Baseline microbiota activity and initial bifidobacteria counts influence responses to prebiotic dosing in healthy subjects

Aliment Pharmacol Ther. 2008 Mar 15;27(6):504-13. doi: 10.1111/j.1365-2036.2007.03588.x. Epub 2007 Dec 10.


Background: Dietary intervention with prebiotics can cause changes in the colonic microbiota and their metabolic activities.

Aim: 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).

Conclusion: The response to prebiotic dosing, as indicated by the fate of NH(3), p-cresol and bifidobacteria, is determined by the initial colonic conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Bifidobacterium / drug effects
  • Bifidobacterium / growth & development*
  • Colon / microbiology*
  • Colony Count, Microbial
  • Dietary Carbohydrates / administration & dosage
  • Dietary Carbohydrates / metabolism
  • Dietary Carbohydrates / pharmacology*
  • Feces / microbiology
  • Female
  • Gastrointestinal Transit
  • Humans
  • Male
  • Probiotics / administration & dosage*


  • Dietary Carbohydrates