Irritable Bowel Syndrome (IBS) is a chronic health condition that affects both physical and mental health. Research estimates that up to 1 in 5 people suffer from this condition, however this number may be higher.


IBS is a digestive disorder that is characterised by chronic, relapsing abdominal discomfort, abdominal bloating and altered bowel habits. Between IBS sufferers, symptoms often vary and can include a combination of diarrhoea, constipation, excess flatulence, abdominal cramping and constant bloating.

IBS is classified as a functional disorder, meaning the above-mentioned symptoms occur in the absence of other structural or biochemical abnormalities.


Unfortunately the cause of IBS is unknown, however we know that it is likely multi-factorial, meaning a number of factors contribute to the condition. Some of these include, an altered gut-brain connection, a hypersensitive bowel, inflammation and alterations in the gut microbiota.


IBS cannot be diagnosed by a simple test, rather it will be diagnosed based on a collection of re-occurring gastrointestinal symptoms. Before assessing for IBS however, more sinister gastrointestinal conditions will be first ruled out, including Coeliac Disease, Inflammatory Bowel Disease, Colon cancer and infections. This is why it's always important to check in with your doctor, before self-diagnosing.

The Rome IV Criteria

The Rome IV Criteria is a diagnostic method used to assess for IBS, as well as classify the sub-type of IBS an individual has. The criteria is as follows:

If a person has experienced…

  • Recurrent abdominal pain on average once per week for 3-6 months, plus 2 or more of the below issues,

  • Symptoms related to defecation (e.g. discomfort)

  • Changes in the frequency of bowel motions (e.g. once every 3 days, or more than 3 times per day)

  • Changes in the form of stools (e.g. watery, or hard pellets)

Then an IBS diagnosis will be made.

Further to this, the IBS sub-type will be classified as either:

  • IBS-C (constipation predominant)

  • IBS-D (diarrhoea predominant)

  • IBS-M (mixed)


There is currently no cure for IBS, however specific therapeutic diets, stress management, good quality sleep, plus exercise can significantly help in managing symptoms. One such therapeutic diet is the low FODMAP diet.


The low FODMAP diet is a specific eating plan that has proven to relieve symptoms in more than 75% of people suffering from IBS.



The word FODMAP is an acronym that stands for Fermentable Oligiosaccharides, Disaccharides, Monosaccharides and Polyols. These are all specific types of carbohydrates that resist digestion, end up in the large intestine, and are rapidly fermented by bacteria. When FODMAPs are fermented, gases are produced that can trigger IBS symptoms. Further to this, FODMAPs can have an osmotic effect in the gut, meaning they can draw water into the digestive tract resulting in further symptoms, such as loose stools.


The low FODMAP diet is currently the best treatment for IBS management.


The low FODMAP diet consists of THREE phases:

  1. Elimination phase – low FODMAP diet

  • All moderate to high FODMAP foods are eliminated for a period of 2-6 weeks.

  1. Challenge phase – FODMAP challenges

  • There are six specific categories of FODMAPs that are challenged at a low dose, then a high dose. This often takes 6 or more weeks.

  1. Maintenance phase – individualised modified FODMAP diet

  • After all FODMAP challenges have been completed, a modified and individualised FODMAP diet is planned out.

Extra considerations for the low FODMAP diet

Is it highly recommended that you work with a qualified Dietitian (APD) who specialises in gut health and the low FODMAP diet. This is because of the complexity of the diet and challenge phase, as well as nutritional requirements that can be altered during the diet. Particular nutritional requirements that can become compromised include fibre, prebiotics, calcium and iron, as well as overall nutritional quality.