Objective Markers Flatulence: Determination of Gas Production and Evacuation in Response to Dietary Manipulations

Background Some patients complain of excessive evacuation, which may become socially disabling (Azpiroz F & Malagelada J-R, 2005). However, the physiology and pathophysiology of flatulence remains poorly understood (Azpiroz F & Levitt DG, 2009).

Gas evacuated by anus originates by-and-large in the colon, where unabsorbed meal residues are fermented by colonic bacteria (Anderson et al., 1981;Levitt et al., 1987;Flourie et al., 1988). Indeed, it has been shown that some food components are incompletely absorbed in the small bowel and enter the colon (Wolever & Robb, 1992;Grimble, 1989;Steggerda FR, 1968;Wagner et al., 1977;Steggerda F.R. & Dimmick, 1966;Stone-Dorshow & Levitt, 1987;Wursch et al., 1989) and that other intraluminal substrates interfere with the absorption of nutrients (Boibin M et al., 1998;Hamberg et al., 1989;Brugge & Rosenfeld, 1987;Taylor et al., 1986;Layer et al., 1986). Hence, the volume of gas production and anal evacuation is determined by two main factors: the diet, particularly the amount of fermentable residues, and the individual composition of colonic microflora. Within subjects, gas output varies in relation to the diet (Steggerda FR, 1968;Kirk, 1949). However, there is a great interindividual variability, and gas evacuation in subjects maintained on a similar diet may differ substantially.

It has been shown that healthy subjects on a normal diet containing 200 g of beans evacuate 705 mL gas per 24 hours, whereas with a fiber the diet gas evacuation was 214 mL (Tomlin et al., 1991). In healthy subjects the frequency of gas evacuation is variable, usually around 10 evacuation per day (Furne & Levitt, 1996). Based on observations on a patient that who passed large amounts of flatus, a classification of foodstuffs depending on their gas producing capacity was elaborated (Sutalf LO & Levitt MD, 1979). Few studies on specific foodstuffs have been later added to complement this information (Wolever & Robb, 1992;Wagner et al., 1977;Hickey C et al., 1972). However, there no systematic investigation on the range of gas evacuation in healthy subjects and in subjects complaining of flatulence under basal conditions and in response to a high-flatulogenic diet.

Procedures Recruitment questionnaire A questionnaire will be used to evaluate gas evacuation, bowel habit and functional gut symptoms.

Daily measurement of the number of anal gas evacuations and symptoms The number of gas evacuations per anus will be measured using an event marker during daytime. At the end of the day the following parameters will be recorded on a questionnaire: discomfort related to flatulence and evaluation of abdominal discomfort/pain (using 0-10 analogue scales); the number of bowel movements and form (using the Bristol scale; (Heaton & O'Donnell, 1994) and gastrointestinal well-being (satisfaction/dissatisfaction using a 10 point scale graded from +5 to -5).