Keystone Species Restoration: Therapeutic Effects of Bifidobacterium infantis and Lactobacillus reuteri on Metabolic Regulation and Gut–Brain Axis Signaling—A Qualitative Systematic Review (QualSR)
Bibliographic record
Abstract
Background: The human gut microbiome—a diverse ecosystem of trillions of microorganisms—plays an essential role in metabolic, immune, and neurological regulation. However, modern lifestyle factors such as antibiotic overuse, cesarean delivery, reduced breastfeeding, processed and high-sodium diets, alcohol intake, smoking, and exposure to environmental toxins (e.g., glyphosate) significantly reduce microbial diversity. Loss of keystone species like Bifidobacterium infantis (B. infantis) and Lactobacillus reuteri (L. reuteri) contributes to gut dysbiosis, which has been implicated in chronic metabolic, autoimmune, cardiovascular, and neurodegenerative conditions. Materials and Methods: This Qualitative Systematic Review (QualSR) synthesized data from over 547 studies involving human participants and standardized microbiome analysis techniques, including 16S rRNA sequencing and metagenomics. Studies were reviewed for microbial composition, immune and metabolic biomarkers, and clinical outcomes related to microbiome restoration strategies. Results: Multiple cohort studies have consistently reported a 40–60% reduction in microbial diversity among Western populations compared to traditional societies, particularly affecting short-chain fatty acid (SCFA)-producing bacteria. Supplementation with B. infantis is associated with a significant reduction in systemic inflammation—including a 50% decrease in C-reactive protein (CRP) and reduced tumor necrosis factor-alpha (TNF-α) levels—alongside increases in regulatory T cells and anti-inflammatory cytokines interleukin-10 (IL-10) and transforming growth factor-beta 1 (TGF-β1). L. reuteri demonstrates immunomodulatory and neurobehavioral benefits in preclinical models, while both probiotics enhance epithelial barrier integrity in a strain- and context-specific manner. In murine colitis, B. infantis increases ZO-1 expression by ~35%, and L. reuteri improves occludin and claudin-1 localization, suggesting that keystone restoration strengthens barrier function through tight-junction modulation. Conclusions: Together, these findings support keystone species restoration with B. infantis and L. reuteri as a promising adjunctive strategy to reduce systemic inflammation, reinforce gut barrier integrity, and modulate gut–brain axis (GBA) signaling, indicating translational potential in metabolic and neuroimmune disorders. Future research should emphasize personalized microbiome profiling, long-term outcomes, and transgenerational effects of early-life microbial disruption.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.015 | 0.042 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.005 | 0.007 |
| Bibliometrics | 0.010 | 0.008 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".