Persistence of Lactobacillus reuteriDSM17938 in the Human Intestinal Tract: Response to Consecutive and Alternate-Day Supplementation

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(109CFU) 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. reutericount rose in response to daily supplementation ([mean ± SD] D2–4: 4 × 104± 2 × 104CFU, p< 0.01; D5–7: 10 × 104± 9 × 104CFU, p< 0.01) and alternate-day supplementation (D2–4: 21 × 104± 20 × 104CFU, p< 0.01; D5–7: 11 × 104± 15 × 104CFU, p= 0.06) and fell in both groups 1 week after dosing ended (p< 0.01). Total volunteers with detectable L. reuteri1 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. reutericount 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.