title: Effect of probiotic species on irritable bowel syndrome symptoms: A bring up to date meta-analysis.
abstract: OBJECTIVE
  immune system alteration in irritable bowel syndrome (IBS) patients may be modulated by probiotics. We assessed the efficacy of some probiotic species in alleviating characteristic IBS symptoms.
  
  
  METHODS
  a meta-analysis of all identified randomized controlled trials comparing probiotics with placebo in treating IBS symptoms was performed with continuous data summarized using standardized mean differences (SMDs) with 95% confidence intervals (95% CIs), where appropriate. The random-effects model was employed in cases of heterogeneity; otherwise, fixed-effects models were used.
  
  
  RESULTS
  meta-analysis was performed with 10 of 24 studies identified as suitable for inclusion. Probiotics improved pain scores if they contained Bifidobacterium breve (SMD, - 0.34; 95% CI, - 0.66; -0.02), Bifidobacterium longum (SMD, -0.48; 95% CI, - 0.91; -0.06), or Lactobacillus acidophilus (SMD, -0.31; 95% CI, -0.61; -0.01) species. Distension scores were improved by probiotics containing B. breve (SMD, -0.45; 95% CI, -0.77; -0.13), Bifidobacterium infantis, Lactobacillus casei, or Lactobacillus plantarum (SMD, -0.53; 95% CI, -1.00; -0.06) species. All probiotic species tested improved flatulence: B. breve (SMD, -0.42; 95% CI, -0.75;- 0.10), B. infantis, L. casei, L. plantarum (SMD, -0.60; 95% CI, -1.07; -0.13), B. longum, L. acidophilus, Lactobacillus bulgaricus, and Streptococcus salivarius ssp. thermophilus (SMD, -0.61; 95% CI, -1.01; -0.21). There was not a clear positive effect of probiotics concerning the quality of life.
  
  
  CONCLUSIONS
  some probiotics are an effective therapeutic option for IBS patients, and the effects on each IBS symptom are likely species-specific. Future studies must focus on the role of probiotics in modulating intestinal microbiota and the immune system while considering individual patient symptom profiles.
authors.forename: María
authors.initials: M
authors.lastname: Ortiz-Lucas
authors.forename: Aurelio
authors.initials: A
authors.lastname: Tobías
authors.forename: Pablo
authors.initials: P
authors.lastname: Saz
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Sebastián
mesh_terms: D001644:Bifidobacterium; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000178:diet therapy*; D007778:Lactobacillus; D019936:Probiotics / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic