Update on the Low FODMAP Diet for IBS

February 2, 2023 ,

The low FODMAP diet for IBS was created by researchers at Monash University in Australia in the 2000s. Since that time many scientific studies have been published on this subject. I will examine the current findings in this article.

Irritable Bowel Syndrome (IBS) – Diagnosis

Irritable bowel syndrome (IBS) is defined by the Rome IV criterion, which states that a person may have IBS if they experience recurrent abdominal pain at least once a week on average for the past three months, and if this pain is associated with at least two of the following criteria:

  • Defecation;
  • A change in stool frequency;
  • change in the shape or appearance of the stools.

Before concluding a diagnosis of IBS, it is important to rule out celiac disease via an antibody test, and to refer patients for further examination if they have any red flag indicators. These include unintentional and unexplained weight loss, rectal bleeding, a family history of bowel or ovarian cancer, a change in bowel habits towards softer or more frequent stools persisting for more than six weeks in a person over 60 years of age, abdominal or rectal mass, anemia, or elevated markers of inflammatory bowel disease.

The Low FODMAP diet for IBS

The low FODMAP diet represents a therapeutic avenue for people who suffer from IBS. However, before attempting this diet, it is first recommended to adopt healthy lifestyle habits such as those described by the National Institute for Health and Care Excellence (NICE) and the British Dietetic Association. These include adequate hydration, adequate dietary fiber intake, a regular meal schedule, chewing well, as well as reducing consumption of coffee, alcohol, and sparkling drinks.

What are FODMAPs?

FODMAPs refers to certain short-chain carbohydrates that can be poorly digested and thus cause digestive symptoms in people with IBS. The acronym stands for:

Fermentable: These are fermentable carbohydrates
Oligosaccharides: Includes fructans and galacto-oligosaccharides (GOS)
Disaccharides: This is lactose
Monosaccharides: This is fructose (when it is found in excess of glucose)
Polyols: Includes sorbitol and mannitol

Thus, there are 5 families of FODMAPs: fructans, GOS, lactose, fructose, and polyols. These different types of carbohydrates are found in a variety of foods. For a list of the main foods in each family, please refer to this article.

FODMAPs can cause digestive symptoms via several mechanisms. First, they are poorly absorbed by the small intestine and then fermented by bacteria in the colon, which can result in digestive symptoms, including excessive gas production and bloating. Their presence in the colon also creates a need for water and can lead to diarrhea. It is important to understand that ingesting foods that are high in FODMAPs causes symptoms only if their digestion causes an abnormal or excessive intestinal response. It should be noted that more recent studies suggest that the contribution of FODMAPs to the pathophysiology of IBS is much more complex than previously thought. Indeed, studies in rodents suggest that a high-FODMAP diet may increase intestinal permeability, visceral sensitivity, and mast cell activation.

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Kathryn Adel
Kathryn holds a Bachelor Degree in Nutrition as well as a Bachelor and a Master Degree in Kinesiology, all from Laval University. She is a Registered Dietitian and active member of the Ordre professionnel des Diététistes Nutritionnistes du Québec (ODNQ) and of the American Academy of Nutrition and Dietetics. She holds the Monash University's certification for the FODMAP diet and IBS, and has considerable clinical experience in that area. She is also an accomplished athlete, having ran track and cross-country at a national level. Kathryn specializes in sports nutrition, weight loss, diabetes, as well as heart and gastrointestinal health.

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