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Low FODMAP Diet for IBS

Nurses need to stay current in the latest nutrional trends, and how they relate to the treatment of GI disorders. With that in mind, here is everything a nurse needs to know about using the low FODMAP Diet for treating IBS (Irritable Bowel Syndrome.)

What is IBS?

Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder. It’s characterized by frequent abdominal pain and discomfort, without any other disease or injury which could explain the pain. This pain or discomfort is also accompanied by changes in stool (diarrhea, and/or constipation), as well as bloating and gas. IBS isn’t actually a disease; rather, it’s a disorder, characterized by a set of symptoms. It’s an often misunderstood disease with little agreement as to what causes it, as well as how to treat it.

What are FODMAPs?

FODMAPs refer to a group of foods with certain types of sugars in them. It is actually an acronym for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. These sugars are also commonly known as fructose, lactose, and galactans. High FODMAP foods include (but are not limited to) dairy products, HFCS (high fructose corn syrup), wheat, onions, garlic, watermelon, cherries, cauliflower and most beans. For a more comprehensive list of low vs. high FODMAP foods, check out Kate Scarlata’s list. She’s a Registered Dietitian who blogs about IBS and the low FODMAP diet.

What is the connection between FODMAPs and IBS?

Dr. Sue Shepherd is the pioneering dietician who first began researching the connection between FODMAPs and IBS. The theory is that IBS can be caused by the malabsorption of these sugars. The sugars cannot be absorbed by the small intestine, and so therefore travel to the large intestine. This is where they wreak the havoc that we commonly know as IBS. The sugar molecules are fermented (the “F” in FODMAP) by the large intestinal bacteria, causing osmotic imbalances that contribute to bloating, gas and diarrhea.

How effective is the diet?

Does the low FODMAP diet for IBS actually work? The research undertaken by Dr. Shepherd at Monash University showed that IBS symptoms were alleviated in 74% of those who undertook the diet. Further studies have confirmed this, but more research is needed. Research is perhaps hindered by the difficulty in administering the diet.

What are the steps to this diet?

First of all, the diet should be administered under the supervision of a registered dietician. It’s a very difficult diet to follow, as the foods that fall under the high fodmap category are ubiquitous. All processed foods must be checked carefully for hidden high FODMAP ingredients like onion and garlic powder, as well as HFCS and inulin.

The diet is started by eliminating all foods in the high FODMAP category for two weeks. If improvement in IBS symptoms is seen, then it is recommended to add back foods one at a time, to assess the sensitivity to each food. It is possible that some IBS patients may be sensitive to polyols (onions, garlic, etc) but not to fructans (gluten, certain fruits.). Or one might be able to tolerate lactose (in dairy products) but not galactans (found in beans). There is a lot of will power required, as well as trial and error. An experienced dietitian helps the patient to determine which foods are IBS triggers and which foods can be tolerated.

Further Resources

More information about treating IBS with the low FODMAP diet:
Monash University low FODMAP information
Dr. Sue Shepherd’s low FODMAP information
Kate Scarlata, RDN
TheDustyApron.com: Healthy Eating to Beat IBS


  1. Jesse Watson says:

    Hi Beth, thanks for the article! I love seeing this diet gaining the attention it deserves! My wife is a dietitian who has had IBS for 20 years, and the low FODMAP diet absolutely changed her life. So much so that we’ve decided to start the country’s first all natural, low FODMAP food company – we are at https://nicerfoods.com for those interested. Beth, if you are US-based, feel free to email me at jesse@nicerfoods.com if you’d like some sample of our protein bars to give to clients starting out on this diet.

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