title: Baseline microbiota activity and initial bifidobacteria counts influence responses to prebiotic dosing in healthy subjects.
abstract: BACKGROUND
  Dietary intervention with prebiotics can cause changes in the colonic microbiota and their metabolic activities.
  
  
  OBJECTIVE
  To investigate whether the response to prebiotic dosing is influenced by the baseline metabolic activity of the colonic flora and bifidobacteria counts.
  
  
  METHODS
  The 4-week effect of lactulose (10 g bid.; n = 29) and oligofructose-enriched inulin (10 g bid.; n = 19) was evaluated in healthy human volunteers. Lactose-[(15)N, (15)N]-ureide was used to study the colonic NH(3)-metabolism. Urine (48 h) and faeces (72 h) were collected and analysed for p-cresol and (15)N-content by gas chromatography-mass spectrometry and isotope ratio mass spectrometer, respectively. Faecal bifidobacteria were quantified by real-time polymerase chain reaction.
  
  
  RESULTS
  After the 4-week prebiotic administration period, the urinary excretion of p-cresol and (15)N was significantly decreased in both groups (P < 0.05) corresponding to a significantly higher faecal excretion of (15)N (P < 0.05). The decrease in urinary (15)N and p-cresol excretion significantly correlated with baseline (15)N and p-cresol levels (P < 0.05), indicating that subjects with higher baseline levels showed a higher response to prebiotic dosing. Furthermore, a significant correlation was seen between baseline bifidobacteria counts and the effect of prebiotic intake (P < 0.05).
  
  
  CONCLUSIONS
  The response to prebiotic dosing, as indicated by the fate of NH(3), p-cresol and bifidobacteria, is determined by the initial colonic conditions.
authors: Department of Gastrointestinal Research, University Hospital Gasthuisberg, K.U. Leuven, Leuven, Belgium.
authors: V
authors: V
authors: de Preter
authors: T
authors: T
authors: Vanhoutte
authors: G
authors: G
authors: Huys
authors: J
authors: J
authors: Swings
authors: P
authors: P
authors: Rutgeerts
authors: K
authors: K
authors: Verbeke
mesh_terms: D000328:Adult; D001644:Bifidobacterium / Q000187:drug effects / Q000254:growth & development*; D003106:Colon / Q000382:microbiology*; D015169:Colony Count, Microbial; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D005243:Feces / Q000382:microbiology; D005260:Female; D005772:Gastrointestinal Transit; D006801:Humans; D008297:Male; D019936:Probiotics / Q000008:administration & dosage*
chemical_list: D004040:Dietary Carbohydrates