What is Irritable Bowel Syndrome (IBS)?
IBS is a common functional gastrointestinal disorder that affects 1 in 7 adults. It is characterised by symptoms that are not explained by other disorders such as coeliac disease and inflammatory bowel disease. The symptoms associated with IBS can vary from person to person. This includes the frequency severity and the types or number of symptoms experienced. The most common symptoms of IBS include;
Stomach pain or discomfort
Bloating
Wind
Diarrhoea
Constipation
Nausea
These symptoms can lead to stress and anxiety and affect our quality of life. The exact cause of IBS is not completely understood, however there are numerous factors that are believed to potentially trigger symptoms. The main cause is thought to be enteric nervous system dysfunction. This is the main and most important nervous system in our gastrointestinal tract (GIT). It is often referred to as our “second brain” and plays an important role in regulating the function of our GIT including motility or its movements and the transit of the contents within it. Others include low grade inflammation, gut hypersensitivity, delayed gastric emptying, acute gastroenteritis and lifestyle factors including psychological stress and life events.
How is IBS Diagnosed?
There are currently no medical tests available that can diagnose IBS. Your doctor is likely to take a detailed medical history and complete a physical exam to eliminate whether your symptoms may be caused by another medical condition. Your Dietitian will take a detailed medical, lifestyle and dietary history including the type and severity of symptoms you have been experiencing.
Once other conditions have been ruled out a set of diagnostic criteria called the Rome IV Criteria for Diagnosing IBS will be used to confirm if you have IBS. This includes whether you have been experiencing recurrent abdominal pain, on average, at least 1 day per week in the last 3 months, which is associated with 2 or more of the following;
Related to defecation (may be increased or unchanged by defecation)
Associated with a change in stool frequency
Associated with a change in stool form or appearance
What are IBS Subtypes?
IBS subtypes are determined on how often very loose or very hard stools occur. Percentages are used to assist with determining how frequently different stool types are occurring and are based on stool form on days with at least one irregular bowel movement.
There are three main subtypes of IBS;
IBS-C: constipation predominant
IBS-D: diarrhoea predominant
IBS-M: mixed bowel habits
There is also a fourth IBS subtype, IBS-U: unclassified. This is used when a person meets the diagnostic criteria for IBS, however their bowel habits cannot be accurately categorised into one of the 3 subtypes above.
It is important to remember that IBS subtypes are not separate conditions and that a subtype can be re-classified based on changes to a person’s bowel habits. Symptom quantity, intensity, and severity can also vary from person to person.
How Knowing Your IBS Subtype Can Manage Your IBS Symptoms
Knowing your IBS subtype is important as they each have different clinical signs and symptoms and management strategies vary between the different subtypes. Knowing your IBS subtype means that the management of your IBS can be individually tailored to your meet your specific needs which will assist with improving your symptoms.
Through changes to your diet and lifestyle, the nutritional management of IBS aims to improve your quality of life and decrease the frequency and severity of your symptoms. A dietitian will be able to work with you to develop a personalised management plan to ensure this occurs whilst you are getting all the nutrition you need with a healthy, balanced diet and a wide variety of foods.
The dietary cause of the symptoms associated with IBS is largely due to a group of carbohydrates called FODMAPs (Fermentable, Oligosaccharides, Disaccharides, Monosaccharides, and Polyols). Examples of FODMAPs include fructose, lactose, fructans and sorbitol. These carbohydrates can be poorly absorbed in the bowel, which leads to the symptoms associated with IBS. Did you know that a low FODMAP diet can help improve gut symptoms in up to 75% of people with IBS?
It’s important to remember that FODMAPs are not the cause of IBS, however limiting these in the diet can help control IBS symptoms. Studies also show that those with IBS who follow the low FODMAP diet with the assistance of an Accredited Practising Dietitian can get better relief from their symptoms.
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References
Gandy J & the British Dietetic Association. Manual of Dietetic Practice–Fifth Edition. 2014: 460-466.
Gibson PR, Shepherd SJ (2010). Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach. Journal of Gastroenterology and Hepatology. 25: 252–258.
Longstreth GF, Thompson WG, Chey WD, Houghton LA, Mearin F, Spiller RC (2006). Functional bowel disorders. Gastroenterology. 130: 1480–1491.
National Institute for Health and Care Excellence (NICE) (2008). Irritable bowel syndrome in adults: Diagnosis and management of irritable bowel syndrome in primary care. CG61.
Schmulson MJ & Drossman DA (2017). What Is New in Rome IV. Journal of Neurogastroenterology and Motility. 23:151-163.