What is Irritable Bowel Syndrome?

Irritable Bowel Syndrome (IBS) is a common functional gastrointestinal disorder affecting one in seven Australian adults and is also common in the North America and Europe. The incidence of IBS in Asian countries is increasing exponentially as a Western style diet becomes more common. According to the American College of Gastroenterology, 50 million people suffer with IBS.

IBS is sometimes difficult to diagnose because there are no abnormalities in blood tests or other investigations, such as colonoscopy or gastroscopy. The diagnosis of IBS should be made by a medical practitioner.

Despite this, IBS is very debilitating, ongoing and relapsing. Symptoms include;

  • lower abdominal pain and discomfort,
  • bloating, wind, abdominal distension
  • altered bowel habit (ranging from diarrhoea to constipation)
  • no abnormal pathology.

Some of the factors contributing to IBS can be:

  • stress
  • diet
  • altered digestive bacteria (gut biome)
  • medications.

Interesting facts about IBS:

  • 10% of GP visits and between 20 – 50% Gastroenterologist visits relate to IBS
  • IBS is the 2nd most common cause of absenteeism in Australia
  • People with IBS have 50% higher medical costs than general population
  • Quality of Life of IBS sufferers equivalent to this with Chronic Kidney Disease.

Diet and IBS

Gastrointestinal symptoms amongst people who have tested negative for coeliac disease were previously considered gluten intolerant because they responded well to a gluten free diet. It is now recognised in the scientific literature that what was considered an intolerance to the protein component of wheat, can be alleviated using a low FODMAP diet, and is therefore related to the carbohydrate component of grains. (Biesiekierski et al (2013) Gastroenterology 145, pp 320-328.e3. Halmos et al (2014) Gastroenterology 146:67–75)

FODMAPs (i.e. Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols) are a collection of carbohydrates found in food and can be poorly absorbed by some people, particularly those suffering from IBS. The low FODMAP diet is increasing in public awareness at an exponential rate, and in Australia a labelling system for grocery items is now available:

To learn more about the science behind this new dietary approach to IBS go to the Monash University publications.

1 million Australians consume gluten-free products because they report feeling better.

However 90% of these people would feel just as good or better on a low FODMAP diet.

What are FODMAPs  and their role in IBS Symptoms?

The acronym FODMAP stands for:

  • FERMENTABLE  = The process through which gut bacteria degrade undigested carbohydrate to produce gases (hydrogen, methane and carbon dioxide)
    • Fructo-oligosaccharides (FOS) found in; wheat, rye, onions and garlic
    • Galacto-oligosaccharides (GOS) found in ; legumes/pulses
  • DI-SACCHARIDES = Lactose is the “double sugar” in; milk, soft cheese, yoghurts that gets broken down by bacteria, enzymes or fermentation
  • MONO-SACCHARIDES, AND = Fructose (in excess of glucose) found in honey, apples, high fructose corn syrups
  • POLYOLS = Sugar polyols (eg. sorbitol, mannitol) found in some fruit and vegetables and used as artificial sweeteners.

1. Foods containing FODMAPs are consumed as part of a regular diet.

2. Some FODMAPs draw fluid into the bowel, resulting in diarrhoea.

3. The balance of healthy and unhealthy digestive bacteria can get out of balance in individuals with IBS.

4. When bacteria in the large bowel break down fermentable carbohydrates, this can create gases that result in the pain, bloating and wind associated with IBS.

5. Some individuals may be more sensitive to the gases created by gut bacteria when they break down fermentable carbohydrate in the large bowel.

IMPORTANT NOTE: Fermentable carbohydrates are important for feeding the healthy digestive bacteria that have many health benefits. Only cut down FODMAPs as much as necessary and for as long as necessary to minimise symptoms.