title: The effect of probiotics on functional constipation in adults: a systematic review and meta-analysis of randomized controlled trials.
abstract: BACKGROUND
  Functional constipation is a prevalent, burdensome gastrointestinal disorder whose treatment remains challenging. Probiotics have been increasingly investigated in its management.
  
  
  OBJECTIVE
  The aim was to investigate the effect of probiotics on gut transit time, stool output, and constipation symptoms in adults with functional constipation via a systematic review and meta-analysis of randomized controlled trials (RCTs).
  
  
  METHODS
  Studies were identified by searching 4 electronic databases, back-searching reference lists, contacting authors, and hand-searching abstracts. RCTs that reported administration of probiotics in adults with functional constipation were included. Two reviewers independently performed the screening, data extraction, and bias assessment. Outcome data were synthesized by using weighted mean differences (WMDs) or standardized mean differences (SMDs) with the use of a random-effects model.
  
  
  RESULTS
  A total of 660 records were identified of which 14 were eligible (1182 patients). Overall, probiotics significantly reduced whole gut transit time by 12.4 h (95% CI: -22.3, -2.5 h) and increased stool frequency by 1.3 bowel movements/wk (95% CI: 0.7, 1.9 bowel movements/wk), and this was significant for Bifidobacterium lactis (WMD: 1.5 bowel movements/wk; 95% CI: 0.7, 2.3 bowel movements/wk) but not for Lactobacillus casei Shirota (WMD: -0.2 bowel movements/wk; 95% CI: -0.8, 0.9 bowel movements/wk). Probiotics improved stool consistency (SMD: +0.55; 95% CI: 0.27, 0.82), and this was significant for B. lactis (SMD: +0.46; 95% CI: 0.08, 0.85) but not for L. casei Shirota (SMD: +0.26; 95% CI: -0.30, 0.82). No serious adverse events were reported. Attrition and reporting bias were high, whereas selection bias was unclear due to inadequate reporting.
  
  
  CONCLUSIONS
  Probiotics may improve whole gut transit time, stool frequency, and stool consistency, with subgroup analysis indicating beneficial effects of B. lactis in particular. However, caution is needed with the interpretation of these data due to their high heterogeneity and risk of bias. Adequately powered RCTs are required to better determine the species or strains, doses, and duration of use of probiotics that are most efficacious.
authors.affiliation: From the Diabetes and Nutritional Sciences Division, School of Medicine, King's College London, London, United Kingdom (ED, SC, and KW); the Centre for Digestive Diseases, Neurogastroenterology Group and GI Physiology Unit, Queen Mary University of London, London, United Kingdom (ED, SC, and SMS); and the Division of Medicine, Centre for Gastroenterology and Clinical Nutrition, University College London, London, United Kingdom (KCF).
authors.forename: Eirini
authors.initials: E
authors.lastname: Dimidi
authors.affiliation: From the Diabetes and Nutritional Sciences Division, School of Medicine, King's College London, London, United Kingdom (ED, SC, and KW); the Centre for Digestive Diseases, Neurogastroenterology Group and GI Physiology Unit, Queen Mary University of London, London, United Kingdom (ED, SC, and SMS); and the Division of Medicine, Centre for Gastroenterology and Clinical Nutrition, University College London, London, United Kingdom (KCF).
authors.forename: Stephanos
authors.initials: S
authors.lastname: Christodoulides
authors.affiliation: From the Diabetes and Nutritional Sciences Division, School of Medicine, King's College London, London, United Kingdom (ED, SC, and KW); the Centre for Digestive Diseases, Neurogastroenterology Group and GI Physiology Unit, Queen Mary University of London, London, United Kingdom (ED, SC, and SMS); and the Division of Medicine, Centre for Gastroenterology and Clinical Nutrition, University College London, London, United Kingdom (KCF).
authors.forename: Konstantinos C
authors.initials: KC
authors.lastname: Fragkos
authors.affiliation: From the Diabetes and Nutritional Sciences Division, School of Medicine, King's College London, London, United Kingdom (ED, SC, and KW); the Centre for Digestive Diseases, Neurogastroenterology Group and GI Physiology Unit, Queen Mary University of London, London, United Kingdom (ED, SC, and SMS); and the Division of Medicine, Centre for Gastroenterology and Clinical Nutrition, University College London, London, United Kingdom (KCF).
authors.forename: S Mark
authors.initials: SM
authors.lastname: Scott
authors.affiliation: From the Diabetes and Nutritional Sciences Division, School of Medicine, King's College London, London, United Kingdom (ED, SC, and KW); the Centre for Digestive Diseases, Neurogastroenterology Group and GI Physiology Unit, Queen Mary University of London, London, United Kingdom (ED, SC, and SMS); and the Division of Medicine, Centre for Gastroenterology and Clinical Nutrition, University College London, London, United Kingdom (KCF).
authors.forename: Kevin
authors.initials: K
authors.lastname: Whelan
mesh_terms: D003248:Constipation / Q000628:therapy*; D003672:Defecation / Q000502:physiology; D006801:Humans; D019936:Probiotics / Q000008:administration & dosage*; D016032:Randomized Controlled Trials as Topic