Decreased duration of acute upper respiratory tract infections with daily intake of fermented milk: a multicenter, double-blinded, randomized comparative study in users of day care facilities for the elderly population

Am J Infect Control. 2013 Dec;41(12):1231-5. doi: 10.1016/j.ajic.2013.04.005. Epub 2013 Jul 23.


Background: There is insufficient evidence of preventive effect of probiotics on upper respiratory tract infections (URTIs) in an elderly population.

Methods: We conducted a multicenter, double-blinded, randomized, placebo-controlled parallel group study. Elderly persons had participated who used day care at 4 facilities in Tokyo. We used fermented milks containing Lactobacillus casei strain Shirota (LcS) and placebo drinks as test drinks.

Results: A total of 154 subjects was analyzed. The number of persons diagnosed with an acute URTIs was almost identical in both groups (LcS: 31, placebo: 32), whereas the number of acute URTIs events (LcS: 68, placebo: 51) and the symptom score (LcS: 425, placebo: 396) were both higher in the LcS group. Permutation tests performed using the total number of acute URTIs infection events/total days of observation and the total symptom score/total days of observation found no statistically significant difference respectively (P values of .89 and .64, respectively). Comparing the mean duration of infection per infection event found a shorter mean duration in the LcS group (LcS: 3.71 days, placebo: 5.40 days), and the difference was statistically significant.

Conclusion: The results suggest that fermented milk containing LcS probably reduces the duration of acute URTIs.

Keywords: Compromised host; Geriatric health services; Lactobacillus casei strain Shirota; Probiotics.

Publication types

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

MeSH terms

  • Aged
  • Aged, 80 and over
  • Dairy Products*
  • Day Care, Medical
  • Diet / methods*
  • Double-Blind Method
  • Female
  • Health Services for the Aged*
  • Humans
  • Male
  • Placebos / administration & dosage
  • Respiratory Tract Infections / pathology*
  • Respiratory Tract Infections / prevention & control*
  • Time Factors
  • Tokyo


  • Placebos