What is Irritable Bowel Syndrome (IBS)?

What Is Irritable Bowel Syndrome?

Irritable bowel syndrome, otherwise known as IBS, is a common gastrointestinal disorder that is expected to affect around 1 in 5 Australians.

IBS is characterised by recurrent abdominal pain, bloating, gas, cramping, constipation and/ or diarrhea, and mucus present in the stools. IBS presents itself differently in different individuals. This means that the number, frequency, severity, and type of symptoms a person will experience may vary between individuals. Individual IBS symptoms may also vary in severity, duration, and may come and go. Symptoms may last for hours, days, weeks, or months. The symptoms of IBS may be chronic for some individuals, however may disappear in others. 

The Most Common IBS Symptoms Include:

  • Abdominal pain or cramping- this may be relieved by passing wind or a bowel movement
  • Altered bowel motions- including diarrhea, constipation, or alternating between both
  • A feeling of incomplete emptying of your bowel or sudden urgency
  • Bowel movements that contain mucus
  • A feeling of fullness or bloating of the abdomen- this can be due to wind or an increased water volume related to water being drawn into the gut by particular fibres and sugars.

IBS is a functional disorder and does not cause inflammation of the gut, unlike Inflammatory bowel disease (IBD). Since IBS is a functional disorder, it means that the “normal” sensation and function (motility) of the small and large intestines are disturbed. 

IBS is also sometimes referred to as a gut-brain disorder due to evidence showing that gut-related activity is regulated by the brain.

What Causes Irritable Bowel Syndrome?

There is still quite limited evidence around what causes IBS however it is thought that it may be due to a combination of factors such as genetics, stress, psychological, food sensitivities, or a bacterial imbalance in the gastrointestinal tract.

IBS may occur at any age and for most people with this condition, it appears that the bowel is over-sensitive. 

Below are some of the factors that are thought to play a role in IBS:


  • FOOD
    There is currently no clear evidence around food intolerances and IBS, however many people suffer symptoms after eating certain foods. For some people, these triggers may be too much fibre, fat, spice, however, for other people, the trigger may be harder to identify. The best way to determine what an individual may be sensitive to is via the process of dietary elimination and reintroduction using food challenges. Depending on the individual’s symptoms a type of low FODMAP diet may be utilised under guidance by your dietitian. By undertaking a food elimination/ reintroduction protocol with your dietitian, you should be able to determine which foods trigger symptoms as well as your tolerance to these different foods. 
    Some individuals contain insufficient enzymes to digest, absorb, or tolerate some foods. Some individuals are born with this or may develop this as they age. For example, individuals who are lactose intolerant. Some individuals may also benefit from supplementing with enzymes that are needed for the breakdown of fat, protein, and carbohydrates. If this is something you think you are suffering from, please seek medical advice for an appropriate diagnosis to be made.
    It is common that people who suffer from IBS notice that their symptoms worsen or are more frequent when they are suffering from increased stress or anxiety. Strong emotions such as stress can affect the nerves in our digestive system in susceptible people. Chronic stress also has the potential to divert blood supply away from the digestive system due to activating the sympathetic nervous system and therefore resulting in slowed digestion.
    Research shows that women are twice as likely to have IBS and researchers believe that hormonal changes may exacerbate symptoms with women noticing worsening symptoms around their menstrual cycle.
    Certain medications and supplements may cause gut irritation and lead to constipation or diarrhea for example antibiotics, antacids, painkillers, and iron supplements.
    There are a few other factors which may result in symptoms of IBS due to the gut becoming more sensitive including an acute episode of gastroenteritis or food poisoning, bacterial infections, dysbiosis (an altered balance of the good and bad bacteria in your large bowel) or SIBO (small intestinal bacterial overgrowth which is when there are too many bacteria in the small intestines).

Irritable Bowel Syndrome Diagnosis:

The symptoms of IBS overlap with other common gastrointestinal diseases such as coeliac disease, endometriosis, and inflammatory bowel disease so it is important to speak to your GP about your symptoms to rule out these other diseases before IBS can be diagnosed.

IBS can be diagnosed by a qualified health professional, such as your GP, once they have carefully reviewed your individual symptoms, completed a physical examination, and undertaken diagnostic testing. 

IBS is based on abdominal pain with the hallmark of an IBS diagnosis being abdominal pain in the presence of bowel changes. This means that the frequency or consistency of your bowels change when abdominal pain occurs and may either present as diarrhea, constipation, or a mixture of both.

