What Causes IBS?

One of the most frustrating things about being diagnosed with IBS, is just not understanding how and why you got it. Even though it doesn’t change things, it can be incredibly helpful to at least understand where it came from.

IBS (Irritable Bowel Syndrome) is a type of functional bowel disorder (FBD). FBDs include a whole range of gastrointestinal disorders where the gut is just functioning differently to normal. This shows up in symptoms including stomach pain, bloating and a change in bowel habits. However, IBS is by far the most common and it affects 7-15% of the population worldwide. For more info on exactly what it is and how to find out if you have it check out my previous blog post on just that.

Once you know what it is and you think you’ve got it, the next question is normally ‘WHY’ That’s what we’re going to be talking about today.


Annoyingly, there’s not one, obvious cause, and it’s likely that there are a few different factors at play. Here are the possible factors:



Digestion relies on lots of muscles inside your digestive tract pushing your food through it. Sometimes, there can be a dysfunction in the muscles that do that, causing your gut motility to increase or decrease. This means that the time for food to travel through your colon (large intestine) either accelerates or decelerates. If it accelerates, it’s likely to lead to diarrhea. Whereas, if it decelerates, it’s likely to lead to constipation.



You’ve probably heard this term before. If not, it basically just refers to the connection between the gut and the brain and all the nerves etc that allow them to communicate. What can happen with IBS, is that there is a problem with that connection between the gut and the brain, leaving your brain to feel more pain than it normally would from your gut.



Stress and anxiety can have a huge influence on your gut motility (i.e. increasing or decreasing the time it takes your food to travel through your gut). You’ve probably felt this when you have an exam or other stressful event coming up and you get a bout of diarrhea or constipation. Stress can also affect your pain threshold and impair the barrier functions of the digestive tract. This means food can leak out and interact with your immune system, where it can develop a response (i.e. a symptom).



Your gut micro-biome is kind of like a garden. It’s the collection of bacteria, both good and bad, that live in your gut. If you’ve got too many of the bad ones and not enough of the good, you’re deemed to have an imbalance (sometimes called dysbiosis). An imbalance can lead to all of the frustrating symptoms of IBS.



This is sometimes called post-infectious IBS. If you had some sort of gut infection, or parasite (maybe whilst travelling) before you got IBS, this is likely to be the cause of yours. What happens when you have an infection like this is that the walls of your intestines become more permeable, i.e. they allow food to leak out. This then activates your immune system, which can cause inflammation. This can then remain and cause IBS.



Your doctor most likely won’t be able to tell you what the cause of your IBS is (unless it’s obviously post-infectious IBS). If you find a doctor that can, please let me know! However, it can be helpful to just be aware of what the possible causes are and to look at addressing them or managing the symptoms.

Some of these causes can be addressed directly (e.g. stress/anxiety and an imbalanced gut micro-biome). However, the good news is that, whatever the cause of your IBS, it can be managed. Whatever symptoms you’ve got, there are diet and lifestyle changes that you can make to reduce and manage them.


There isn’t one, obvious, cause of IBS. There are likely to be a few different factors at play. Possible causes are:

  • Changes in gut motility

  • The gut-brain axis

  • Stress + anxiety

  • An imbalanced gut micro-biome

  • Gastroenteritis/parasite infection

The good news is, whatever the cause, there are ways to manage your IBS symptoms through diet and lifestyle tweaks! Get in touch with me if you want to find out more.

I hope you found this useful. Which of the above causes do you think might have affected your IBS? Let me know in the comments below.

Thanks so much for taking the time to read this!

Sophie x

Filed Under: Eating OutGeneralTips & Advice

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