title: A curve fitting approach to estimate the extent of fermentation of indigestible carbohydrates.
abstract: BACKGROUND
  Information about the extent of carbohydrate digestion and fermentation is critical to our ability to explore the metabolic effects of carbohydrate fermentation in vivo. We used cooked (13)C-labelled barley kernels, which are rich in indigestible carbohydrates, to develop a method which makes it possible to distinguish between and to assess carbohydrate digestion and fermentation.
  
  
  METHODS
  Seventeen volunteers ingested 86 g (dry weight) of cooked naturally (13)C enriched barley kernels after an overnight fast. (13)CO(2) and H(2) in breath samples were measured every half hour for 12 h. The data of (13)CO(2) in breath before the start of the fermentation were used to fit the curve representing the digestion phase. The difference between the area under curve (AUC) of the fitted digestion curve and the AUC of the observed curve was regarded to represent the fermentation part. Different approaches were applied to determine the proportion of the (13)C-dose available for digestion and fermentation.
  
  
  RESULTS
  Four hours after intake of barley, H(2)-excretion in breath started to rise. Within 12 h, 24-48% of the (13)C-dose was recovered as (13)CO(2), of which 18-19% was derived from colonic fermentation and the rest from digestion. By extrapolating the curve to baseline, it was estimated that eventually 24-25% of the total available (13)C in barley would be derived from colon fermentation.
  
  
  CONCLUSIONS
  Curve fitting, using (13)CO(2)- and H(2)-breath data, is a feasible and non-invasive method to assess carbohydrate digestion and fermentation after consumption of (13)C enriched starchy food.
authors.affiliation: Centre for Medical Biomics, University Medical Centre Groningen, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.forename: D
authors.initials: D
authors.lastname: Weening
authors.forename: E
authors.initials: E
authors.lastname: Jonkers
authors.forename: T
authors.initials: T
authors.lastname: Boer
authors.forename: F
authors.initials: F
authors.lastname: Stellaard
authors.forename: A C
authors.initials: AC
authors.lastname: Small
authors.forename: T
authors.initials: T
authors.lastname: Preston
authors.forename: R J
authors.initials: RJ
authors.lastname: Vonk
authors.forename: M G
authors.initials: MG
authors.lastname: Priebe
mesh_terms: D000328:Adult; D019540:Area Under Curve; D001944:Breath Tests; D002245:Carbon Dioxide / Q000032:analysis*; D002247:Carbon Isotopes; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000378:metabolism*; D004063:Digestion; D005260:Female; D005285:Fermentation; D001467:Hordeum; D006801:Humans; D006859:Hydrogen / Q000032:analysis*; D008297:Male; D013213:Starch / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D004040:Dietary Carbohydrates; D002245:Carbon Dioxide; D006859:Hydrogen; D013213:Starch