title: Modeling 13C breath curves to determine site and extent of starch digestion and fermentation in infants.
abstract: BACKGROUND
  The colon salvages energy from starch, especially when the capacity of the small intestine to digest it is limited. The aim of this study was to determine the site and relative extent of starch digestion and fermentation in infants.
  
  
  METHODS
  Thirteen infants (10 male and 3 female infants), median age 11.8 months (range, 7.6-22.7 months), were fed a starchy breakfast containing 13C-labeled wheat flour after an overnight fast. Duplicate breath samples were obtained before breakfast and every 30 minutes for 12 hours. Breath 13CO2 enrichment was measured using isotope ratio mass spectrometry, and results were expressed as percentage dose recovered (PDR) for each 30 minutes. The PDR data were analyzed and mathematically modeled assuming either a constant estimate of CO2 production rate or adjusted for physical activity.
  
  
  RESULTS
  Mean +/- SD cumulative 13C PDR (cPDR) at 12 hours was 21.3% +/- 8.4% for unadjusted data and 26.5% +/- 11.6% for adjusted data. A composite model of two curves fit significantly better than a single curve. Modeling allowed estimation of cPDRs of small intestine (17.5% +/- 6.5% and 22.7% +/- 9.3% for unadjusted and adjusted data, respectively) and colon (4.6% +/- 2.9% and 6.3% +/- 5.4%).
  
  
  CONCLUSIONS
  Modeling of 13CO2 enrichment curves after ingestion of 13C-enriched wheat flour is an attractive means to estimate the contribution of the upper and lower gut to starch digestion and fermentation.
authors.affiliation: Department of Child Health, University of Glasgow, Scotland.
authors.forename: Martin T
authors.initials: MT
authors.lastname: Christian
authors.forename: Sergio
authors.initials: S
authors.lastname: Amarri
authors.forename: Fabio
authors.initials: F
authors.lastname: Franchini
authors.forename: Tom
authors.initials: T
authors.lastname: Preston
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Morrison
authors.forename: Brian
authors.initials: B
authors.lastname: Dodson
authors.forename: Christine A
authors.initials: CA
authors.lastname: Edwards
authors.forename: Lawrence T
authors.initials: LT
authors.lastname: Weaver
mesh_terms: D001944:Breath Tests; D002245:Carbon Dioxide / Q000032:analysis*; D002247:Carbon Isotopes; D003106:Colon / Q000378:metabolism*; D004063:Digestion; D005260:Female; D005285:Fermentation; D006801:Humans; D007223:Infant; D007700:Kinetics; D008297:Male; D013058:Mass Spectrometry; D008954:Models, Biological; D013213:Starch / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D002245:Carbon Dioxide; D013213:Starch