The Effect of Probiotics on Gut Microbiota Changes in Healthy Chinese Adults During Short-Term European Travel: A Randomised, Double-Blind, Placebo-Controlled Clinical Trial

Inclusion criteria: 1. Aged 18-65 years, regardless of gender; 2. Planning to undertake a short-term round-trip journey to Europe (within 7 days); 3. Able to understand and willing to comply with the study protocol, and to cooperate with study procedures; 4. Voluntarily sign the informed consent form before any study-related procedures are initiated. Exclusion criteria: 1. Diseases that may affect the evaluation of trial results, such as immune dysfunction, severe renal/hepatic dysfunction, severe cardiovascular disease, malignant tumors, acute or chronic infections, etc.; 2. Use of probiotic preparations, antibiotics, hormones, immunosuppressants, biological agents, or JAK inhibitors within 4 weeks; 3. Subjects with diagnosed or uncontrolled parasitic infections; 4. Patients receiving long-term medication for chronic diseases; 5. Patients with severe organic lesions in the thyroid, heart, brain, lungs, kidneys, or musculoskeletal system; 6. Patients with a history of or currently diagnosed mental illness; 7. Patients on long-term corticosteroid therapy; 8. Use of growth hormone, γ-aminobutyric acid (GABA), lysine, inositol, or vitamin B12; 9. Presence of uncontrolled, clinically significant laboratory abnormalities that may affect data interpretation or subject participation; 10. Participation in other clinical intervention studies involving drugs, dietary supplements, probiotics, or prebiotics within the past 4 weeks; 11. Presence of severe infections or major trauma deemed by the investigator to potentially affect outcomes, or having undergone moderate to major surgery within the past month; 12. Known allergy to any component of the probiotic product; 13. Subjects deemed unsuitable for participation by the investigator for any other reason.