Functional Gastrointestinal Disorders – including Irritable Bowel Syndrome (IBS)

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Bloating, abdominal discomfort and distention and changed bowel patterns may be all too familiar to people who suffer from functional gastrointestinal disorders. What is so frustrating for most is that trying to figure out the cause of these symptoms seems like searching for a needle in a haystack.

What is functional gastrointestinal disorder?

Functional gastrointestinal disorders is a term used to describe disorders, including IBS where there is impairment in the intestines normal activities, the sensitivity of nerves in the intestines and the way in which the brain controls these functions — yet there is no structural abnormality in the intestines.

The most common functional gastrointestinal disorder is irritable bowel syndrome (IBS) which affects 3 – 15% of people in the western populations (Escott-Stump, 2012). Although all of us have had the occasional symptoms of bloating, diarrhea and abdominal discomfort the amount and frequency of these symptoms is what determines the difference.

Since there are no structural abnormalities in the intestine (which are present in diagnoses like Celiac disease, Crohn’s or Colitis), IBS is determined on the basis of symptoms using the Rome III diagnostic criteria. Someone who has experienced 3 months or more of continuous or re-occurring gastrointestinal symptoms that are relieved with a bowel movement is said to have IBS.

What is IBS?

IBS and its symptoms are associated with change in the frequency and consistency of stools (Escott-Stump, 2012). While the primary cause of IBS is not fully known, approximately one in ten patients suffering from IBS symptoms believe their IBS is result of an infectious illness. This belief has been born out in the research. Recent studies have shown that 3 – 36% of intestinal infections lead to IBS symptoms (Escott-Stump, 2012).

More commonly, IBS patients associate their symptoms to food allergies and food sensitivities and this can be assessed by a Dietitian specializing in this area. Sometimes symptoms are linked to a lack of sufficient enzymes to digest a particular food, such as lactose in milk and dairy products.  An experienced Dietitian can determine whether the problem is with an allergy to casein, for example (a protein contained in milk and dairy) or with lactose, a sugar in milk and dairy.

Ruling out something more serious

The most important first step in diagnosing and treating IBS is to rule out that something more serious is going on, such as Celiac disease (also called “gluten intolerance”) because even small amounts of gluten in the diet of such individuals causes serious damage to the intestine.  A simple blood test can be done but for it to be accurate, one has to still be eating gluten containing products.

Sometimes people self-diagnose themselves and stop eating these foods, no longer making it possible to determine if something more serious is going on.  It’s best to see a health care professional such as your doctor and a Registered Dietitian specializing in this area to rule out Celiac disease, before going gluten free.

Other diagnoses that need to be ruled out as well are more severe intestinal disorders such Inflammatory Bowel Disease (IBD) such as Crohn’s and Ulcerative Colitis).  Once food allergy and IBD have been ruled out, diagnoses and treatment of IBS can begin.

Dietary Management of IBS

While there is no one-size-fit-all dietary treatment for IBS, there are some foods that have been shown to trigger IBS symptoms in many individuals.  When these are limited or avoided in the diet, many people’s symptoms improve significantly. For some people, foods that trigger IBS symptoms are high fat or fried foods.  These can be determined from keeping a specific type of food journal with the time food is eaten and the time and type of symptoms experienced.  When reviewed by a knowledgeable and experienced Dietitian, a pattern emerges.

Natural sugars in foods such as fructose are also known to cause gastrointestinal symptoms because fructose isn’t as easily absorbed in the intestine as other natural sugars (Barrett et al, 2007). However, fructose is just one member of a family of small poorly absorbed carbohydrates. With the common tendency for people to blame carbohydrates for all sorts of problems, it’s important to note that not all carbohydrates are equal.

Long Chain and Short Chain Carbohydrates

Carbohydrates are large macronutrients that are made up of small individual molecules connected together just like a freight train. So, using that analogy, carbohydrates can be either ‘short freight trains’ or ‘long freight trains’. It tends to be these short chain carbohydrates that tend to be the problem for people who suffer with IBS. There have been increasing studies supporting the ideas of limiting these short-chain carbohydrates using something called the low FODMAP diet to manage IBS symptoms (Thomas et al, 2012).

What are FODMAPs?

FODMAP is an acronym for this group of short chained carbohydrates; literally fermentable, oligo-, di-mono-saccharides and polyols. These short chain molecules have 3 common functional properties (Gibson et al, 2010). Figure 1.

1. they are poorly absorbed in the small intestines and as a result, they build up in the intestines.

2. they have a laxative effect because these small unabsorbed molecules build up in the intestines, cause water to be drawn into the intestines which results in bloating  or abdominal distention, cramping and often diarrhea.

3. they are

a great food source for bacteria that are naturally present in the intestines which can result in gas production.

Symptoms such bloating, cramping, diarrhea, abdominal discomfort can occur in people who are sensitive to the effects of these FODMAPs in their diet and these people may find some relief when they consume a diet low in FODMAPs.

IBS symptoms

Figure 1. Theoretical relationship between FODMAPS and gastrointestinal symptoms (adapted from Barrett et al, 2007).

Will my nutrition be limited in a low FODMAP diet?

It is true that the low FODMAP diet limits several different types of carbohydrates and can appear quite restrictive but with endless amount of alternative foods in the market and careful meal planning, a healthy balanced diet can be achieved. This where working with a knowledgeable and experienced dietitian is essential.  We provide nutritional support for IBS while helping you make sure to get adequate nutrients from foods low in the substances that underlie your symptoms.

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Barrett, Jacqueline S. and Gibson, Peter R. Clinical Ramifications of Malabsorption of Fructose and Other Short Chain Carbohydrates. Nutrition Issues in Gastroenterology (in Journal of Practical Gastroenterology). 2007 August (53) 51-65

Escott-Stump, Sylvia. Nutrition and Diagnosis Related Care. Seventh Edition. Baltimore and Philadelphia: Lippincott Williams and Wilkinks, a Wolters Kluwer business, 2012.

Gibson, Peter R.  and Shepherd, Susan J. Evidence Based Dietary Management of Functional Gastrointestinal Symptoms: The FODMAP Approach.  Journal of Gastroenterology and Hepatology. 2010 February (25) 252-258.

Thomas, R,, Nanda, R., Shu, Lin H. A FODMAP diet update: Craze or Credible? Nutrition Issues in Gastroenterology (in Journal of Practical Gastroenterology).2012 December (112) 37-46.