IBS vs SIBO: What’s the Difference?
Bloating, abdominal discomfort, constipation, diarrhoea and food sensitivities can all leave you wondering what’s actually going on with your gut.
Two terms that often come up when investigating ongoing digestive symptoms are IBS and SIBO. While they can look very similar on the surface, they aren’t the same thing, and symptoms alone don’t always tell us the whole story.
At Thryve Naturopathy, we take a personalised, testing-led approach to digestive health. Rather than assuming that bloating = SIBO or irregular bowel movements = IBS, we look at your complete health picture and, where clinically appropriate, use functional pathology testing to investigate what may be contributing to your symptoms.
So, IBS vs SIBO: what’s the difference, and how can we investigate what’s actually happening in your gut?
What is IBS?
Irritable Bowel Syndrome (IBS) is a common gastrointestinal disorder characterised by recurring abdominal pain alongside changes in bowel habits.
Depending on the individual, IBS may predominantly involve constipation (IBS-C), diarrhoea (IBS-D), or a combination of both (IBS-M).
Common IBS symptoms include:
Bloating and abdominal distension
Abdominal pain or cramping
Constipation or diarrhoea
Alternating bowel habits
Excessive gas
Urgency
Feeling as though you haven’t completely emptied your bowels
IBS is considered a disorder of gut-brain interaction, and there can be multiple factors influencing symptoms, including gut motility, visceral sensitivity, diet, stress, previous gastrointestinal infections and changes within the gut microbiome.
This is why I don’t believe in treating an IBS diagnosis alone.
Two people can have the same diagnosis and similar symptoms, while the factors contributing to those symptoms may be completely different.
What is SIBO?
Small Intestinal Bacterial Overgrowth (SIBO) occurs when there is an excessive number of bacteria within the small intestine.
Most of our gut bacteria are naturally concentrated within the large intestine. When excessive bacteria are present within the small intestine, increased fermentation can occur, contributing to digestive symptoms.
Common SIBO symptoms include:
Significant bloating, particularly after eating
Excessive gas
Abdominal discomfort
Constipation or diarrhoea
Changes in bowel habits
Food intolerances or sensitivities
In some cases, SIBO can also interfere with normal digestion and nutrient absorption.
IBS vs SIBO: Why Symptoms Don’t Tell the Whole Story
This is where digestive health can become a little more complex.
IBS describes a pattern of digestive symptoms, whereas SIBO refers to bacterial overgrowth within the small intestine.
But bloating doesn’t automatically mean SIBO. Constipation isn’t always IBS. And digestive discomfort doesn’t necessarily mean there’s something wrong with your microbiome.
Similar symptoms can have very different contributing factors.
Rather than focusing solely on the symptom, I prefer to ask:
Why might this be happening for this person?
Your health history, diet, bowel habits, medications, previous infections, stress, nutrient status and other symptoms can all provide important clues.
And sometimes, functional pathology testing can help us look a little deeper.
Looking Deeper: Functional Pathology Testing
When it comes to gut health, functional pathology testing can provide additional information about what may be happening within the digestive environment.
The type of testing recommended depends entirely on the individual. Not everyone with digestive symptoms needs testing, and more testing isn’t necessarily better.
The aim is to choose a test when the results are likely to provide useful information and help guide the direction of treatment.
One test I may consider for clients experiencing persistent or complex digestive symptoms is Complete Microbiome Mapping.
What Can Complete Microbiome Mapping Show?
Complete Microbiome Mapping is a comprehensive stool analysis that provides information about the gastrointestinal microbiome and digestive environment.
Rather than simply telling us whether you have “good” or “bad” gut bacteria, it can provide a much broader picture of what’s happening within the gut.
Depending on the test used, we may be able to assess:
The abundance of particular commensal bacteria
Potentially pathogenic or opportunistic microorganisms
Markers associated with intestinal inflammation
Digestive and pancreatic function
Markers of intestinal immune activity
The presence of certain parasites
Yeasts and other microorganisms
Other markers relating to gastrointestinal health and function
The important part isn’t simply finding something outside a reference range.
