title: Efficacy of daily intake of Lactobacillus casei Shirota on respiratory symptoms and influenza vaccination immune response: a randomized, double-blind, placebo-controlled trial in healthy elderly nursing home residents.
abstract: BACKGROUND
  Age is associated with immune dysregulation, which results in an increased infection rate and reduced effectiveness of vaccination.
  
  
  OBJECTIVE
  We assessed whether an intervention with Lactobacillus casei Shirota (LcS) in elderly nursing home residents reduced their susceptibility to respiratory symptoms and improved their immune response to influenza vaccination.
  
  
  METHODS
  Between October 2007 and April 2008, a randomized, double-blind, placebo-controlled trial was conducted in 737 healthy people aged ≥ 65 y in 53 nursing homes in Antwerp, Belgium. Volunteers were randomly assigned to receive a probiotic (n = 375; 2 bottles of fermented milk that contained ≥ 6.5 × 10(9) live LcS/bottle) or a placebo (n = 362; similar drink with no bacteria) for 176 d. After 21 d, all subjects received an influenza vaccination. Primary outcome parameters were the number of days with respiratory symptoms, the probability of respiratory symptoms, and antiinfluenza antibody titer by hemagglutination inhibition after vaccination.
  
  
  RESULTS
  Univariate and multivariate modeling showed no effect of the probiotic on clinical outcome parameters. Generalized linear mixed modeling showed no effect of the probiotic itself on the probability of respiratory symptoms [OR of probiotic: 0.8715; 95% CI: 0.6168, 1.2887). No significant difference regarding the influenza-vaccination immune response was shown.
  
  
  CONCLUSIONS
  The results of this study show that daily consumption of a fermented milk drink that contains LcS has no statistically or clinically significant effect on the protection against respiratory symptoms. This trial was registered at clinicaltrials.gov as NCT00849277.
authors.affiliation: Department of Primary and Interdisciplinary Care, University of Antwerp, Antwerp, Belgium. karolien.vanpuyenbroeck@ua.ac.be
authors.forename: Karolien
authors.initials: K
authors.lastname: Van Puyenbroeck
authors.forename: Niel
authors.initials: N
authors.lastname: Hens
authors.forename: Samuel
authors.initials: S
authors.lastname: Coenen
authors.forename: Barbara
authors.initials: B
authors.lastname: Michiels
authors.forename: Caroline
authors.initials: C
authors.lastname: Beunckens
authors.forename: Geert
authors.initials: G
authors.lastname: Molenberghs
authors.forename: Paul
authors.initials: P
authors.lastname: Van Royen
authors.forename: Veronique
authors.initials: V
authors.lastname: Verhoeven
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000906:Antibodies / Q000097:blood; D001530:Belgium; D004311:Double-Blind Method; D005260:Female; D005285:Fermentation; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007252:Influenza Vaccines / Q000276:immunology*; D007780:Lacticaseibacillus casei; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008892:Milk / Q000382:microbiology*; D015999:Multivariate Analysis; D009735:Nursing Homes; D019936:Probiotics / Q000008:administration & dosage*; D014611:Vaccination
chemical_list: D000906:Antibodies; D007252:Influenza Vaccines