With the improvement of living standards, travel has become a common form of leisure. However, travelers often face changes in living environments, dietary habits, and sleep schedules, all of which can impact the gut microbiota and lead to a range of health issues.

Dietary changes during travel are one of the key factors affecting gut microbiota. Food composition and preparation methods vary widely across regions, introducing novel bacterial strains into the gut. These new strains may compete with the host's indigenous microbiota, causing dysbiosis and gastrointestinal problems such as traveler's diarrhea. Additionally, high-fat diets and low-fiber intake can disrupt gut microbial balance, leading to constipation. Beyond diet, jet lag, stress, and hygiene conditions also influence gut microbiota. For example, frequent cross-time-zone travel disrupts the circadian rhythm of the gut microbiome, impairing the host's metabolic health. Furthermore, exposure to contaminated water or food during travel may introduce pathogenic bacteria such as Escherichia coli, Shigella, and Campylobacter, which can disrupt gut homeostasis and cause gastrointestinal infections.

Changes in gut microbiota not only affect gastrointestinal health but may also trigger respiratory and allergic symptoms. Studies have shown a close relationship between gut microbiota and the immune system; gut dysbiosis can lead to immune dysfunction, increasing the risk of respiratory infections. Additionally, alterations in gut microbiota may influence allergic responses, with exposure to new environments and foods during travel potentially exacerbating allergic symptoms.

Probiotics-live microorganisms that confer health benefits to the host when administered in adequate amounts-have garnered widespread attention for their potential to enhance human health. These beneficial microbes, primarily from the genera Lactobacillus and Bifidobacterium, promote gut health by modulating the gut microbiome, supporting immune function, and improving digestion. Research indicates that probiotics can alleviate symptoms of gastrointestinal disorders such as irritable bowel syndrome and inflammatory bowel disease, while also enhancing overall immunity and reducing infection risk. Furthermore, their role in regulating the gut-brain axis highlights their potential to improve mental health. Therefore, rational probiotic supplementation to maintain gut microbiota balance is of great significance for promoting human health.

This study aims to evaluate the efficacy of probiotics in maintaining gut microbial balance and improving health outcomes during short-term travel. By assessing microbial composition, immune markers (e.g., sIgA), respiratory symptoms, allergic and gastrointestinal symptoms, anxiety disorders, sleep quality, and well-being indices, the study seeks to demonstrate the benefits of probiotic supplementation in mitigating travel-related health issues.

Inclusion Criteria:

1. Age: 18-65 years, inclusive, with no restriction on gender.
2. Planned short-term round-trip travel from China to an overseas destination, with a total travel duration of no more than 7 days.
3. Volunteers must be able to understand and comply with the study protocol, and provide written informed consent prior to initiation of any study procedures.

Exclusion Criteria:

1. Diseases that may affect the evaluation of trial results, including but not limited to immune dysfunction, severe renal/hepatic impairment, 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 prior to enrollment.
3. Subjects with confirmed or uncontrolled parasitic infections.
4. ① Patients receiving long-term medication for chronic diseases; ② Patients with severe organic lesions of the thyroid, heart, brain, lungs, kidneys, or musculoskeletal system; ③ Patients with a history of or current psychiatric disorders; ④ Patients on long-term glucocorticoid therapy; ⑤ Patients using growth hormone, γ-aminobutyric acid, lysine, inositol, or vitamin B12.
5. Any uncontrolled, clinically significant laboratory abnormalities that, in the opinion of the investigator, may interfere with the interpretation of study data or the subject's ability to participate in the study.
6. Participation in other clinical intervention studies involving drugs, dietary supplements, probiotics, or prebiotics within the past 4 weeks.
7. Subjects with severe infection or severe trauma as determined by the investigator, or those who have undergone moderate to major surgery within the past month.
8. Known allergy to any components of the probiotic product.
9. Subjects deemed unsuitable for participation in this clinical study by the investigator for any other reason.