title: Probiotics for the prevention of allergy: A systematic review and meta-analysis of randomized controlled trials.
abstract: BACKGROUND
  Allergic diseases are considered a health burden because of their high and constantly increasing prevalence, high direct and indirect costs, and undesirable effects on quality of life. Probiotics have been suggested as an intervention to prevent allergic diseases.
  
  
  OBJECTIVE
  We sought to synthesize the evidence supporting use of probiotics for the prevention of allergies and inform World Allergy Organization guidelines on probiotic use.
  
  
  METHODS
  We performed a systematic review of randomized trials assessing the effects of any probiotic administered to pregnant women, breast-feeding mothers, and/or infants.
  
  
  RESULTS
  Of 2403 articles published until December 2014 identified in Cochrane Central Register of Controlled Trials, MEDLINE, and Embase, 29 studies fulfilled a priori specified inclusion criteria for the analyses. Probiotics reduced the risk of eczema when used by women during the last trimester of pregnancy (relative risk [RR], 0.71; 95% CI, 0.60-0.84), when used by breast-feeding mothers (RR, 0.57; 95% CI, 0.47-0.69), or when given to infants (RR, 0.80; 95% CI, 0.68-0.94). Evidence did not support an effect on other allergies, nutrition status, or incidence of adverse effects. The certainty in the evidence according to the Grading of Recommendation Assessment Development and Evaluation approach is low or very low because of the risk of bias, inconsistency and imprecision of results, and indirectness of available research.
  
  
  CONCLUSIONS
  Probiotics used by pregnant women or breast-feeding mothers and/or given to infants reduced the risk of eczema in infants; however, the certainty in the evidence is low. No effect was observed for the prevention of other allergic conditions.
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada; Tecnologico de Monterrey School of Medicine, Monterrey, Mexico.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Cuello-Garcia
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada; Department of Medicine, McMaster University, Hamilton, Ontario, Canada. Electronic address: brozekj@mcmaster.ca.
authors.forename: Jan L
authors.initials: JL
authors.lastname: Brożek
authors.affiliation: Pediatric Hospital Bambino Gesù, Vatican City.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Fiocchi
authors.affiliation: Department of Pediatrics, Nippon Medical School, Tokyo, Japan.
authors.forename: Ruby
authors.initials: R
authors.lastname: Pawankar
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada; University of Antioquia, School of Medicine, Medellin, Colombia.
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Yepes-Nuñez
authors.affiliation: Department of Child and Maternal Medicine, University of Milan Medical School at the Melloni Hospital, Milan, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Terracciano
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Ontario, Canada; Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Shreyas
authors.initials: S
authors.lastname: Gandhi
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Ontario, Canada; Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Arnav
authors.initials: A
authors.lastname: Agarwal
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada; Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Holger J
authors.initials: HJ
authors.lastname: Schünemann
mesh_terms: D000818:Animals; D001942:Breast Feeding; D019587:Dietary Supplements; D004485:Eczema / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D007231:Infant, Newborn; D008431:Maternal-Fetal Exchange; D064307:Microbiota / Q000276:immunology; D011247:Pregnancy; D019936:Probiotics / Q000008:administration & dosage* / Q000009:adverse effects; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D012306:Risk
keywords: Allergy; prevention; probiotics systematic reviews