Traveling Family walking through airport

Bacteria are responsible for many of our digestive processes. These bacteria, known collectively as the gut microbiome, include trillions of individual bacteria from thousands of species. Traveling extended distances, such as those during vacationing, often cause disruptions in normal digestive cycles. Avoiding such issues as Traveler’s Diarrhea and constipation might be as simple as learning a bit more about your own microbiome!


The human digestive tract is full of mysterious. Modern research shows a deep connection between bacteria, digestion, and overall human health. In general, Science regards the human microbiome to be comprised of two major bacterial Phyla: Bacteriodetes and Firmicutes (R). Within these two groups, there is an immense number of different types of bacteria to consider.

For those interested, uBiome is a company that provides in-home [poop] tests that will provide a report of one’s digestive bacteria. These tests are surprisingly affordable.

Among the many phenomena of human health that perplex modern science, the role of bacteria in our bodies is one of the most prominent. It’s clear that these bacteria play an integral role in helping utilize and synthesize dietary nutrients, regulate hormones, and influence digestive cycles. Understanding more about the intricacies of the microbiome can help address many digestive issues such as traveler’s diarrhea and indigestion.

suitcase containing only shoes and toilet paper

What is Traveler’s Diarrhea?

Traveler’s Diarrhea is a term used to describe any number of digestive disturbances experienced during travel that result in diarrhea. The CDC reports this as the single most common travel-related illness and notes that steps to regulate and control bacterial shifts in the human body, such as the administration of antibiotics, may treat the issue.

As many as 50% of people traveling to developing countries experience at least one episode of diarrhea (R). This might sound trivial at first glance, but in a small percentage of cases (5-10%) these symptoms can progress to be more like dysentery which includes fever, chills, and blood in the stool. All around; not a good time.

What Causes Traveler’s Diarrhea?

Presumably, many of the cases of traveler’s diarrhea are caused by the exposure to foreign bacteria. That’s foreign in the sense that one’s body isn’t already used to it, not necessarily that it’s from a different country. The highest incidence rates of traveler’s diarrhea are in South-Central and West Asia (R).

Existing research on the subject considers traveling a multi-day experience, not just taking the “long way” to work. For example, driving to Cincinnati from Sacramento would constitute a considerable amount of multi-day travel. On the other hand, driving over to San Francisco for the weekend might not.

To be honest: there isn’t enough research available to even guess at what might constitute enough distance to have an effect, in and of itself, on the human microbiome (R). On the other hand, if your traveler’s diarrhea is caused by exposure to foreign bacteria it wouldn’t be a matter of distance-traveled at all—just the exposure.

illustration of gut microbiome bacteria

Possible Microbiome Connections

Understanding a bit about how the microbiome is affected explains its role in the development and progression of traveler’s diarrhea. For example, traveling is often noted as causing a disruption in one’s natural circadian rhythms. This is the basis of how Jetlag develops.

Circadian Rhythm Disruptions

Animal tests have shown that such disruptions in the circadian cycle can cause detrimental shifts in the microbiome. One such test found there to be a significant increase in bacteria that cause leaky gut syndrome(R).

The human circadian rhythm is primarily regulated from processes centered in the hypothalamus region of the brain. This region receives direct feedback from the optical nerve in response to changes in light. As the day grows darker, our bodies are signaled to prepare for sleep. There are other areas in our body, referred to as periphreal clocks that can influence overall circadian rythmns as well.

One such clock (if not more) is located in our digestive tracts. Any disturbance in the microbiome is likely to have an influence over the periphreal circadian system which, in turn, could disrupt one’s overall sleep/wake cycle (R).

Being Off-Schedule

One study compared shifts in the microbiome of two individuals over the course of a year. While narrow in participation, this study boasted more than 10,000 specific assessments of bacterial states. For the most part, the microbiome of each individual was unchanging. Upon traveling from the United States to a developing country, one host saw a two-fold increase in their Bacteriodetes:Firmicutes ratio. This is a very significant change. What’s remarkable is that the shift reversed itself after their return to the US (R).

The abrupt shift in bacteria ratios without bacterial infection is a curious case to consider. This hints that other factors than exposure to foreign bacteria can cause shifts in our microbiome composition. One supporting notion is that changes in diet, such as in increased consumption of amino acids, can cause an increase in bacteroidetes‘ species (R).

The bottom line here is that just getting off your daily schedule—be it eating different foods, waking at different times, getting more or less exercise—may all influence the composition of your microbiome. Taking action to mimic one’s daily routine as best as possible in the first few days of travel could help reduce the risk of Traveler’s Diarrhea. One example: if you normally lift weights and find yourself without a gym, do some pushups during the time you’d normally be working out.

woman holding probiotic supplement capsule in hand

Supplements for Traveler’s Diarrhea

Doing push-ups, jogging, or doing an improvised Yoga routine aren’t always convenient (or possible) during travel. For such cases, at least when one is trying to reduce the risk of traveler’s diarrhea as much as possible, dietary supplements can help.


Prebiotics are a fancy name for fiber supplements. Good-‘ol Metamucil for most of us here. Today, there are many dietary fiber supplements labeled specifically as prebiotic (relevant to probiotics) which directions indicating to take them before meals and any probiotic supplements.

The idea is that prebiotics can help probiotic bacteria thrive. These compounds, often referred to as soluble dietary fibers, sort of “reinforce” the microbiome. Taking prebiotics may help make your microbiome less-susceptible to changes during travel that result in traveler’s diarrhea. Researchers have demonstrated that prebiotics can help stabilize bacteria following diets meant to cause dramatic shifts (R).


Just like prebiotics help reinforce existing gut bacteria balances, so too can adding more bacteria! Makes enough sense, right? To help illustrate just how influential probiotics can be, let’s consider a 2007 study published in journal Travel Medicine and Infectious Disease.

Among 940 cases examined, researchers found that the probiotic bacteria Saccharomyces Boulardii, Lactobaciluus acidophillus, and Bifidobacterium bifidum significantly-reduced the incidence rate of traveler’s diarrhea. In other words, take your probiotics when traveling if you want to stay out of the bathroom!

Final Thoughts

Microbiome composition is one of the most diverse facets of all aspects of human health that can be considered as being overly individualistic. It’s likely that no two human microbiomes have ever been identical. Traveler’s Diarrhea is simply one case in which we recognize gut bacteria as having significant influence. Research suggests staying on routine as much as possible and taking supplements like probiotics and prebiotics can help reduce the risk of traveler’s diarrhea significantly.

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