As part of IBS Awareness Month, Registered Nutritionist & Gut Health Specialist Marilia Chamon has explained a rarely discussed type of IBS, as well as her own personal story.

Irritable Bowel Syndrome (IBS) is a functional gut disorder that affects 1 in every 7 people, or 15% of the world population, where 2/3 of treatment seekers are women. IBS is characterised by chronic, relapsing symptoms including lower abdominal pain and discomfort, bloating, wind, and altered bowel habits ranging from diarrhoea to constipation.

Although much has been talked about IBS in recent years, very few health professionals bring to attention the possible causes that underlie its collection of symptoms - when Probio7 invited me to write a piece on IBS, I was thrilled to have the opportunity to share my story and bring to attention that food poisoning is the leading known cause of IBS, accounting for 60-70% of cases of IBS-Diarrhoea type.

Have you heard about Post-Infectious IBS?

Post-Infectious IBS is a form of IBS that is caused by food poisoning. Although not much is talked about, 1 in every 9 people who experience food poisoning happen to develop Post-Infectious IBS up to six months after the initial bacterial infection. Post-infectious IBS almost always has a diarrhoeal component, a hallmark symptom of traveller’s diarrhoea and gastroenteritis.

But how can food poisoning lead to development of IBS?

The most common bacteria that cause food poisoning - Salmonella, E.Coli, Campylobacter and Shigella, release a toxin called Cytolethal Distending Toxin B (CdtB). When CdtB enters the body, the immune system fights back with an antibody called anti-CdtB. Due to molecular similarities, CdtB can look similar to vinculin, a naturally occurring protein in the body that is critical for a healthy gut function. Because of this similarity, the immune system gets confused and thinks it needs to fight back against vinculin and starts to produce another antibody, called anti-vinculin. This consequently leads to an autoimmune response where the body starts to attack itself.

The production of anti-vinculin antibodies leads to gut nerve damage and improper functioning of the Interstitial Cells of Cajal (ICC) and the Migrating Motor Complex (MMC), and both play a critical role in gut motility and proper gut function. When gut motility is impaired, the gut microbiome is consequently disrupted leading to all sorts of digestive symptoms such as bloating and alternating bowel movements. Another consequence of a disrupted gut microbiome is increased visceral hypersensitivity - a hallmark of IBS symptoms - which alters the gut-brain axis communication and increases brain response to abdominal pain.

How is Post-Infectious IBS diagnosed?

Until recently IBS was a diagnosis of exclusion, meaning that GPs and medical specialists would rule out any medical condition such as Inflammatory Bowel Disease, Coeliac Disease and most recently

Endometriosis, before concluding your digestive symptoms are caused by IBS.

It is of course of extreme importance to go through this process to make sure nothing more serious is going on, and if you get cleared from any medical condition and think your digestive symptoms started after an episode of food poisoning/gastroenteritis, you are a strong candidate to have developed Post-Infectious IBS.

Post-infectious IBS is the only form of IBS that has a diagnosis test called IBS Smart - a blood test developed in the USA by world leading IBS researcher Dr. Mark Pimentel, that measures the levels of two validated IBS biomarkers, anti-CdtB and anti-vinculin, providing a positive or negative result. If the measured  biomarkers are elevated, it is then confirmed that your IBS developed from food poisoning/gastroenteritis.

At the moment only a licensed practitioner can order IBS Smart but hopefully it will soon become available.

My story

You must be wondering why I am here sharing detailed information about a condition that is hardly ever spoken about and promoting a test I have no affiliation with. To put things into context, I decided to specialise in gut health after spending nearly a decade struggling with daily digestive symptoms. Like most of my clients, I ran every medical test under the sun and by a diagnosis of exclusion, was told my chronic symptoms were due to stress and anxiety.

Back then I had a hard time accepting the diagnosis because for most of my life I had not had a single digestive problem, until an episode of food poisoning that changed all that.

It was clear to me the food poisoning event was the initial trigger to my digestive symptoms and despite mentioning it to every medical doctor, that was never taken into consideration. That sparked an immense interest in gut and digestive health and led me to take a deep dive into the IBS universe, bringing me to qualify as a nutritional therapist and specialise in gut health and IBS.

Symptom management

Food poisoning is just one of the many causes that lead to the development of IBS, it is widely known that stress and anxiety are some of the main triggers for most individuals. Regardless of what triggers your IBS symptoms, a multifactorial approach is needed to keep them at bay while working on the underlying cause(s) of why you experience them in the first place.

There is growing scientific evidence that suggests an alteration in the diversity and composition of the gut microbiome plays a fundamental role in the development of IBS. IBS sufferers tend to have a lower percentage of beneficial bacteria such as Lactobacillus and Bifidobacteria. This alteration in the diversity of gut bacteria has been linked to symptoms like visceral hypersensitivity, anxiety and depression, and they also seem to impact the communication between the gut and the brain resulting in alterations in brain response towards abdominal distention (bloating). This is particularly relevant to those that developed IBS as a result of food poisoning and restoring gut bacteria balance is an essential part of my work when working with IBS clients.

Because of altered communication between the gut and the brain, individuals that suffer with IBS have an abnormal response to the fermentation of specific carbohydrates called FODMAPs. Fermentation is a normal process of digestion and happens when beneficial gut bacteria break down dietary fibre. For that reason the low FODMAP diet is usually the starting point for symptom management as it decreases the amount of fermentable carbohydrates for a limited time. The low FODMAP diet involves 3-steps and should be done with the guidance of a FODMAP trained nutritionist or dietitian otherwise it can become restrictive and difficult to implement.

Yoga, meditation and gut-directed hypnotherapy have also shown to be effective in rewiring the gut-brain communication and are a good alternative for those who do not respond well to the low FODMAP diet and have their symptoms triggered by stress and anxiety.

In addition, supplements such as probiotics and peppermint oil capsules can also be helpful. For probiotics to be effective, it is important to look at strains that have been clinically researched such as the collection of strains i3.1.


IBS can be a tricky and debilitating condition to navigate - it can affect many aspects of life such as work, social events and relationships as well as self-confidence. One study with nearly 2,000 IBS sufferers found that they would be willing to give up 25 percent of their remaining lifespan to be symptom free - that reinforces how debilitating this condition can be. My number one advice to anyone living with IBS is to look for a qualified gut specialist as there is so much that can be done to improve symptoms and quality of life - a specialist would also be able to check if your IBS is not being caused by any other gut condition such as Small Intestinal Bacterial Overgrowth, or SIBO - a completely different topic that I will leave for another post!

If you would like to book a free 1:1 consultation with our inhouse nutrition team to discuss your gut health, simply click here.