title: Probiotics for preventing acute upper respiratory tract infections.
abstract: BACKGROUND
  Probiotics may improve a person's health by regulating their immune function. Some studies show that probiotic strains can prevent respiratory infections. However, no evidence of the benefits of probiotics for acute upper respiratory tract infections (URTIs) and related potential adverse effects has been published.
  
  
  OBJECTIVE
  To assess the effectiveness and safety of probiotics for preventing acute URTIs.
  
  
  METHODS
  We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 2), which includes the Cochrane Acute Respiratory Infections Group's Specialised Register, MEDLINE (Ovid) (1950 to May week 1, 2011), EMBASE (1974 to May 2011), Web of Science which includes Science Citation Index (from 1900 to May 2011) and Conference Proceedings Citation Index (from 1991 to May 2011), the Chinese Biomedical Literature Database, which includes the China Biological Medicine Database (from 1978 to May 2011), the Chinese Medicine Popular Science Literature Database (from 2000 to May 2011) and the Masters Degree Dissertation of Beijing Union Medical College Database (from 1981 to May 2011).
  
  
  METHODS
  Randomised controlled trials (RCTs) comparing probiotics with placebo to prevent acute URTIs.
  
  
  METHODS
  Two review authors independently assessed eligibility, quality of trials and extracted data.
  
  
  RESULTS
  We included 14 RCTs, although we could only extract available data to meta-analyse in 10 trials which involved 3451 participants. We found that probiotics were better than placebo when measuring the number of participants experiencing episodes of acute URTI: at least one episode: odds ratio (OR) 0.58; 95% confidence interval (CI) 0.36 to 0.92; at least three episodes: OR 0.53; 95% CI 0.36 to 0.80; rate ratio of episodes of acute URTI: rate ratio 0.88; 95% CI 0.81 to 0.96; and reduced antibiotic prescription rates for acute URTIs: OR 0.67; 95% CI 0.45 to 0.98. Probiotics and placebo were similar when measuring the mean duration (MD) of an episode of acute URTI: MD -0.29; 95% CI -3.71 to 3.13 and adverse events: OR 0.92; 95% CI 0.37 to 2.28. Side effects of probiotics were minor and gastrointestinal symptoms were the most common. We found that some subgroups had a high level of heterogeneity when conducting pooled analyses.
  
  
  CONCLUSIONS
  Probiotics were better than placebo in reducing the number of participants experiencing episodes of acute URTIs, the rate ratio of episodes of acute URTI and reducing antibiotic use. This indicates that probiotics may be more beneficial than placebo for preventing acute URTIs. However, the results have some limitations and there were no data for older people.
authors: Department of Geriatrics, West China Hospital, Sichuan University, No. 37, Guo Xue Xiang, Chengdu, Sichuan, China, 610041.
authors: Qiukui
authors: Q
authors: Hao
authors: Zhenchan
authors: Z
authors: Lu
authors: Bi Rong
authors: BR
authors: Dong
authors: Chang Quan
authors: CQ
authors: Huang
authors: Taixiang
authors: T
authors: Wu
mesh_terms: D000208:Acute Disease; D006801:Humans; D019936:Probiotics / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic; D012141:Respiratory Tract Infections / Q000517:prevention & control*