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Probiotic supplementation (IBS-focused evidence)

Multi-strain and single-strain probiotic preparations have been tested against placebo in dozens of adult IBS randomised trials; updated meta-analyses report heterogeneous benefits and GRADE certainty that is often low to very low depending on strain and endpoint.

Scope

Probiotic supplementation here indexes live-microorganism preparations swallowed for irritable bowel syndrome (IBS) symptom endpoints—not faecal microbiota transplantation regulatory protocols, fermented-food-only interventions unless trialised as defined strains, or antibiotic comparators.

Evidence anchors (PubMed)

  • Strain-tiered MA update: Goodoory et al. 2023 (Gastroenterology; PMID 37541528; goodoory-2023-probiotics-ibs-meta-gastroenterology) — 82 RCTs (n = 10,332); GRADE ranges from moderate (Escherichia strains for global symptoms) down to very low for many combination products; adverse-event pooled risk not significantly higher across 55 AE-reporting trials.

Distinct protocols

  • Marine omega-3 (marine-omega-3-supplementation) — different mechanism trials.
  • Magnesium (magnesium-supplementation) — mineral motility/sleep adjacent narratives, not probiotic colonisation claims.

Evidence hygiene

Strain identity matters—do not merge 299V evidence with unrelated Bacillus trade-name blends without reading the MA strata.

Evidence