Entry 19

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Bifidobacterium longum subsp. infantis 35624: B. infantis 35624

Bifidobacterium longum subsp. infantis 35624: B. infantis 35624

Consumes human milk oligosaccharides to produce anti-inflammatory metabolites, reducing IBS symptoms with RCT support.

Gastrointestinal

immunological

Evidence strength

5 / 5

?

Overview

B. longum subsp. infantis 35624 is one of the most studied single-strain probiotics for irritable bowel syndrome (IBS). Multiple RCTs and meta-analyses (pools results from multiple trials) support its use for reducing abdominal pain, bloating, and bowel habit problems [1,2]. The strain was originally isolated from healthy human intestinal mucosa. It was developed at University College Cork [3]. It is commercially available as Align (Procter & Gamble) in capsule format [4].

Mechanism

B. infantis 35624 tunes the immune system. It induces Foxp3+ regulatory T cells and changes dendritic cell function [5,6]. The strain reduces NF-κB activation in cells lining the gut. It lowers production of pro-inflammatory cytokines (TNF-α, IL-8, IL-12). It promotes IL-10 secretion [7,8]. Fecal recovery studies confirm the strain survives gastrointestinal transit. It transiently colonizes the gut during supplementation [4]. The strain also tunes the immune system beyond the gut. Oral administration changed plasma cytokine profiles in psoriasis patients [6].

Health Benefits

A meta-analysis (pools results from multiple trials) of five RCTs (n=436) confirmed B. infantis 35624 significantly improves overall IBS symptoms compared to placebo (RR 1.58; 95% CI 1.21–2.06) [2]. The landmark multicenter RCT by Whorwell et al. (n=362 women) showed significant reduction in abdominal pain, discomfort, bloating, and bowel movement difficulty at the 1×10^8 CFU (colony-forming units, a live bacteria count) dose [1] [RCT]. A 2017 multicenter RCT (n=302) in non-patient volunteers with abdominal discomfort and bloating showed significant reduction in bloating scores (P=0.04) [3] [RCT]. A 2022 pilot RCT (n=40) in uncontrolled asthma patients reported improved Asthma Control Test scores with supplementation [small RCT, n=40, PMID:36089255]. A 2026 strain-specific systematic review with meta-analysis ranked B. infantis 35624 among probiotics with evidence for IBS symptom improvement [7] [systematic review + meta-analysis]. Evidence for fibromyalgia and chronic fatigue syndrome is preliminary [9] [systematic review, low-quality evidence].

Biology

Taxonomy follows the Mattarelli et al. (2008) reclassification. The strain is classified as B. longum subsp. infantis comb. nov., formerly Bifidobacterium infantis [10]. It is Gram-positive, only grows without oxygen, non-motile, and non-spore-forming. It is a rod-shaped bacterium. It ferments sugars via the fructose-6-phosphate phosphoketolase (bifid shunt) pathway. This produces acetate and lactate as the main end-products. Its natural habitat is the infant gastrointestinal tract. It is specialized for utilizing human milk oligosaccharides (special sugars in breast milk).

Bibliography

  1. Whorwell PJ, Altringer L, Morel J, Bond Y, Charbonneau D, O’Mahony L, et al. (2006). Efficacy of an encapsulated probiotic Bifidobacterium infantis 35624 in women with irritable bowel syndrome. Am J Gastroenterol. 101(7):1581-90. PMID: 16863564

  2. Yuan F, Ni H, Asche CV, Kim M, Walayat S, Ren J. (2017). Efficacy of Bifidobacterium infantis 35624 in patients with irritable bowel syndrome: a meta-analysis. Curr Med Res Opin. 33(7):1191-1197. PMID: 28166427

  3. Ringel-Kulka T, McRorie J, Ringel Y. (2017). Multi-Center, Double-Blind, Randomized, Placebo-Controlled, Parallel-Group Study to Evaluate the Benefit of the Probiotic Bifidobacterium infantis 35624 in Non-Patients With Symptoms of Abdominal Discomfort and Bloating. Am J Gastroenterol. 112(1):145-151. PMID: 27845337

  4. Charbonneau D, Gibb RD, Quigley EM. (2013). Fecal excretion of Bifidobacterium infantis 35624 and changes in fecal microbiota after eight weeks of oral supplementation with encapsulated probiotic. Gut Microbes. 4(3):201-11. PMID: 23549409

  5. Konieczna P, Akdis CA, Quigley EM, Shanahan F, O’Mahony L. (2012). Portrait of an immunoregulatory Bifidobacterium. Gut Microbes. 3(3):261-6. PMID: 22572827

  6. Groeger D, O’Mahony L, Murphy EF, Bourke JF, Dinan TG, Kiely B, et al. (2013). Bifidobacterium infantis 35624 modulates host inflammatory processes beyond the gut. Gut Microbes. 4(4):325-39. PMID: 23842110

  7. Maslennikov R, Gosteeva E, Ananeva V, Korshunova L, Kravtsowa A, Poluektova E, et al. (2026). Strain-Specific Systematic Review with Meta-Analysis of Probiotics Efficacy in the Treatment of Irritable Bowel Syndrome. J Clin Med. 15(3):1152. PMID: 41682832

  8. O’Hara AM, O’Regan P, Fanning A, O’Mahony C, Macsharry J, Lyons A, et al. (2006). Functional modulation of human intestinal epithelial cell responses by Bifidobacterium infantis and Lactobacillus salivarius. Immunology. 118(2):202-15. PMID: 16771855

  9. Roman P, Carrillo-Trabalon F, Sanchez-Labraca N, Canadas F, Estevez AF, Cardona D. (2018). Are probiotic treatments useful on fibromyalgia syndrome or chronic fatigue syndrome patients? A systematic review. Benef Microbes. 9(4):603-611. PMID: 29695180

  10. Mattarelli P, Bonaparte C, Pot B, Biavati B. (2008). Proposal to reclassify the three biotypes of Bifidobacterium longum as three subspecies: Bifidobacterium longum subsp. longum subsp. nov., Bifidobacterium longum subsp. infantis comb. nov. and Bifidobacterium longum subsp. suis comb. nov. Int J Syst Evol Microbiol. 58(Pt 4):767-72. PMID: 18398167

Available Products

Align Probiotic (Procter & Gamble) is a capsule containing 1×10^9 CFU of B. infantis 35624. It is marketed for digestive health with IBS-related claims in the US [1,4]. It was previously distributed under license by various regional partners.

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