IBS can be categorized into the following categories, based on your bowel habits:

  • IBS with constipation (IBS-C)
  • IBS with diarrhea (IBS-D)
  • IBS with both constipation and diarrhea (IBS-M)

Symptoms of IBS may occur over a long period of time and have the tendency to come and go, they may also change over time (that being a change in severity and type).

It is important that certain “red flags” are investigated and ruled out before a diagnosis of IBS can be determined. These red flags include blood in your stools, unintentional weight loss, abnormal blood tests, family history of gastrointestinal diseases such as IBD, coeliac disease, or colon cancer.

If the results of a physical examination come back with no abnormalities, the Rome IV Diagnostic Criteria for IBS will then be used to diagnose IBS.

The Rome IV Diagnostic Criteria For IBS

Recurrent abdominal pain, on average, at least one day per week in the last three months, associated with two or more of the following:

  1. Related to defecation
  2. Associated with a change in frequency of stool
  3. Associated with a change in form of stool (appearance)

These criteria must also be fulfilled for the last 3 months with symptom onset or at least 6 months prior to diagnosis.

What Is The Best Treatment For IBS?

IBS presents differently in everyone, which means there is no one size fits all approach to managing it. The treatment of IBS is highly individualised with the goal of treatment being to achieve satisfactory symptom relief.

The treatment of IBS can involve a number of strategies that target diet, stress, and psychological factors including medications and complementary therapies. The implementation of these strategies is dependent on your individual symptoms and triggers.

Common Treatment Strategies Can Include:

  • Managing stress
  • Counseling services
  • Working alongside a dietitian to identify potential eating habits/behaviors that may be triggering symptoms
  • Implementing a Low FODMAP diet, under the guidance of your dietitian to identify any potential food triggers.
  • Medications or complementary therapies such as antispasmodic medications or peppermint oil to help relieve abdominal pain after eating* 
  • Probiotics*
  • Fibre supplementation- increasing your intake of soluble fibre may help to relieve constipation
  • Medications for diarrhea management such as loperamide

*Have a potential benefit but there is a lack of scientific evidence.


Your dietitian’s first priority will be in helping you to feel better. Many people notice improvements in their IBS symptoms via changes to their diet, stress management techniques, and if required prescribed medications.


Dietary Strategies That May Be Implemented Include:

  • Reducing your consumptions of high fat and/ or high sugar foods, spicy foods, foods high in insoluble fibre, artificial sweeteners, coffee, alcohol
  • Reducing the size of your meal
  • Implementing mindful eating
  • Increasing your water intake 
  • Ensuring you are chewing your food well.



If you don’t notice adequate symptom relief with the above dietary changes the second line of treatment is the implementation of a low FODMAP dietary approach.


What Is A Low FODMAP Dietary Approach?

FODMAPS stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. They are a group of sugars that are poorly absorbed in the gut and travel to the large intestine where they act as food for the good gut bacteria and undergo fermentation or they draw water into the gut via osmosis. These natural processes can cause symptoms of bloating, gas, diarrhea, abdominal pain, and constipation in particular individuals with gut sensitivities. and 

A low FODMAP diet involves an elimination, reintroduction, and personalization protocol under the guidance of your dietitian to determine your individual triggers and tolerance levels and to ensure dietary adequacy with symptom relief.

If the implementation of a low FODMAP diet does not result in adequate symptom relief your dietitian will work with you to implement other dietary strategies and work alongside other health professionals to assist in finding you adequate symptom relief.



Helpful Resources On IBS Include:

  1. IBS central: Monash: https://www.monashfodmap.com/ibs-central/
  2. About IBS: IFFGBD https://www.aboutibs.org/
  3. Diet and Irritable Bowel syndrome resource: https://www.health.qld.gov.au/__data/assets/pdf_file/0034/674386/gastro_ibs.pdf

If you are suffering from IBS and need assistance in finding adequate symptom relief or need guidance around food intolerances or implementing the Low FODMAP diet, need help with your nutrition, are unsure of what to eat, or are after nutrition advice, book an appointment with our dietitian today!

Laura Goodridge, Dietitian & Nutritionist at Total Balance Healthcare.

This blog post is an educational tool only.  It is not a replacement for medical advice from a registered and qualified doctor or health professional.

Any other questions not answered here? Get in touch with us!

Phone: 0397738085

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