Table 2

Summary of selected systematic reviews and meta-analyses reporting on probiotics and respiratory infections

AuthorsPopulationIncluded trialsProbioticOutcomeEffect
Vouloumanou et al 207 Children and adults14 RCTs (3580 participants)Any (mainly lactobacilli and bifidobacteria)RTI4/10 RCTs reported probiotics reduced incidence of RTI
5/6 RCTs reported probiotics reduced severity of symptoms of RTI
3/9 RCTS reported probiotics shortened duration of RTI
Liu et al 208 Critically ill adults12 RCTs (1546 patients)AnyNosocomial pneumoniaOR of nosocomial pneumonia with probiotics 0.75 (95% CI 0.57 to 0.97)
No effect of probiotics on in hospital mortality, intensive care unit mortality, duration of hospital stay, duration of intensive care unit stay
Liu et al 209 Children4 RCTs (1805 children) Lactobacillus rhamnosus GG RTIRR of URTI with probiotics 0.62 (95% CI 0.50 to 0.78)
RR for antibiotic treatment for URTI with probiotics 0.80 (95% CI 0.71 to 0.91)
No effect of probiotics on LRTI or overall respiratory infections
King et al 210 Children and adults20 RCTs (>4141 participants)AnyRTISMD days of illness per person with probiotics −0.31 (95% CI −0.41 to −0.11);
WMD days of illness with probiotics −0.77 (95% CI −1.50 to −0.04);
SMD days of absence with probiotics −0.17 (95% CI −0.31 to −0.03)
Hao et al 211 Children and adults13 RCTs; 12 RCTS in meta-analysis (3750 participants)AnyURTIOR of one URTI with probiotics 0.53 (95% CI 0.37 to 0.76)
OR of at least three URTIs with probiotics 0.53 (95% CI 0.36 to 0.80)
Mean duration of episode of URTI with probiotics −1.89 days (95% CI −2.03 to −1.75)
OR for antibiotic prescription for URTI with probiotics 0.65 (95% CI 0.45 to 0.94)
Ozen et al 212 Children14 RCTsAny (mainly lactobacilli and bifidobacteria)URTIAt least one beneficial effect of probiotics was observed in most of the RCTs
Araujo et al 213 Children11 RCTs (2417 children)AnyRTISeveral RCTs reports fewer new episodes, decreased duration of episodes and less severe symptoms
Wang et al 214 Children23 RCTs (6269 children)AnyRTIRR of one RTI with probiotics 0.80 (95% CI 0.82 to 0.96);
Days of RTI per child with probiotics −0.16 (95% CI −0.29 to 0.02)
Days absent with probiotics −0.94 (95% CI −1.72 to −0.15)
Laursen and Hojsak215 Children15 RCTs; 12 RCTs in meta-analysis (4527 children)AnyRTI L. rhamnosus GG reduced duration of RTI −0.78 days (95% CI −1.46 to −0.090)
Meta-analysis for other probiotics is not possible
  • LRTI, lower respiratory tract infection; RCT, randomised controlled trial; RR, relative risk; RTI, respiratory tract infection; SMD, standardised mean difference; URTI, upper respiratory tract infection; WMD, weighted mean difference.