Probiotics
Mixed EvidenceLive bacteria to support gut health and immune function.
Not medical advice
Nutripedia summarises published peer-reviewed research. This content is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before taking any supplement.
Probiotics are live micro-organisms that confer health benefits when consumed in adequate amounts. Specific strains have evidence for improving digestive health, immune modulation, and may influence mood via the gut-brain axis.
Benefits are highly strain-specific. Good evidence for certain strains in IBS, antibiotic-associated diarrhoea, and immune support. Generic multi-strain products often lack clinical backing.
Evidence Database
Click any row to explore the studies behind each health outcome. Grades reflect the volume and quality of published research, not a recommendation.
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General Information
Dosage (Evidence-Reported)
These figures reflect what clinical studies used — not personalised recommendations.
Safety Notes
- Benefits are strain-specific — not all probiotics are equal
- Immunocompromised individuals should consult a doctor
- Initial bloating and gas may occur
- Refrigeration may be required for some products
Key Benefits
- May improve IBS symptoms (strain-dependent)
- Reduces antibiotic-associated diarrhoea
- Supports immune system modulation
- Potential mood benefits via gut-brain axis
Quick Facts
Nutripedia is an educational resource. Content is sourced from peer-reviewed studies and does not constitute medical advice. Consult a healthcare professional before starting any supplement.
The Evidence
15 peer-reviewed papers, updated yesterday
9 meta-analyses · 1 systematic review · 1 RCT · 1 cohort study · 3 position stands
Effects of Prebiotics and Probiotics on Symptoms of Depression and Anxiety in Clinically Diagnosed Samples: Systematic Review and Meta-analysis of Randomized Controlled Trials
Asad A, Kirk M, Zhu S et al.
Nutrition Reviews
Systematic review and meta-analysis found probiotics demonstrated a significant reduction in depression symptoms in clinically diagnosed populations; prebiotics showed a non-significant trend toward benefit. Probiotics also produced moderate improvements in anxiety scores. Authors recommend probiotics as an adjunctive intervention alongside standard psychiatric treatment, with effects likely mediated via the gut-brain axis.
High-dose Probiotic Mix of Lactobacillus spp., Bifidobacterium spp., Bacillus coagulans, and Saccharomyces boulardii to Prevent Antibiotic-associated Diarrhea in Adults: A Multicenter, Randomized, Double-blind, Placebo-controlled Trial (SPAADA)
Hodzhev V, Dzhambazov K, Sapundziev N et al.
Open Forum Infectious Diseases
Phase IV multicenter RCT (N=555) found high-dose multi-strain probiotic formulation significantly reduced AAD incidence versus placebo (9.2% vs 25.3%, p<0.001) in adults receiving broad-spectrum antibiotics. No clinically relevant differences in adverse events between groups. Results support high-dose multi-strain preparations for AAD prevention.
Efficacy and safety of probiotics in IBD: An overview of systematic reviews and updated meta-analysis of randomized controlled trials
Estevinho MM, Yuan Y, Rodríguez-Lago I et al.
United European Gastroenterology Journal
Overview of 22 systematic reviews and 45 RCTs (67 total studies) found probiotics beneficial for ulcerative colitis remission maintenance and pouchitis prevention, with multi-strain formulations appearing superior. No significant benefit was demonstrated for Crohn's disease. Safety profiles were comparable to placebo. Overall evidence certainty remained low.
World Gastroenterology Organisation Global Guidelines: Probiotics and Prebiotics
Guarner F, Sanders ME, Szajewska H et al.
Journal of Clinical Gastroenterology
Updated WGO global practice guidelines provide strain- and indication-specific recommendations for probiotic and prebiotic use across gastroenterological conditions. Guidelines require at least one adequately powered double-blind RCT per strain-indication pair. Recommendations cover IBS, AAD, acute diarrhoea, H. pylori, pouchitis, and paediatric conditions.
Additive efficacy and safety of probiotics in the treatment of ulcerative colitis: a systematic review and meta-analysis
Wang X, Zhou C, Zhang S et al.
European Journal of Nutrition
Meta-analysis of 13 RCTs (930 patients) found probiotic-assisted therapy was effective in inhibiting UC recurrence in patients in clinical remission, without increasing adverse events. For active UC, probiotics showed a trend toward improved remission induction but results were inconclusive. Multi-strain adjunctive approaches are recommended for remission maintenance.
Can the Evidence-Based Use of Probiotics (Notably Saccharomyces boulardii CNCM I-745 and Lactobacillus rhamnosus GG) Mitigate the Clinical Effects of Antibiotic-Associated Dysbiosis?
Waitzberg D, Guarner F, Hojsak I et al.
