SIBO – A complex condition with a simple explanation

SIBO is THE buzzword in the digestive world today. It’s used more and more often amongst those suffering from digestive symptoms yet is not well recognised by the medical community. Do you really understand what it is and whether it affects you?

In this article, I’ll provide you with a simple overview of SIBO and why it gets confused with IBS too. In Part 2 next week, I will discuss the various ways I decide if SIBO is the problem and the different methods to help alleviate the symptoms. 

Prefer to watch or listen to SIBO Part 1? Simply click the links below ↓

Listen or Download the SIBO Part 1 PODCAST

What is SIBO?

SIBO stands for Small Intestinal Bacterial Overgrowth.  Very simply this is gut bacteria in the wrong place. There should be very little bacteria in the small intestines but for some individuals, there is an abnormal overgrowth of the wrong type of bacteria that chooses to reside in the very place where food should be digested and absorbed.

SIBOdiscomfort  – A complex condition with a simple explanation

For those who have SIBO, the symptoms can vary from discomfort to excruciatingly painful. Common symptoms are bloating and distension of the abdomen (from 2 minutes to 3 hours after eating); increased wind; abdominal discomfort and pain; pain under the sternum; burping; nausea; diarrhoea and /or constipation. 

But the symptoms can extend way beyond the obvious gut digestive ones.

These are the signs I also look out for when I “join up the dots” to look for the root cause of digestive symptoms: Iron deficiency anaemia, low B12, acne rosacea and even brain fog. There are even links to several medical conditions too like fibromyalgia and inflammatory bowel disease like Crohn’s…

It’s all about Gut Bacteria

Bacteria are an essential component of the human gut microbiome. There are trillions of microbes that reside in the large (not small) intestines- also known as the colon. In fact, there are ten times the quantity of microbes as there are cells in the body.  It’s a remarkable discovery. And they are most certainly controlling us!


In this blog, I’m not exploring the role of the microbiome but to understand human health and gut symptoms it is really important to appreciate that not all the bacteria (and parasites and yeasts) are good. There are many “bad” strains that can take hold and create all sorts of unwanted symptoms in the human host. 

In SIBO, microbes have built up a residency in your small intestines – the area between the stomach and the colon. This is a very long winding tube where food is digested and most nutrients are absorbed into the bloodstream.

Some microbes have found a way to shift from the colon and into the small intestines. Others have lingered on their journey to the colon and decided to take residence.

Is SIBO the same as IBS?

You may be thinking, “but aren’t these “SIBO” digestive symptoms just IBS”? Well yes and no and this is where it can become confusing. 

Put very simply, SIBO (bacteria in the wrong place) can be a cause of IBS symptoms (hence the overlap between the two). But not everyone with IBS has SIBO. This means that the root cause of IBS symptoms is not due to bacteria residing in the small intestines.

To be honest, I’m less interested in labels like IBS. I like to keep things simple especially for clients. Every client who approaches me saying they have IBS or suspected IBS, I’m most interested in an in-depth understanding of their actual symptoms. 


Because it’s only when I have a very full picture of the symptoms that I can start to work out patterns of digestive insufficiency, microbiome dysbiosis and poor gut barrier function – together with food and lifestyle patterns – and put in place protocols to help clients get relief.

Why do (SIBO) bacteria cause such awful symptoms?

The bacteria that are linked to SIBO are predominantly hydrogen sulphide and methane gas producers. These are not gut species that we want present anywhere in the gut at all. 

Remember that the small intestines are where food is digested? 

These bacteria love to feed off certain carbohydrates and in doing so create gas and a perfect breeding ground for more bacteria to grow. It’s a truly unhealthy gut environment. Hence the typical symptoms of bloating, pain and discomfort and altered bowel movements either diarrhoea or constipation. Even a combination of the two. 

It’s tiresome I know. Uncomfortable. Embarrassing. And quite frankly it can take the joy out of eating and socialising.

How do bacteria end up as SIBO?

We constantly swallow bacteria and pathogens with our food. Sounds horrible I know but it’s a fact. Most pathogens should be killed with the strongly acidic environment of the stomach and the presence of bile. Those that survive should be swept along through the small intestines and down to the colon with strong and regular contractions. This is part of a complex system called the Migrating Motor Complex (MMC).

Too often people end up with very poor motility and movement through the small intestines after food has left the stomach. This allows the bacteria to linger and build up an unwanted presence in the small intestines.

Is this the same as constipation?

There may be a connection or one contributing to the other,  but unfortunately, you cannot assume that the reasons for constipation and slow movement through the colon are the same as slow motility through the small intestines. Unfortunately, it isn’t that simple.

The Good News

Whilst SIBO can be complex, we do now know there are several factors that can lead to slow motility. If we can understand the cause(s) it helps determine the route to resolution.

As part of my in-depth case history taking with clients I will always be looking for signs of chronic stress, use of stomach acid reducing medications, long-term use of other medications, traveller’s diarrhoea, food poisoning, use of antibiotics, abdominal surgery, frequent eating and of course food choices.

In Part 2 – I will explain how to help determine if SIBO is part of the “IBS” problem and the methods I use towards its resolution.

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Again, thanks for reading. 

Keep your eye out for more articles and Peyton Principles in the media.


Caroline is a Professional Nutritionist, Naturopath based in Wiltshire.

A little more about me…

Providing expert, personalised, health advice utilising 10 years of nutritional therapy and naturopathy experience with a strong emphasis on digestion and gut health. Zoom or face to face Consultations.

I also develop and deliver wellbeing in the workplace workshops.

Helping people live happier, healthier more active lives.

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Caroline Peyton

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