Guest Author: Clarissa Lenherr, gut health expert and nutritionist. To find out more about Clarissa, click here.

What is IBS?

IBS is a common gastrointestinal condition that impacts how the gut functions and often triggers a change in bowel movements or bowel habits. There are often no structural changes or actual disease within the gut, but symptoms tend to occur due to a change in how the gut is functioning.

IBS symptoms are different for everyone, but the most common symptoms tend to include:

  • Bloating
  • Cramping
  • Changes in bowel movements/ stool consistency
  • Constipation
  • Diarrhoea

There are four main sub-types of IBS, and treatment will depend on which type you may have:

  • IBS-D - Diarrhoea dominant
  • IBS-C - Constipation dominant
  • IBS-M - mixed bowel movements
  • IBS -U – unsubtyped

Although IBS may not be life-threatening, it can significantly affect an individual’s quality of life.

What are the causes of IBS?

There is no one cause of IBS. Most of the time it is a combination of factors that are unique to each individual.

Potential causes may include:

  • Stress levels and lifestyle factors
  • Diet
  • Genetic factors
  • Altered motility in the gut
  • Medication use such as antibiotics
  • Sensitivity in the gut wall
  • Changes to the Gut-brain axis
  • Chronic infections and dysbiotic gut microbiota
  • Post-infectious IBS

If someone suspects that they have IBS, how can they get a diagnosis?

There is no blood or stool test to confirm if someone has IBS. To get a diagnosis, a doctor will normally run through a tick box collection of symptoms that is used as classification. If you struggle with gut symptoms for 3 months or longer, it is recommended that you reach out to your GP. 

Your doctor may wish to rule out celiac disease, inflammatory bowel disease’s such as Ulcerative Colitis and Crohn’s, as well as checking for anatomical changes.



Your doctor may prescribe medication, depending on your presentation of symptoms.

This can include:

  • Fibre supplements - to help those with constipation
  • Laxatives - if fibre does not help and if constipation is severe
  • Anti-diarrhoea medications
  • Anti-spasmodic drugs
  • Tricyclic antidepressants or SSRI antidepressants
  • Pain medications


Your doctor, dietician or nutritionist may recommend that you try the low fodmap diet. This is an elimination diet that was developed by Monash University to help manage IBS symptoms.

The diet involves removing food groups (high FODMAP foods) that are not easily broken down in the digestive system, and after a period of elimination, re-introducing them one by one in different portion sizes, to test your personal tolerance.

FODMAP (which stands for Fermentable, Oligo-, Di-, Mono-saccharides and Polyols) foods are those that contain short-chain carbohydrates that are poorly absorbed in the small intestine and therefore travel undigested into the large intestine. When they arrive in the large intestine, they are fermented by gut bacteria that turn these carbohydrates into gas. This gas stretches the walls of the gut triggering pain, cramping, bloating etc.

This process is totally natural, but if you're prone to IBS symptoms, the gas produced can cause additional stomach troubles.

The different FODMAP groups:

  • Fermentable: The process where our gut bacteria ferment undigested carbohydrates to produce gases
  • Oligosaccharides- Fructans and GOS- Found in: wheat, rye, pulses, legumes, cashews and various vegetables such as garlic and onion
  • Disaccharides- Lactose- Found in: dairy products such as ice cream, yogurt, milk, custard and soft cheese
  • Monosaccharides- Fructose- Found in: Honey, fruit juice and fruits such as figs and mangoes
  • Polyols- Sorbitol and Mannitol- Found in some artificial sweeteners, and certain vegetables and fruits including blackberries and lychees

Many foods contain FODMAPs, so it is impossible to remove them all, and not advised or necessary. Many of these FODMAP containing foods don't usually become troublesome until a larger quantity of the food is consumed. Therefore, they can often be tolerated in smaller portion sizes.

Please note that the low FODMAP diet is a short term diet and is not intended for long-term use. It is always advised to work with a healthcare provider when following the low fodmap diet, as it is incredibly complicated and needs to be managed to achieve the best outcome.


Fibre is a complex carbohydrate that is made up of plant compounds that cannot be digested or absorbed by the small intestine. Instead, fibre is broken down in the large intestine by our gut bacteria.

Increasing your intake of fibre may be suggested if you suffer with IBS-C or have inconsistent bowel movements. There are two main types of fibre to focus on when supporting optimal bowel movements:

  • Soluble fibre - that help to bulk out your stool - found in foods such as apples, oats and beans
  • Insoluble fibre - helps draw water into your stool, making it easier to go - cauliflower, nuts, beans and whole-wheat flours

Regardless of symptoms, we should all be aiming for the RDI of 30g of fibre per day to help support bowel movements and give our good gut bacteria fuel.

When struggling from IBS, there are a number of ways you can manage your symptoms whilst still getting in enough fibre:

  • Start low and slow- Start introducing fibre slowly, and let your body get used to the increased fibre load in small amounts, rather than all at once.
  • Choose low FODMAP fibre sources
  • As your digestive system starts to adjust, keep in mind that soluble fibre from foods such as nuts, seeds, beans and fruit can promote more gas formation than insoluble fibre foods such as grains and vegetables.


Probiotics are live bacteria and yeasts that help to restore the natural balance of bacteria in the gut. Each of us have trillions of bacteria living inside us, and it is suggested that about 1-2kg of bacteria can be found just in the gut! Due to stress, illness or medication use, the balance of bacteria in the gut may become altered, which in turn may potentially be a trigger or mediator for digestive symptoms.

It is thought that probiotics, whether taken as a supplement or found in food forms (fermented foods) may help to bring balance back to the gut microbiome, and reduce symptoms for some individuals.

Although probiotics aren't recognised as a treatment for IBS, a high percentage of people who suffer with IBS, claim that probiotic supplements help to tone down symptoms better than any IBS medication. It’s important to remember that every person is individual and will have different results when it comes to taking probiotics, due to every person's gut microbes and microbiota being totally unique.

If you want to try a probiotic, it is best to opt for a multi-strain option that has a minimum of 1 billion CFU and try it out for at least three months to see if this brings you any symptom relief.

If you think you have IBS it is important to work closely with a healthcare professional to rule out other conditions and get first stage advice. Contact your GP to get a diagnosis and from there work with a gut specialist nutritionist or dietician to work with you to get to the root cause and manage your symptoms.