Gas production by feces of infants

Background: Intestinal gas is thought to be the cause abdominal discomfort in infants. Little is known about the type and amount of gas produced by the infant's colonic microflora and whether diet influences gas formation. Methods: Fresh stool specimens were collected from 10 breast-fed infants, 5 infants fed a soy-based formula, and 3 infants fed a milk-based formula at approximately 1, 2, and 3 months of age. Feces were incubated anaerobically for 4 hours at 37°C followed by quantitation of hydrogen (H₂), methane (CH₄), carbon dioxide (CO₂), hydrogen sulfide (H₂S), methanethiol (CH₃SH), and dimethyl sulfide (CH₃SCH₃) in the headspace. Results: H₂ was produced in greater amounts by breast-fed infants than by infants in either formula group, presumably the consequence of incomplete absorption of breast milk oligosaccharides. CH₄ was produced in greater amounts by infants fed soy formula than by infants on other diets. CO₂ was produced in similar amounts by infants in all feeding groups. Production of CH₃SH was conspicuously low by feces of breast-fed infants and production of H₂S was high by soy-formula-fed infants. CH₃SCH₃ was not detected. Only modest changes with age were observed and there was no relation between gas production and stool consistency, although stools were more likely to be malodorous when concentrations of H₂S and/or CH₃SH were high. Conclusions: Gas release by infant feces is strongly influenced by an infant's diet. Of particular interest are differences in production of the highly toxic sulfur gases, H₂S and CH₃SH, because of the role that these gases may play in certain intestinal disorders of infants.