30-Second Summary
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Your gut microbiome is the enormous community of microorganisms living in your digestive system.
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It plays an important role in digestion, immune function and overall gut health.
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Everyone's microbiome is different, which is one reason our digestive systems don't all respond to food, illness and travel in exactly the same way.
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Travel can temporarily change your gut microbiome through different foods, environments, routines, illness and medications.
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Probiotics and prebiotics do different jobs: probiotics provide beneficial microorganisms, while prebiotics help nourish beneficial microorganisms already living in your gut.
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You can't make your gut "bulletproof" before travelling, but looking after and preparing your gut before, during and after travel makes sense.
Quick Answer
What is the gut microbiome?
The gut microbiome is the community of trillions of microorganisms—including bacteria, yeasts and other microbes—that live primarily in your intestines. Far from simply being passengers, many interact with your body and play important roles in digestion, nutrient metabolism, immune function and maintaining a healthy intestinal environment.
Why This Matters
Here's something rather extraordinary.
Every time you get on a plane, you're taking trillions of tiny travelling companions with you.
They're already living inside your digestive system, forming an incredibly complex ecosystem known as your gut microbiome.
And just like you, that ecosystem notices when things change.
Different food.
Different water.
Different meal times.
Less sleep.
More alcohol.
New environments.
And potentially exposure to microorganisms your body doesn't normally encounter.
That's where the gut microbiome becomes particularly interesting for travellers.
1. Your Gut Is an Ecosystem, Not Just a Digestive System
For years, we tended to think of bacteria as something to get rid of.
Wash your hands.
Cook your food properly.
Don't drink contaminated water.
All excellent advice—particularly when travelling.
But not all microorganisms are harmful.
Your digestive system is home to an enormous and diverse community of bacteria, yeasts and other microbes. Some are beneficial, some are relatively harmless, and others may have the potential to cause problems under certain circumstances.
What matters isn't simply having "good bacteria" and avoiding "bad bacteria".
It's the community they form and the way they interact with each other—and with you.
💡 Did You Know?
No two people's gut microbiomes are exactly the same.
Your microbiome is influenced by factors including your diet, age, environment, lifestyle and medications.
2. What Is Your Microbiome Actually Doing?
Quite a lot.
The microorganisms living in your gut help perform a surprisingly broad range of functions.
They can help:
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Break down components of food your body can't completely digest on its own
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Produce certain useful compounds
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Interact with your immune system
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Support the intestinal environment
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Maintain normal digestive function
Research into the gut microbiome is developing rapidly, and scientists are still discovering just how complex its relationship with the human body really is.
But one thing has become increasingly clear:
Gut health is about much more than simply whether your stomach feels good today.
3. What Happens to Your Gut Microbiome When You Travel?
This is where it gets particularly relevant.
Think about how dramatically your routine can change within 24 hours of arriving somewhere new.
You may suddenly be eating completely different foods, drinking different water, sleeping at different times, consuming more alcohol, dealing with jet lag and being exposed to microorganisms you've never encountered before.
International travel has been shown to alter the composition of the gut microbiome, although the degree and nature of those changes vary between people and destinations.
For many travellers, changes may be temporary.
But it helps explain why your digestive system can sometimes feel distinctly different when you're away—even when you're not actually sick.
4. "We All Ate the Same Thing. Why Am I the Only One Who's Sick?"
It's one of travel's great mysteries.
Four people eat dinner together.
Three are sightseeing the following morning.
One isn't leaving the hotel bathroom.
Why?
There isn't one simple answer.
Your risk of travellers' diarrhoea can depend on:
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What microorganism you were exposed to
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How much of it you encountered
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Food and water hygiene
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Your individual immune response
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Your existing gut microbiome
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Medications
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Your general health
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And sometimes, plain bad luck
Your microbiome is one part of that picture—not a force field against travellers' diarrhoea.
But it does help explain why two people exposed to apparently similar circumstances don't necessarily respond in exactly the same way.
5. Where Do Probiotics and Prebiotics Come In?
This is where several of our previous articles start fitting together.
A probiotic provides beneficial microorganisms.
A prebiotic provides nourishment that can be used by beneficial microorganisms already living in your gut.
Different jobs.
Potentially complementary roles.
That's why, when developing The Belly Solution's Probiotic + Prebiotic + Electrolyte Rehydration Formula, we chose to include both.
Our probiotic is Saccharomyces cerevisiae var. boulardii, while our prebiotic is Sunfiber® PHGG.
Understanding the microbiome makes it much easier to understand why probiotics and prebiotics aren't interchangeable—and why simply seeing the word "probiotic" on a packet doesn't tell you the whole story.
6. Can You Prepare Your Gut Before You Travel?
You can't make your gut invincible before a holiday.
And no food, supplement or routine can guarantee that you won't develop travellers' diarrhoea.
But looking after your digestive health before you leave is still sensible.
That means eating a varied diet containing fibre, staying hydrated, getting adequate sleep, avoiding unnecessary antibiotics and being sensible about food, water and hand hygiene while you're away.
And if you choose to take a probiotic or prebiotic, understand what you're taking, why you're taking it and the evidence behind it.
The goal isn't to create a mythical "bulletproof gut".
It's to look after and best prepare the one you've already got.
Frequently Asked Questions
Is the gut microbiome the same as gut flora?
They're closely related terms. "Gut flora" is an older expression commonly used to describe the microorganisms living in the digestive tract. Gut microbiome is the more widely used scientific term today and encompasses the broader microbial community and its genetic material.
Is everyone's gut microbiome different?
Yes. While humans share many types of gut microorganisms, the precise composition of the microbiome varies considerably between individuals.
Can travel change your gut microbiome?
Yes. Research suggests international travel can temporarily alter the gut microbiome through changes in diet, environment, routine and exposure to different microorganisms.
Can a healthy gut microbiome prevent travellers' diarrhoea?
Not necessarily. A healthy gut microbiome can't guarantee that you won't develop travellers' diarrhoea. Infection risk depends on many factors, including exposure to infectious organisms, food and water hygiene and individual susceptibility.
However, that doesn't mean your gut health should be ignored. Taking sensible precautionary measures to support and strengthen your gut defences before and during travel may help better prepare your digestive system for the changes and challenges that come with travelling.
Think of it as preparation rather than a guarantee of protection.
What's the difference between a probiotic and a prebiotic?
A probiotic provides beneficial microorganisms, while a prebiotic provides nourishment for beneficial microorganisms already living in your gut.
They perform different but potentially complementary roles.
Should I take a probiotic before travelling?
That depends on the probiotic, the strain and the reason you're taking it.
Not all probiotics are the same, which is why it's important to look beyond the word "probiotic" and understand the specific strain, dose and evidence behind the product you're considering.
Evidence Snapshot
Last reviewed: August 2026
Prepared using:
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Peer-reviewed scientific literature relating to the human gut microbiome
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Research examining changes to the gut microbiome during international travel
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Published research relating to probiotics, prebiotics and digestive health
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Australian consumer health information
This article is intended for educational purposes and will be reviewed periodically as scientific understanding of the gut microbiome continues to evolve.
The Bottom Line
Your gut microbiome isn't something you suddenly acquire when you start taking a probiotic.
It's already there.
It's a complex ecosystem of trillions of microorganisms that travels everywhere you do.
Different foods, environments, routines, illness and medications can all influence that ecosystem.
You can't make your gut immune to travellers' diarrhoea—but that doesn't mean you can't take sensible steps to support, strengthen and prepare your gut defences before you travel.
Understanding your microbiome, and looking after your digestive health before, during and after your trip, can help you make better-informed decisions about your gut health wherever you're going.
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