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Gut microbiota and immune regulation by Lactobacillus delbrueckii subsp. bulgaricus LB42: From preclinical safety assessment to clinical evidence.

  • 2026-01
  • Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association 207

Study Design

Type
Randomized Controlled Trial (RCT)
Population
In humans
Methods
genomic analysis, in vitro assays, and a randomized placebo-controlled clinical trial
Lactobacillus delbrueckii subsp. bulgaricus is a traditional yogurt starter widely recognized for its safety and gut health benefits. This study evaluated the safety and functional potential of Lactobacillus delbrueckii subsp. bulgaricus LB42 through genomic analysis, in vitro assays, and a randomized placebo-controlled clinical trial. Genomic screening confirmed the absence of pathogenic, resistance, or virulence genes. LB42 exhibited no cytotoxicity or hemolysis, showed broad antibiotic sensitivity, and adhered strongly to Caco-2 cells. Acute oral toxicity testing revealed no adverse effects in mice. In humans, LB42 was well tolerated without biochemical or hematological abnormalities, and no adverse events or allergic reactions were reported. LB42 supplementation significantly reduced Gastrointestinal Symptom Rating Scale and Pittsburgh Sleep Quality Index scores (p < 0.05), indicating improved gastrointestinal function and sleep quality, and lowered fecal calprotectin. Immune analyses demonstrated enhanced IgA and IgG responses (p < 0.05). Microbiota profiling revealed enrichment of short-chain fatty acid-producing genera (e.g., Lachnospira, Parabacteroides) and suppression of pro-inflammatory taxa (Enterococcus, Fusobacterium, Bilophila). Collectively, LB42 is genetically safe, well tolerated, and exerts dual benefits in enhancing host immunity and supporting microbial balance, supporting its potential as a clinically valuable probiotic strain with multifunctional benefits.

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