Bifidobacterium Longum Bl05
Also known as: B. longum, probiotic bifidobacteria, Bifidobacterium longum Bl-05, Bifidobacterium longum
Overview
Bifidobacterium longum is a Gram-positive anaerobic bacterium naturally found in the human gastrointestinal tract, particularly the colon. It is widely utilized as a probiotic supplement to support gut health and modulate immune function. The Bl-05 strain is a specific, clinically studied variant of B. longum, frequently incorporated into multi-strain probiotic formulations. Its primary applications include supporting individuals with inflammatory bowel diseases (IBD), irritable bowel syndrome (IBS), allergic rhinitis, respiratory infections, and exploring potential benefits for mood disorders. Research on B. longum is extensive, with numerous randomized controlled trials (RCTs) and some meta-analyses, although strain-specific data for Bl-05 is less abundant compared to other strains like BB536 or NCC3001. The quality of evidence ranges from moderate to high for gut-related outcomes, while evidence for immune and mood effects is promising but still developing.
Benefits
Bifidobacterium longum offers several evidence-based benefits. For gastrointestinal health, clinical trials, including those with B. longum 536, have shown its ability to reduce symptoms and inflammation in ulcerative colitis (UC) and IBS. For instance, B. longum 536 significantly reduced disease activity scores in mild to moderate UC patients after 8 weeks and decreased proinflammatory cytokines (IL-6, IL-8, TNF-α) while improving intestinal permeability in IBS-D patients over 12 weeks. In terms of immune modulation, B. longum BB536 has been shown to reduce the duration of upper respiratory symptoms (e.g., sore throat by 46%) in children and improve symptoms of allergic rhinitis, although some studies had smaller sample sizes. Preliminary exploratory studies with B. longum NCC3001 suggest potential improvements in mood and mental health, but this area requires larger, more robust RCTs. The observed effect sizes vary by condition and specific strain but indicate clinically meaningful improvements in inflammation, symptom scores, and overall quality of life. Benefits typically become apparent after 4 to 12 weeks of consistent supplementation.
How it works
Bifidobacterium longum exerts its effects primarily by modulating the gut microbiota composition, fostering the growth of beneficial bacteria like Faecalibacterium, and enhancing the integrity of the gut barrier. It actively reduces the production of proinflammatory cytokines such as IL-6, IL-8, and TNF-α, while simultaneously increasing anti-inflammatory mediators, which contributes to its anti-inflammatory effects in the intestine. The probiotic also interacts with the mucosal immune system, promoting regulatory T cell responses and modulating systemic immunity, which may explain its benefits in allergic and respiratory conditions. Certain strains of B. longum produce beneficial metabolites, including short-chain fatty acids (SCFAs), which are known to influence gut-brain axis signaling and potentially impact mood. The oral bioavailability and efficacy of B. longum depend on its survival through the acidic stomach environment and its ability to colonize the intestine; encapsulation and co-administration with prebiotics like inulin can significantly enhance these factors.
Side effects
Bifidobacterium longum is generally considered safe for human consumption, with a long history of use. The most common side effects are mild and infrequent, typically involving transient gastrointestinal symptoms such as bloating or gas, which occur in less than 5% of users. High-quality randomized controlled trials have not reported any serious adverse events or contraindications associated with its use. There are no significant drug interactions documented for B. longum. While generally safe, special populations, including infants and immunocompromised individuals, should use B. longum under medical supervision, although studies in children have consistently demonstrated good tolerability. Overall, its safety profile is robust, making it a well-tolerated supplement for most individuals.
Dosage
Effective dosages of Bifidobacterium longum in clinical trials vary depending on the specific strain and the intended health indication, but typically range from 1 billion to 10 billion Colony Forming Units (CFU) per day. For instance, B. longum BB536 has been administered for up to 10 months in children at doses sufficient to reduce respiratory symptoms. The duration of supplementation required to achieve clinical benefits ranges from as short as 4 weeks for gut inflammation to several months for immune modulation. Co-administration with prebiotics, such as inulin, may enhance the colonization and overall efficacy of the probiotic. While the timing relative to meals is not strictly defined, taking probiotics with food may improve their survival through the gastric acid environment, thereby enhancing their effectiveness.
FAQs
Is B. longum Bl-05 effective alone or only in combination?
Evidence supports both single-strain and multi-strain formulations. Some benefits may be enhanced when combined with prebiotics or other probiotic strains.
How soon can benefits be expected?
Improvements in gut symptoms often appear within 4–8 weeks. Immune and mood-related benefits may require a longer duration of consistent supplementation.
Is it safe for children?
Yes, multiple randomized controlled trials in children have demonstrated the safety and efficacy of B. longum, though specific doses and strains may vary.
Can it replace medication for IBD or allergies?
No, B. longum is considered an adjunctive therapy. It should not replace standard medical treatments for conditions like IBD or allergies.
Research Sources
- https://pmc.ncbi.nlm.nih.gov/articles/PMC8324359/ – This review and collection of RCTs highlights that B. longum 536 effectively reduced disease activity in ulcerative colitis and decreased proinflammatory cytokines in IBS-D, while also improving gut barrier function. The studies showed consistent results despite some heterogeneity in protocols and occasional combination with other strains or prebiotics.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC10012958/ – This review of RCTs indicates that B. longum BB536 reduced respiratory symptoms in children and improved allergic rhinitis symptoms, alongside increasing beneficial gut bacteria. While well-controlled, some trials had small sample sizes, suggesting a need for larger confirmatory studies.
- https://www.nature.com/articles/s41598-025-95651-1 – This exploratory RCT provides preliminary evidence that B. longum NCC3001 may contribute to mood improvement, suggesting potential gut-brain axis effects. However, due to its exploratory design and small sample size, these findings require replication in larger studies.
- https://all-imm.com/index.php/aei/article/download/507/824/6107 – This source, likely a review or research article, discusses the broader immunological effects of B. longum, including its role in modulating immune responses and its potential in allergic conditions. It reinforces the understanding of B. longum's mechanism of action in immune system regulation.
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