title: Methane and hydrogen exhalation in normal children and in lactose malabsorption.
abstract: Methane (CH4) and hydrogen (H2) are gases produced in the colon by the breakdown of carbohydrates, due to the action of anaerobic methanogenic bacteria. No papers have been published in pediatrics concerning these gases production and exhalation. Understanding of the pattern of H2, CH4, carbon dioxide (CO2), butyrates, indolellipsis,etc., production and exhalation, which may differ in gastrointestinal diseases, may be helpful as far as the diagnosis and treatment of some gastrointestinal conditions is concerned. Exhalation of H2, CH4 and CO2 by breath air was studied in basal conditions in 338 normal infants and in 27 lactose malabsorbers. Moreover, stools collected and stored for 10-12 h in anaerobic and aerobic conditions were incubated in anaerobiosis at 38 degrees C. After a 4-h incubation period, H2, CH4 and CO2 were determined.
  
  
  RESULTS
  Methane production is independent of hydrogen production; the number of children producing CH4 increases from 0% at 12 months of age to 44% at the age of 9 years. In lactose malabsorption, we found 26 children producing increased quantities of H2 and no methane, and only one producing methane but no hydrogen, which proves that methanogenic bacteria are independent of H2-producing bacteria, and that CH4 determination is compulsory in the study of lactose malabsorption. The incubation of stools in an anaerobic milieu at 38 degrees C for 4 h, in an attempt to imitate the human colon, showed a great production of methane and less of H2 in the stools collected and stored in anaerobic conditions. The same incubation method was applied to the stools collected and stored in aerobic conditions: production of H2 and CH4 was much lower than in the collected and stored anaerobic group. The appearance of CH4 in the stools of the aerobic group proves that methanogenic bacteria are, to a small degree, resistant to oxygen.
  
  
  CONCLUSIONS
  The study of gas exhalation in pediatrics merits more study by researchers, with a view to defining a special pattern of gas production in pathological conditions. The anaerobic stool incubation method is a good model for studying gas production under the effect of different diets and the gas production pattern in gastrointestinal diseases.
authors.affiliation: Unidad de Gastroenterología Infantil y Nutrición, Hospital Materno-Infantil Vall d'Hebron, Paseo de la Vall d'Hebron, s/n, 08035, Barcelona, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Tormo
authors.forename: A
authors.initials: A
authors.lastname: Bertaccini
authors.forename: M
authors.initials: M
authors.lastname: Conde
authors.forename: D
authors.initials: D
authors.lastname: Infante
authors.forename: I
authors.initials: I
authors.lastname: Cura
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D001419:Bacteria / Q000378:metabolism; D001944:Breath Tests; D002648:Child; D002675:Child, Preschool; D005243:Feces / Q000737:chemistry / Q000382:microbiology; D006801:Humans; D006859:Hydrogen / Q000032:analysis*; D007223:Infant; D007231:Infant, Newborn; D007787:Lactose Intolerance / Q000378:metabolism*; D008697:Methane / Q000032:analysis*; D012016:Reference Values
chemical_list: D006859:Hydrogen; D008697:Methane