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FODMAPs 101: A Detailed Guide to Low-FODMAP Diet

Screen Shot 2016-04-28 at 11.34.07 AMWhile FODMAP may look like an abbreviation for a government agency or subway system, this clunky acronym is the name of a hugely popular diet which has actually helped smooth the tummy troubles of millions around the world.

Sue Shepherd developed a form of fructose malabsorption diet. Subsequently a team at Monash University, led by Professor Peter Gibson and including Dr Shepherd and others, developed the low FODMAP diet.

They found that limiting FODMAP foods is an effective way of addressing a number of gastrointestinal conditions including:

  • Irritable Bowel Syndrome
  • Coeliac Disease
  • Fructose Malabsorption
  • Lactose Intolerance
  • Crohn’s Disease
  • Ulcerative Colitis


What are FODMAPs?

FODMAPs are found in a number of our food and have been found to be poorly absorbed by those with gastrointestinal issues, especially irritable bowel syndrome (IBS).

FODMAPs is an acronym for:

Oligosaccharides (eg. Fructans and Galacto-oligosaccharides (GOS))
Disaccharides (eg. Lactose)
Monosaccharides (eg. excess Fructose)
Polyols (eg. Sorbitol, Mannitol, Maltitol, Xylitol and Isomalt)


When these molecules are poorly absorbed in the small intestine of the digestive tract, they errantly continue their journey arriving at the large intestine.

Here they act as a food source to the bacteria that live there normally. The bacteria then digest/ferment these FODMAPs and can cause symptoms of IBS.


The primary oligosaccharides are fructans and galacto-oligosaccharides (GOS)).


Fructans are chains of fructose molecules with a glucose molecule at the end. Dietary sources are wheat products (breads, cereals and pasta) and some vegetables such as onions.

There are also fructo-oligosaccharides (FOS) and inulin which are added to foods such as some yoghurts and milks.

No-one is able to digest fructans and they are the most common FODMAP to cause symptoms of IBS.

For those with IBS, fructans become an issues if they contain more than 0.2 grams per serving for cereals and grains and 0.3 grams per serving for other fructan rich foods.


Galacto-oligosaccharides (GOS)

Galacto-oligosaccharides are chain molecules formed from galactose sugars joined together with a fructose and glucose at the end.

They occur in many legumes such as beans, lentils and chickpeas. GOS cannot be digested or absorbed by anybody and should be avoided by any one who has IBS.

High GOS foods are those that contain more than 0.2 grams per serving.



The primary disaccharide is lactose.


Lactose is a double sugar (glucose and galactose) that occurs in all animal milks such as cow, sheep and goats. Lactose is broken down by an enzyme called lactase in the small bowel.

However many individuals have low levels of lactase and can only break down a small amount of lactose. This is known as lactose intolerance.

It is important to note that a lactose free diet is not a dairy free diet as many dairy products are almost lactose free. These include some yoghurts, some soft and hard cheeses and cream.

Most people can ingest up to 4 grams of lactose per serving without problems.


The main monosaccharide is fructose.


Fructose is a single sugar found in every fruit, honey, table sugar, some vegetables and high-fructose corn syrup. Fructose tends to be better tolerated if it occurs with glucose as it is ‘piggy-backed’ across the bowel lining.

However if fructose is in higher levels it is absorbed at a slower rate. If this absorption is incomplete it is termed fructose malabsorption.

Foods are considered a problem for IBS sufferers if they contain more than 0.2 grams fructose in excess of glucose per serving.


Examples of Polyols are Sorbitol, Mannitol, Maltitol, Xylitol and Isomalt. They are sugar alcohols and occur naturally in some fruits and vegetables.

Foods are considered a problem for IBS sufferers if they contain more than 0.5 grams total polyols per serving.


Should a person determine that they are sensitive to any of the above FODMAPs, a low FODMAP diet is recommended.


Diseases Low FODMAP Diets Have Been Shown to Improve:

Irritable Bowel Syndrome

IBS-irritable-bowel-syndromeSymptoms of Irritable Bowel Syndrome (IBS) include abdominal bloating and distension, excess wind (flatulence), abdominal pain, nausea, changes in bowel habits (diarrhoea, constipation, or a combination of both), and other gastro-intestinal symptoms.

There is no abnormal pathology.

The low FODMAP diet has been shown to improve gastrointestinal symptoms in 3 out of 4 people with IBS, meaning a small percentage of people with this condition do not respond to the diet.

So what should a ‘non-responder do’?

A practitioner should be sought who is able to check the diet for hidden sources of FODMAPs or any additional dietary triggers that may be aggravating symptoms, such as caffeine, alcohol and/or spicy foods.

If there is still no improvement in symptoms, it might be worth returning to a Gastroenterologist for further investigations, or seeing a Naturopath or dietitian to investigate other dietary triggers, such as naturally occurring food chemicals (salicylates, amines and glutamates) that may be responsible for triggering IBS symptoms in a small proportion of people.


