Bifidobacterium infantis 35624
Bifidobacterium longum subsp. infantis 35624
The flagship IBS strain — immune-modulating Bifidobacterium with landmark trial evidence
Evidence tier
Moderate
Research weight
Citations
11 verified / 11
Classification
Probiotics
❝
What the evidence says. Several controlled trials; effects real but modest or context-dependent.
What is Bifidobacterium infantis 35624?
Bifidobacterium infantis 35624 (Bifidobacterium longum subsp. infantis 35624) is a probiotic strain used for eases overall ibs symptoms (abdominal pain, bloating, bowel dysfunction) at 1x10^8 cfu/day in double-blind rcts. NutriDex grades the human evidence as Moderate. Bifidobacterium 35624 (originally B. infantis 35624, reclassified after genome sequencing as B. longum subsp. longum 35624; sold as Align/Bifantis) is the best-studied single strain for irritable bowel syndrome (IBS). Two landmark double-blind RCTs (O'Mahony 2005, n=77; Whorwell 2006, n=362 women) found that 1x10^8 CFU/day significantly reduced abdominal pain, bloating, bowel dysfunction and global symptoms versus placebo, with the benefit linked to normalization of a pro-inflammatory IL-10/IL-12 cytokine ratio. Evidence is graded moderate rather than strong because a 2017 meta-analysis found the pooled single-strain effect on individual symptoms was not statistically significant, even though more recent open-label and pediatric studies report large IBS-SSS reductions. Effects are strain-specific and should not be generalized to other bifidobacteria.
Purported Benefits
✓Eases overall IBS symptoms (abdominal pain, bloating, bowel dysfunction) at 1x10^8 CFU/day in double-blind RCTs
✓Reduces abdominal pain/discomfort versus placebo across most treatment weeks (O'Mahony 2005)
✓Improves global IBS symptom assessment by >20% over placebo (Whorwell 2006)
✓Reduces functional abdominal bloating/distention
✓Normalizes a pro-inflammatory IL-10/IL-12 cytokine ratio, indicating an immune-modulating mechanism
✓Lowers IBS Severity Scoring System (IBS-SSS) scores in adults and in children/adolescents in real-world studies
Evidence by outcome
The same supplement can be well-proven for one use and unproven for another — here is the human evidence graded outcome by outcome.
| Outcome | Evidence | Effect | Studies |
|---|---|---|---|
| Eases overall IBS symptoms (pain, bloating, bowel dysfunction)Two landmark RCTs positive, but a 2017 meta-analysis found pooled single-strain effect on individual symptoms non-significant. | Mixed | ↔ mixed · moderate | 3 |
| Reduces abdominal pain/discomfort vs placeboO'Mahony 2005 and a 2026 meta-analysis support it, yet the 2017 meta-analysis showed no significant pain benefit. | Mixed | ↔ mixed · moderate | 3 |
| Reduces functional abdominal bloating/distention2017 meta-analysis found small significant bloating benefit, but a 2025 triple-blind RCT found none. | Mixed | ↔ mixed · small | 3 |
| Normalizes pro-inflammatory IL-10/IL-12 cytokine ratioSingle RCT mechanistic finding; immune-modulation marker, not a clinical endpoint. | Preliminary | ↑ benefit | 1 |
Dosing & Compounds
Typical Dose
1x10^8 CFU/day (the dose that outperformed both placebo and higher 1x10^10 doses in the Whorwell 2006 dose-ranging trial); typically one capsule once daily, taken for at least 4-8 weeks; benefit is lost after discontinuation, so continued daily use is needed.
Active Compounds
Safety & Cautions
Well tolerated in trials; adverse events were comparable to placebo, with rare mild nausea reported. No serious adverse events in IBS or pediatric studies; 89% of participants rated tolerability good to very good. As with any live probiotic, exercise caution in critically ill, immunocompromised patients, or those with central venous catheters, where translocation/bacteremia is a theoretical concern; bifidobacteremia is exceedingly rare. Educational only — always check with your doctor or pharmacist before combining Bifidobacterium infantis 35624 with any medicine.
Key Studies ★ 11 studies
Meta-analysis
Cichońska-Bień 2026
✓ Full text
Strain-specific meta-analysis of 32 RCTs (10 strains); B. longum (B. infantis) 35624 across 3 trials significantly reduced abdominal pain severity, straining, and overall IBS symptoms, but showed insufficient effect on bloating, urgency, incomplete evacuation, and gas passage.
Systematic review
Goodoory/Ford 2023
✓ PubMed
Systematic review and meta-analysis of 82 RCTs (10,332 IBS patients) found combination probiotics, but limited single-strain evidence, improved global IBS symptoms; overall efficacy graded low certainty with substantial heterogeneity.
Meta-analysis
Nutrients NMA 2023
✓ Full text
Outcome-specific network meta-analysis of probiotic strains/mixtures in IBS (search to June 2023) ranked Lactobacillus acidophilus DDS-1 first for IBS-SSS improvement; B. infantis 35624 as a single strain was not among the top-ranked strains.
Meta-analysis
Yuan 2017
✓ PubMed
Meta-analysis (6 studies, ~796 IBS patients) found single-strain B. infantis 35624 did not significantly improve abdominal pain or bowel-habit satisfaction, though pooled bloating/distention improvement remained significant (SMD 0.21; 95% CI 0.07-0.35).
RCT
Springer FAB RCT 2025
✓ Source
Triple-blind, placebo-controlled trial of B. infantis 35624 (1x10^8 CFU, 4 weeks) in functional abdominal bloating found no significant improvement in bloating, other abdominal symptoms, or quality of life versus placebo; both arms well tolerated.
RCT
O'Mahony 2005
✓ PubMed
In 77 IBS patients, B. infantis 35624 (1x10^10 CFU/day, 8 wk) significantly reduced abdominal pain, bloating and bowel-movement difficulty vs placebo and normalized the abnormal IL-10/IL-12 (anti-/pro-inflammatory) cytokine ratio.
RCT
Whorwell 2006
✓ PubMed
Double-blind dose-ranging RCT in 362 women with IBS: 1x10^8 CFU/day was superior to placebo and other doses for abdominal pain plus composite scores for bloating, bowel dysfunction, straining and gas, exceeding placebo by >20% on global assessment.
Observational study
Lenoir 2023
✓ Full text
Open-label 8-week post-market study (n=33 per-protocol) of B. longum 35624: Total IBS Symptom Score fell 43.5% (p<0.0001) and IBS-SSS dropped ~82 points (p<0.001); >60% achieved clinically meaningful improvement with good tolerability.
Observational study
Cruchet Munoz 2024
✓ Full text
Real-world open-label study in 64 children/adolescents (8-18 y, 1x10^9 CFU/day, 12 wk): mean IBS-SSS fell from 334 to 58 (p<0.0001) with 96.6% reaching clinically significant improvement; symptoms rebounded after washout.
Review
Quigley 2017
✓ Source
Narrative/strain-specificity review summarizing the 35624 evidence base and mechanisms (mucosal binding, reduced barrier dysfunction, immunoregulation) and confirming probiotic effects are strain-specific.
Genomic study
Altmann 2016
✓ Full text
Genome sequencing and phylogenetic analysis reclassified strain 35624 from B. longum subsp. infantis to B. longum subsp. longum and characterized its mucosa-binding exopolysaccharide.