Supplementary file 1_Bifidobacterium supplementation maintains gut microbiota stability and enhances well-being during short-term travel.docx

BackgroundInternational travel exposes individuals to abrupt environmental, dietary, and circadian changes that can disturb gut microbiota and overall well-being. While probiotics are known to support gastrointestinal and systemic health, their effects during short-term travel remain incompletely characterized in randomized trials.
MethodsThis randomized, double-blind, placebo-controlled study investigated whether a multi-strain Bifidobacterium probiotic could maintain gut microbiota stability and support health during a five-day trip from China to Japan. Forty healthy adults were randomly assigned to receive either probiotic (n = 22) or placebo (n = 18) daily from Day 1 to Day 4. Stool samples collected before departure (Day 0) and after return (Day 5) were analyzed by metagenomic sequencing, quantitative PCR, and fecal secretory immunoglobulin A (sIgA) assays. Participants completed validated questionnaires on gastrointestinal and respiratory symptoms, sleep quality (PSQI), anxiety (GAD-7), and well-being (WHO-5).
ResultsCompared with placebo, participants receiving the probiotic showed maintenance of microbial diversity (Chao1 and Fisher indices, both p = 0.044), prevented enrichment of potentially harmful taxa (Bilophila, Flavonifractor), and increased Bifidobacterium abundance. Clinically, the probiotic group reported fewer respiratory and systemic symptoms, including sore throat (p = 0.034) and fatigue (p = 0.043). Sleep quality also improved, with longer sleep duration (p = 0.023), fewer total occurrence days of PSQI >5 (p = 0.009), lower anxiety scores (p = 0.001) and higher WHO-5 well-being scores (p = 0.041). Functional profiling showed up-regulation of vitamin biosynthesis pathways (folate, biotin, retinol) and decreased antibiotic resistance gene prevalence.
ConclusionShort-term probiotic administration demonstrated gut microbiota resilience and improved physiological and psychological stability during travel. Probiotics may serve as an accessible strategy to support well-being under transient environmental and lifestyle stress.
Clinical trial registrationClinicalTrials.gov, identifier NCT07163819.