Coeliac Disease

Coeliac disease affects 1 in 100 Australians, and is one of the world’s most under-diagnosed diseases. The disease affects both sexes and it can begin at any age, from infancy (as soon as cereals are introduced) to later in life.

Coeliac disease is an autoimmune disease, meaning it is caused by the body’s own immune system mistakenly attacking healthy cells, organs, or tissues in the body that are essential for good health.

In a person with coeliac disease, eating gluten, the protein component of grains like wheat, rye, barley and oats, causes inflammation of the small intestine, the part of the digestive system responsible for absorbing nutrients from the diet.

When the lining of the small intestine is damaged, nutrients like calcium, iron, folic acid and fat-soluble vitamins are not absorbed properly.

Sugars, proteins and fats may also be poorly absorbed. Malnutrition, osteoporosis, depression and infertility are just some of the problems that can develop if the disorder is left untreated.

Coeliac disease is difficult to diagnose because it is not often characterised by specific complaints. Different people may experience different symptoms. The most common symptoms in adults include:

  • Anaemia (iron deficiency)
  • Bloating and flatulence
  • Diarrhoea or constipation
  • Fatigue, weakness and lethargy
  • Nausea and vomiting Stomach cramps
  • Weight loss

Fructose Malabsorption

006_StomachPainChecklist_MEDIAFructose is a sugar found in fruits, vegetables and processed foods.

It can exist in food as a free sugar, a disaccharide (sucrose) and/or in a polymerised form (fructans) and relies on a facilitative transport system (GLUT5) for uptake from the small intestine.

Up to half of the population are unable completely absorb any more than 25 g per day, this is equal to 2 apples and one banana.

Unabsorbed fructose travels to the bowel where it can ferment and cause bloating and flatulence. Other common adverse effects can include diarrhoea, reflux, abdominal pain and dysbiosis.

Lactose Intolerance

Lactose intolerance is a general description used for people who cannot easily digest lactose, a sugar found naturally in animal milk.

Lactase, the enzyme in the digestive system that helps break down lactose, declines from the age of two. Symptoms of lactose intolerance may include abdominal pain, gas, cramping, bloating, diarrhoea or constipation.

Crohn’s Disease

Crohn’s disease begins with chronic inflammation (it is known as an inflammatory bowel disease (IBD)), most often in the lower part of the small intestine (ileum) or in the colon, but sometimes in the rectum, stomach, oesophagus or mouth.

Symptoms include: diarrhoea, abdominal pain and cramping, blood in the stool, ulcers and reduced appetite and weight loss.

Ulcerative Colitis

Ulcerative Colitis and Crohn’s Disease are both very similar, however ulcerative colitis usually affects the innermost lining of your large intestine (colon) and rectum.


What Foods are FODMAPs Found In?

Below are some examples of food sources for each of the FODMAPs are listed below.

  • Excess Fructose: Honey, Apples, Mango, Pear, Watermelon, High Fructose Corn Syrup,
  • Fructans: Artichokes (Globe), Artichokes (Jerusalem), Garlic (in large amounts), Leek, Onion (brown, white, Spanish, onion powder), Spring Onion (white part), Shallots, Wheat (in large amounts), Rye (in large amounts), Barley (in large amounts), Inulin, Fructo-oligosaccharides.
  • Lactose: Milk, icecream, custard, dairy desserts, condensed and evaporated milk, milk powder, yoghurt, soft unripened cheeses (eg. ricotta, cottage, cream, marscarpone).
  • Galacto-Oligosaccharides (GOS): Legume beans (eg. baked beans, kidney beans, bortolotti beans), Lentils, Chickpeas
  • Polyols: Apples, Apricots, Avocado, Cherries, Nectarines, Pears, Plums, Prunes, Mushrooms, sorbitol (420), mannitol (421), xylitol (967), maltitol (965) and isomalt (953).



Eating Requirements When On a Low FODMAP Diet

The Low FODMAP diet has two phases:

First Phase of the low FODMAP Diet

The first phase generally involves a strict restriction of all high FODMAP foods. This phase should be followed for 6-8 weeks only, then an expert practitioner such as a naturopath or dietitian should be consulted for a review appointment to learn the second phase.

Second Phase
of the low FODMAP Diet

The second phase of the low FODMAP Diet allows the diet to be liberalised to suit each individual. Here the type and amount of FODMAPs are identified so that a longer term diet can be established.Read here for an easy to follow low FODMAP Shopping List


Keep Informed On The Go – Low FODMAP App

Now, thanks to the research team at the Department of Gastroenterology at Monash University, a Low FODMAP smartphone application has been created which provides accurate information about foods that trigger IBS reactions in order to help sufferers manage their symptoms.

Now available on iPhone and Android phones.


Final Word

Each person undergoing a low FODMAP diet is recommended to consult with an experienced practitioner for both phases of the low FODMAP diet as each phase involves many dietary changes and there is a large chance of confusion or even eliminating foods that don’t necessarily need to be taken out of the diet.

If you are interested in undertaking a low FODMAP diet contact one of our practitioners to organise a consultation.


Further Reading



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