The Effect of a Probiotic on Gut Microbiota Stability and Systemic Well-Being during Short-Term Travel

Short-term travel, particularly to new environments, can disrupt gut microbiota homeostasis and induce a range of physical and psychological symptoms. While probiotics are proposed to mitigate these effects, evidence from well-controlled trials during domestic travel, especially along unique routes like China's Silk Road, remains limited. This study investigated the efficacy of a multi-strain Bifidobacterium probiotic in maintaining gut microbiota stability and alleviating travel-related symptoms. In a randomized, double-blind, placebo-controlled trial, 74 healthy adults traveling to Xinjiang were assigned to receive either a probiotic (n = 39; B. longum subsp. infantis M-63, B. breve M-16V, and B. longum BB536, 1.5 × 10⁹ CFU/day) or a placebo (n = 35) for five days during travel. Gut microbiota was profiled via metagenomic sequencing (pre- and post-travel), and symptoms were recorded daily. Primary outcomes were changes in gut microbiota composition and function (KEGG pathways). Secondary outcomes included respiratory, gastrointestinal, and systemic symptom scores. Data were analyzed on an intention-to-treat basis. While alpha and beta diversity remained stable in both groups, the probiotic group exhibited a distinct post-travel microbiota enriched with beneficial taxa, including Bifidobacterium breve and Intestinibacillus at the genus level, and Lacticaseibacillus rhamnosus, Lacticaseibacillus paracasei, and other Lacticaseibacillus species. qPCR confirmed significant increases in administered strains B. longum subsp. infantis (p < 0.001) and B. breve (p < 0.001). KEGG analysis revealed that the probiotic group maintained a metabolically focused profile (e.g., peptidoglycan biosynthesis, histidine metabolism), whereas the placebo group showed increased abundance of microbial pathways associated with host disease-related signaling (e.g., Huntington disease, various cancers) and inflammatory signaling (e.g., PI3K-Akt signaling pathway). Symptomatically, the probiotic group demonstrated a significantly greater reduction than the placebo in irritability (-92% vs. -31%; p = 0.033) and fatigue (-24% vs. +43%; p = 0.024) post-travel, and reported less dizziness (-100% vs. -35%; p = 0.024). Supplementation with a multi-strain Bifidobacterium probiotic during short-term travel promoted the colonization of beneficial bacteria, stabilized gut microbial function against travel-induced dysregulation, and may contribute to supporting systemic well-being during travel.