Researchers in China conducted a randomized, double-blind, placebo-controlled trial to investigate whether a multi-strain Bifidobacterium probiotic could prevent travel-related gut microbiota disruptions.
“Probiotics may serve as an accessible strategy to support well-being under transient environmental and lifestyle stress,” they wrote in the journal Frontiers in Nutrition.
How international travel disrupts the microbiome
International travel can disrupt the microbiome as a result of diet, environment, water exposure and circadian rhythm changes. This can cause transient dysbiosis and gastrointestinal discomfort and may also affect immune, metabolic and psychological states.
Some probiotics can support immunity, reduce inflammation and inhibit pathogens, and Bifidobacterium species are particularly relevant during travel because they aid carbohydrate fermentation, vitamin production, gut barrier integrity, immune modulation and resistance to invading microbes.
Clinical studies have found that probiotics improve bowel regularity, enhance immune responses, modestly reduce traveler’s diarrhea risk and support psychological well-being via the gut–brain axis.
Yet despite extensive probiotic research, few randomized controlled trials have tested whether targeted probiotics can maintain gut microbiota stability and host well-being during short-term international travel, the researchers of the new study noted.
B. infantis M-63, B. breve M-16V and B. longum BB536 support gut stability during travel
The study recruited 40 healthy adults between the ages of 18 and 65 who planned a standardized five-day round trip to Japan. Participants received either a multi-strain Bifidobacterium probiotic, delivering a total of 1.5 × 10⁹ CFU per day from three strains, or a matching placebo containing no live bacteria. The probiotic blend included Bifidobacterium longum subsp.infantis M-63, B. breve M-16V and B. longum BB536.
Validated questionnaires assessed sleep quality, anxiety and overall well-being, and participants recorded daily gastrointestinal and respiratory symptoms before, during and after travel. They also provided stool samples before and after travel, which the researchers analyzed using metagenomic sequencing.
Results indicated the probiotics significantly reduced sore throat and fatigue, as well as improved bowel stability, with the probiotic group noting more normal stools and fewer loose stools compared with the placebo. The probiotic group reported longer sleep, improved stress control and emotional balance, and overall higher well-being than the placebo group, including feelings of energy and waking refreshed.
Gut microbial diversity remained stable in the probiotic group but increased in the placebo group, suggesting that the probiotics helped prevent travel-related microbial disruption. The probiotics also increased beneficial Bifidobacterium and limited the growth of inflammation-associated bacteria seen in the placebo group.
Furthermore, fecal IgA levels dropped after travel in the placebo group but remained stable in the probiotic group, indicating preserved gut immune protection with probiotics, the researchers noted.
Finally, the probiotics reduced travel-related increases in antibiotic resistance genes and appeared to enhance gut metabolic capacity, including energy, nutrient, antioxidant and vitamin pathways. More vitamin-producing pathways were increased in the probiotic group than in the placebo.
“Short-term Bifidobacterium supplementation preserves gut microbiota stability, supports mucosal immunity and promotes physical and psychological well-being during international travel,” the researchers wrote.
“Participants receiving probiotics experienced reduced respiratory and systemic symptoms, better stool consistency, longer sleep duration, lower anxiety and enhanced subjective well-being.”
Regarding mechanisms of action, the study linked benefits to sustained Bifidobacterium abundance, activation of vitamin biosynthesis pathways, maintenance of sIgA-mediated immunity and suppression of antibiotic resistance genes.
It also highlighted that findings support the integral role of the gut microbiome in adapting to environmental change and probiotic use as an accessible approach to enhance resilience during short-term stress.
Source: Frontiers in Nutrition. doi: 10.3389/fnut.2026.1724829. “Bifidobacterium supplementation maintains gut microbiota stability and enhances well-being during short-term travel”. Authors: L. Wang et al.
