Journeying along the historic Silk Road exposes travelers to dramatic dietary shifts, unfamiliar microbial environments, and the physical stresses of long-distance travel-all known to disrupt gut health and cause gastrointestinal complaints, including traveler's diarrhea and sleep disturbances. Such disruptions may also elevate the risk of acquiring antibiotic-resistant organisms.

This randomized, double-blind, placebo-controlled trial evaluated whether probiotic supplementation can help maintain gut microbial balance and support traveler well-being during trips to Silk Road regions. In addition to monitoring changes in gut microbiota composition, the study assessed gastrointestinal symptoms, sleep quality, anxiety levels, overall well-being, gut immune markers, functional profiles of the microbiome, and the presence of antibiotic resistance genes.

Journeys along the Silk Road-with their unique dietary shifts, unfamiliar water and food sources, novel microbial exposures, altered sleep patterns, and psychological adjustments-can significantly disrupt gut microbiota and impact overall health. Prior research has shown that even short-term travel can lead to substantial fluctuations in gut microbial composition, often accompanied by gastrointestinal symptoms and reduced well-being, underscoring the need for effective strategies to support gut homeostasis during such journeys.

Gastrointestinal distress, including traveler's diarrhea and non-diarrheal symptoms such as abdominal pain and irregular bowel movements, remains a common challenge. These issues can considerably diminish the travel experience. Furthermore, travel has been linked to an elevated risk of acquiring antimicrobial resistance genes, with the gut serving as a potential site for the exchange and amplification of resistant organisms.

Sleep disruptions-stemming from changes in routine and environment-also play an important role in traveler well-being. The gut-brain axis provides a mechanism through which sleep quality may influence gastrointestinal vulnerability, highlighting the interconnected nature of these systems.

Probiotics represent a promising intervention to support travelers. These beneficial microorganisms may enhance gut barrier function, modulate immune activity, inhibit pathogens, and produce metabolites that contribute to both gut and systemic health. Although some studies suggest probiotics can alleviate gastrointestinal symptoms and reduce the risk of diarrhea, robust evidence specific to the Silk Road travel context remains limited.

In this randomized, double-blind, placebo-controlled trial, effects of daily probiotic supplementation on gut microbiota stability, gastrointestinal symptoms, sleep quality, anxiety, and overall well-being in adults traveling the Silk Road will be evaluated. Immune markers, microbial functional pathways, and antibiotic resistance gene profiles will be identified to better understand the potential mechanisms of action. The investigators hypothesized that probiotic intake would help maintain microbial balance, reduce travel-related symptoms, and support physical and emotional well-being throughout the journey.

Inclusion Criteria:

• Generally healthy adults
• Scheduled to undertake a short-term round trip (less than 7 days) to abroad
• Able to complete study procedures
• Willing to take intervention products

Exclusion Criteria:

• Use of antibiotics, probiotics, hormones, immunosuppressants, biologics or JAK inhibitors within four weeks prior to study
• Chronic or severe systemic diseases (including cardiovascular, hepatic, renal, malignant or psychiatric disorders)
• Uncontrolled parasitic infections
• Long-term use of corticosteroids, growth hormone, vitamin B12, lysine or inositol
• Major surgery within one month
• Allergy to probiotic components
• Other conditions deemed inappropriate by investigators