A randomized clinical trial measuring the influence of kefir on antibiotic-associated diarrhea: the measuring the influence of Kefir (MILK) Study

Arch Pediatr Adolesc Med. 2009 Aug;163(8):750-4. doi: 10.1001/archpediatrics.2009.119.


Objective: To examine the role of commercially available kefir, a fermented milk similar to yogurt but containing different fermentation microbes, in preventing antibiotic-associated diarrhea (AAD). Probiotics have shown some promise in preventing AAD.

Design: A double-blinded randomized placebo-controlled allocation concealment clinical trial.

Setting: Primary care patients in the Washington, DC, metropolitan area.

Participants: A total of 125 children aged 1 to 5 years presenting to primary care physicians. Intervention Kefir drink or heat-killed matching placebo. Main Outcome Measure The primary outcome was the incidence of diarrhea during the 14-day follow-up period in children receiving antibiotics.

Results: There were no differences in the rates of diarrhea per group, with 18% in the active group and 21.9% in the placebo group (relative risk, 0.82; 95% confidence interval, 0.54-1.43). Additionally, there were no differences in any secondary outcomes among the groups. However, there were some interesting interactions among initial health at enrollment, age of participants, and sex that require further study.

Conclusions: In our trial, kefir did not prevent AAD. Further independent research on the potential of kefir needs to be conducted.

Trial registration: ClinicalTrials.gov NCT00481507.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Disease
  • Anti-Bacterial Agents / adverse effects*
  • Child, Preschool
  • Cultured Milk Products*
  • Diarrhea / chemically induced*
  • Diarrhea / diet therapy*
  • Double-Blind Method
  • Female
  • Humans
  • Infant
  • Logistic Models
  • Male
  • Placebos
  • Probiotics / therapeutic use*
  • Treatment Outcome


  • Anti-Bacterial Agents
  • Placebos

Associated data

  • ClinicalTrials.gov/NCT00481507