial will be welcome to many patients with bloating, which is notoriously difficult to manage. FMT was associated with symptom relief in about one-half of patients compared with about one-quarter of those receiving placebo (autologous stool).…”

“…FMT is also being investigated as a therapeutic treatment in several other human conditions, including inflammatory bowel disease, irritable bowel syndrome, liver and kidney disease, and obesity/metabolic syndrome. 4 Most FMT clinical trials use allogenic transplants, that is, fecal material obtained from a healthy donor and transplanted into a recipient either by enema, endoscopy, or in an encapsulated form. Conversely, autologous transplants, which are prepared from the patient's own fecal material, are frequently used as placebo therapy.…”