It’s understanding whether that finding is relevant to your symptoms, health history and overall clinical picture.
For example, two people may both present with bloating, constipation and abdominal discomfort, but their test results and contributing factors could look very different.
That’s why I don’t love generic “gut protocols”.
Your treatment should be based on your presentation, not simply the symptom written at the top of your case notes.
Does Complete Microbiome Mapping Test for SIBO?
This is an important distinction.
SIBO occurs within the small intestine, whereas Complete Microbiome Mapping primarily provides information about microorganisms and other markers detected within a stool sample.
For this reason, stool microbiome testing isn’t used on its own to diagnose SIBO.
If SIBO is suspected based on your symptoms and clinical history, SIBO breath testing may be considered instead. Breath testing measures gases produced by microorganisms following consumption of a specific test substrate.
The goal isn’t to order every gut test available.
It’s to determine which test, if any, is appropriate for the question we’re trying to answer.
How Can a Naturopath Help With IBS and SIBO?
When you work with a naturopath for digestive issues, the first step should be understanding the bigger picture.
At Thryve Naturopathy, we begin with a comprehensive assessment of your health, including your digestive symptoms, bowel habits, diet, previous gastrointestinal infections, medication and antibiotic history, stress, nutrient status and broader health history.
From there, we can decide whether further investigation may be useful.
This could include reviewing conventional blood pathology or, where clinically appropriate, considering functional pathology testing such as Complete Microbiome Mapping or SIBO breath testing.
Your treatment plan is then personalised to your findings and may include nutrition, herbal medicine, targeted nutritional supplementation and practical lifestyle strategies.
Testing is only useful if it changes what we do with the information.
What Can You Do to Support Your Gut Now?
While persistent digestive symptoms may warrant further investigation, there are some simple foundations that can support healthy digestion regardless of whether you have IBS or SIBO.
Start with the basics:
Slow down at meals. Take the time to sit, chew your food properly and eat without rushing where possible. Digestion begins before food reaches your stomach.
Support regular bowel movements. Adequate fluid, fibre and daily movement can all play a role in healthy bowel function.
Include variety in your diet. A diverse, plant-rich diet can help support a diverse gut microbiome—although individual tolerance matters, particularly when digestive symptoms are present.
Pay attention to patterns, rather than individual foods. Keeping a simple symptom and food diary for a week or two can help identify patterns between meals, bowel habits, stress and symptoms.
Be cautious with unnecessary restriction. Continually removing foods without understanding why they're causing symptoms can leave you with an increasingly limited diet without addressing the underlying issue.
And perhaps most importantly, if something repeatedly causes symptoms, get curious about why rather than simply cutting it out.
Sometimes the symptom is the clue, not the problem itself.
Do You Need Gut Testing?
Not necessarily.
Sometimes your symptoms and health history give us enough information to know where to begin.
Other times, you may have been experiencing symptoms for years, tried multiple approaches without lasting improvement, or simply feel like you still don’t understand why your gut is behaving the way it is.
That’s where further investigation may help us fill in some of the missing pieces.
At Thryve Naturopathy, testing is used purposefully—not routinely.
If you’re regularly experiencing bloating, constipation, diarrhoea, abdominal discomfort or unpredictable bowel habits, you don’t have to simply accept them as your normal.
Understanding what may be contributing to your symptoms is the first step towards knowing how best to support your gut.
Test where appropriate. Understand the whole picture. Treat the individual.
If you’re ready to better understand what’s happening with your gut, I’d love to work with you.
Ready to Better Understand Your Gut?
If you’ve been living with persistent bloating, IBS symptoms or unpredictable digestion and feel like you’re still missing answers, we can take a closer look.
At Thryve Naturopathy, we’ll explore your symptoms, health history and potential contributing factors, with functional pathology testing considered where appropriate.
Ready to understand what’s happening beneath the surface? Book a consultation with Thryve Naturopathy.