Supplement

Probiotics

Also known as Lactobacillus, Bifidobacterium, Saccharomyces boulardii

Live microorganisms, commonly Lactobacillus and Bifidobacterium strains, that colonise the gut and influence digestion and immune signalling via short-chain fatty acid production; effects are strain- and dose-specific.

2linked conditions

10linked studies

On this pageEvidence Availability Outcomes & conditions →

Evidence

What the research actually shows

We link to relevant studies and leave interpretation to you and your healthcare professional.

Evidence analytics

Where the evidence is concentrated

Number of audited published findings for Probiotics by condition. Drill into a pair page for the full breakdown.

Putative uses

Where people report using it and what trials suggest

Strong evidenceAntibiotic-associated diarrhoea prevention (L. rhamnosus GG, S. boulardii)
Moderate evidenceIBS symptom relief (specific strains: Bifidobacterium 35624 etc.)
Strong evidenceNecrotising enterocolitis risk in preterm infants (in hospital)

Where the evidence is negative

Common claims the trials do not support

General 'immunity/energy/wellbeing' claims not supported.
Many retail products contain strains never tested for the buyer's condition.
May delay gut microbiome reconstitution after antibiotics (2018 finding).

Live microorganisms with strain- and condition-specific evidence; benefit depends entirely on matching the right strain to the right condition.

Safety notes: Generally safe; rare infections in immunocompromised/CVC patients — avoid in those groups without medical advice.

Evidence grades reflect study quality and consistency, not marketing claims.

10studies referenced

9journals

2020–2025publication range

01The Effect of Probiotics on Health in Pregnancy and Infants: A Randomized, Double-Blind, Placebo-Controlled TrialBinda S, et al. · Nutrients · 2025PMID 40507094 ↗02Bifidobacterium and Lactobacillus Probiotics and Gut Dysbiosis in Preterm Infants: The PRIMAL Randomized Clinical TrialVan Rossum T, et al. · JAMA pediatrics · 2024PMID 39102225 ↗03Probiotic, prebiotic, synbiotic and fermented food supplementation in psychiatric disorders: A systematic review of clinical trialsRibera C, et al. · Neuroscience and biobehavioral reviews · 2024PMID 38280441 ↗04Efficacy and safety of topical Streptococcus postbiotic emollient in adolescents and adults with mild-to-moderate atopic dermatitis: A randomized, double-blind, vehicle-controlled trialKim MS, et al. · Allergy · 2024PMID 38436460 ↗05Probiotics fortify intestinal barrier function: a systematic review and meta-analysis of randomized trialsZheng Y, et al. · Frontiers in immunology · 2023PMID 37168869 ↗06Effect of synbiotic supplementation on immune parameters and gut microbiota in healthy adults: a double-blind randomized controlled trial

Search PubMed ↗Find clinical trials ↗

What trials found, in numbers

Summaries of published trial results for this compound, grouped by condition. Numbers are reported exactly as the researchers published them — we never calculate or convert.

How to read this table

Benefit: What the trial saw happen: whether the measured outcome moved in the helpful direction in that one study (the tag on each row: “Benefit seen”, “No clear benefit” or “Unclear”). It is a study result — not advice, and not a promise it will work for you.
Evidence: How strong the research behind that result is. A meta-analysis pools many studies (strongest); a systematic review collates them; an RCT tests against a control (placebo); observational studies only watch — they can suggest, not prove.
Effect size: How large the measured change was, exactly as the researchers published it. “No number reported” means the abstract gave no effect size — we never invent one.

In short: benefit is what was observed; evidence is how much you should trust the observation. A “Benefit seen” tag on a weak study counts for far less than the same tag on a meta-analysis.

Immune Support (3 outcomes)

Outcome measured	What trials found	Effect size	People studied	Duration	Type of evidence	Study
immunoregulatory galectin-1	Galectin-1 was upregulated in Th2 and Th17 cells in infants supplemented with Bifidobacterium infantis EVC001 compared to those lacking bifidobacteria.Benefit seen	no number reported	—	first months of life	RCT · 2021	PMID 34143954
interferon beta (IFN-beta)	Interferon beta was induced in breastfed infants given Bifidobacterium infantis EVC001 compared to those lacking bifidobacteria.Benefit seen	no number reported	—	first months of life	RCT · 2021	PMID 34143954

Outcomes & conditions

Why people look into Probiotics — and what they report

Associated conditions and community-reported outcomes, wrapped together on one page. Aggregates appear only once enough reports arrive.

Outcomes & conditions →

Important: This page reflects observational, aggregate-only community reporting and independent published research. It is not medical advice, and it does not claim any compound treats, cures, or is effective for any condition. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or treatment.

Availability

Where to get Probiotics (UK)

How this compound is sold in the UK, and where our readers typically find it.

Retailer search links — we may earn commission on purchases at no cost to you. Commission never affects our evidence ratings.

Search Probiotics on Amazon UK →Search Probiotics on Holland & Barrett →Search Probiotics on iHerb →