Effects of probiotics on gut microbiota, IBS symptoms, and immune function: a meta-analysis
Ford ACQuigley EMLacy BELembo AJSaito YASchiller LRSoffer EESpiegel BMMoayyedi P
Evidence is still building up
Summary
A meta-analysis of 43 RCTs. Probiotics significantly improved global IBS symptom scores and abdominal pain compared to placebo (risk ratio 0.79). However, effects varied considerably by strain, with more consistent improvements seen in multi-strain Lactobacillus and Bifidobacterium products. Multiple studies also reported improvements in immune markers, including secretory IgA and inflammatory cytokines.
Key findings
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Significantly improved global IBS symptom scores vs placebo (RR 0.79)
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Significant reduction in abdominal pain and bloating
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High strain specificity — not all probiotic products are equally effective
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Improvements in immune markers (secretory IgA) reported in multiple studies
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Improvement in IBS symptoms and abdominal pain reported in meta-analysis (strain-dependent)
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Last checked: 2026-06-24