title: Persistence of Lactobacillus reuteri DSM17938 in the human intestinal tract: response to consecutive and alternate-day supplementation.
abstract: BACKGROUND
  Probiotics may enhance gastrointestinal health and immune function. The efficacy of different probiotic dosing strategies on colonization and persistence of probiotics is undefined.
  
  
  OBJECTIVE
  The authors assessed colonization and persistence of Lactobacillus reuteri (L. reuteri) DSM17938 (BioGaia AB, Stockholm, Sweden) after daily or alternate-day dosing.
  
  
  METHODS
  Volunteers ate pudding with L. reuteri (10(9) CFU) daily (n = 9) or on alternate days (n = 9) over 7 days. Fecal samples were collected on dosing days (D1-7) and after dosing ended (D13-15 and D20-22) and were analyzed for the presence of L. reuteri. Results are reported in 3-day increments (D2-4, D5-7, D13-15, and D20-22).
  
  
  RESULTS
  L. reuteri count rose in response to daily supplementation ([mean ± SD] D2-4: 4 × 10⁴ ± 2 × 10⁴ CFU, p < 0.01; D5-7: 10 × 10⁴ ± 9 × 10⁴ CFU, p < 0.01) and alternate-day supplementation (D2-4: 21 × 10⁴ ± 20 × 10⁴ CFU, p < 0.01; D5-7: 11 × 10⁴ ± 15 × 10⁴ CFU, p = 0.06) and fell in both groups 1 week after dosing ended (p < 0.01). Total volunteers with detectable L. reuteri 1 and 2 weeks after dosing ended was similar in response to daily feeding (4/9 and 2/9, respectively) and alternate-day feeding (3/9 and 2/9, respectively). L. reuteri count was higher D2-4 in response to alternate-day vs daily feeding (p < 0.05) but similar thereafter.
  
  
  CONCLUSIONS
  Alternate-day probiotic intake achieves equivalent colonization to daily intake, but colonization declines rapidly once dosing stops. It is possible that, initially, responsiveness to probiotics may differ between individuals, but those differences do not persist with longer consumption.
authors.affiliation: U.S. Army Research Institute of Environmental Medicine, Military Nutrition Division, Kansas Street, Building 42, Natick, MA 01760. tracey.j.smith@us.army.mil
authors.forename: Tracey J
authors.initials: TJ
authors.lastname: Smith
authors.forename: Danielle
authors.initials: D
authors.lastname: Anderson
authors.forename: Lee M
authors.initials: LM
authors.lastname: Margolis
authors.forename: Anthony
authors.initials: A
authors.lastname: Sikes
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Young
mesh_terms: D000293:Adolescent; D000328:Adult; D019587:Dietary Supplements; D005243:Feces / Q000382:microbiology; D005260:Female; D041981:Gastrointestinal Tract / Q000276:immunology / Q000382:microbiology*; D006801:Humans; D052200:Limosilactobacillus reuteri / Q000254:growth & development* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D019936:Probiotics / Q000008:administration & dosage*; D011795:Surveys and Questionnaires; D055815:Young Adult