Advances in Therapy
Timely administration of an adequately dosed probiotic — specifically S. boulardii CNCM I-745 or L. rhamnosus GG — at antibiotic initiation or within 48 hours can prevent or resolve antibiotic-associated dysbiosis and support microbiota resilience in children and adults. Strain specificity and early timing are critical determinants of efficacy.
Probiotics for the management of irritable bowel syndrome: a systematic review and three-level meta-analysis
Chen M, Yuan L, Xie CR et al.
International Journal of Surgery
Meta-analysis of 72 RCTs demonstrated probiotics significantly improved global IBS symptom severity, abdominal pain, and quality of life versus placebo. Treatment duration and strain type were significant moderators; shorter interventions and Bacillus-based formulations yielded the largest effect sizes.
Efficacy of Probiotics in Irritable Bowel Syndrome: Systematic Review and Meta-analysis
Goodoory VC, Khasawneh M, Black CJ et al.
Gastroenterology
Analysis of 82 RCTs (10,332 patients) found moderate-certainty evidence that E. coli strains benefit global IBS symptoms; evidence for most other probiotic interventions was low to very low certainty. No significant safety concerns were identified. Evidence is insufficient to recommend specific strains as standard care.
Probiotics to prevent necrotising enterocolitis in very preterm or very low birth weight infants
Sharif S, Meader N, Oddie SJ et al.
Cochrane Database of Systematic Reviews
Cochrane review of 60 RCTs (11,156 infants) found probiotics may reduce necrotising enterocolitis risk (RR 0.54) and probably reduce all-cause mortality slightly (RR 0.77) in very preterm or very low birth weight infants. Evidence certainty was low to moderate; little or no effect was observed in extremely preterm infants. Further large trials are needed before routine clinical implementation.
Emerging issues in probiotic safety: 2023 perspectives
Merenstein D, Pot B, Leyer G et al.
Gut Microbes
International expert panel concluded that established practices adequately address traditional probiotic safety for healthy populations. Whole genome sequencing should be standard for safety assessment. Probiotic use requires caution in immunocompromised, critically ill, preterm, or elderly individuals due to rare but serious risks including bacteraemia and fungaemia. Rigorous adverse event reporting was recommended.
Probiotics for the Management of Pediatric Gastrointestinal Disorders: Position Paper of the ESPGHAN Special Interest Group on Gut Microbiota and Modifications
Szajewska H, Berni Canani R, Domellöf M et al.
Journal of Pediatric Gastroenterology and Nutrition
ESPGHAN position paper provides strain-specific recommendations for paediatric GI disorders including acute gastroenteritis, antibiotic-associated diarrhoea, nosocomial diarrhoea, NEC, H. pylori, functional abdominal pain, and colic. L. rhamnosus GG and S. boulardii received the strongest recommendations. Further research needed to define optimal dose and timing for most indications.
Efficacy of Probiotics for Irritable Bowel Syndrome: A Systematic Review and Network Meta-Analysis
Zhang T, Zhang C, Zhang J et al.
Frontiers in Cellular and Infection Microbiology
Network meta-analysis of 43 RCTs (5,531 patients) found Bacillus coagulans had the highest probability of being the optimal species for IBS symptom relief, global symptoms, abdominal pain, bloating, and straining. Eight-week treatment duration was associated with greater efficacy. Probiotic dose did not significantly influence outcomes.
Effect of Bifidobacterium longum 35624 on disease severity and quality of life in patients with irritable bowel syndrome
Sabaté JM, Iglicki F
World Journal of Gastroenterology
Prospective multicenter observational study found that 30 days of B. longum 35624 (one capsule/day) produced a significant reduction in IBS symptom severity from baseline; 57% of patients moved to lower severity categories or achieved remission. Quality of life improved and 63.8% of patients reported treatment satisfaction. No serious adverse events were recorded.
Probiotics for the prevention of antibiotic-associated diarrhoea: a systematic review and meta-analysis
Goodman C, Keating G, Georgousopoulou E et al.
BMJ Open
Co-administration of probiotics with antibiotics reduced the risk of antibiotic-associated diarrhoea by 37% across 42 studies (11,305 participants). Lactobacillus and Bifidobacterium species showed greatest effectiveness. Higher-dose formulations demonstrated superior protective effects compared to lower doses. Evidence quality was rated as moderate.
Probiotics for the Prevention of Antibiotic-associated Diarrhea in Adults: A Meta-Analysis of Randomized Placebo-Controlled Trials
Liao W, Chen C, Wen T et al.
Journal of Clinical Gastroenterology
Probiotics reduced antibiotic-associated diarrhoea incidence by 38% across 36 RCTs (9,312 participants). Initiating probiotics within two days of antibiotic prescription was most beneficial. No statistically significant increase in adverse events was observed, supporting safety in adults without immunodeficiency.