Could FODMAP Malabsorption Explain Your Persistent Digestive Symptoms Despite Gluten-Free Diet?

Melinda Dennis, MS, RDNFODMAP is an acronym that stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols. The FODMAPs are a group of small chain carbohydrates (sugars and fibers) that are commonly poorly absorbed in the small (upper) intestine. These FODMAPs are naturally found in many, many foods such as apples, pears, mangoes, honey, agave syrup, milk products, watermelon, cauliflower, legumes, mushrooms, onion, garlic, wheat, rye, and barley, to name a few. They are also found in some medications and supplements as well as in artificial sweeteners (sorbitol, xylitol, mannitol, etc.,) and so appear in sugar-free or diet drinks, foods, chewing gum, mints and candies.

Malabsorption of FODMAPS is widespread among the irritable bowel syndrome (IBS) population and, from the literature, it appears that a high percentage of those with IBS see good results from a Low FODMAP diet trial. FODMAP malabsorption can also be seen in patients with celiac disease, gluten sensitivity, inflammatory bowel disease, and in other individuals with a sensitive gastrointestinal tract. Specific breath tests can diagnose malabsorption of fructose and lactose; malabsorption of the other groups is best detected through a careful review of the patient’s diet and symptoms by a skilled dietitian.

Poorly absorbed FODMAPs (the most commonly known ones being “fructose” and “lactose”) are carried to the colon (large intestine) where the normal bacteria quickly consume them. The bacteria produce gases and chemicals which cause the intestine to swell, prompting the feelings of bloating and distension, cramping, gas, fatigue, nausea and abdominal pain. Diarrhea and/or constipation are also common symptoms. As you can see, the symptoms of fructose malabsorption can mimic those of gluten exposure.

Symptoms can include (but are not limited to) gas, bloating, cramping, abdominal pain, loose stool, diarrhea, constipation, abnormal stool patterns, fatigue, headaches, nausea, and the list goes on. So, let’s explore what might be causing these persistent symptoms.

The Low FODMAP diet is a temporary diet that begins with a strict restriction of all high FODMAP foods followed by a reintroduction of the FODMAPs one group at a time. In this second phase, the type and amount of FODMAPs an individual can tolerate are identified with the goal of a varied, balanced diet for the long- term. An experienced dietitian should be consulted to help balance nutrient and fiber intake since each phase involves many specific diet changes.

For many more details on the diagnosis, symptoms, and treatment of FODMAP malabsorption, please review these excellent resources/references: Monash University Website:

Monash University Low FODMAP App for I-phone and Android:

Sue Shepherd B.App.Sci, M.Nut. & Diet., PhD Shepherd, S. The Low FODMAP Diet Cookbook. The Experiment, 2014. (Kate Scarlata, MS, RDN) (Amy Burkhart MD, RDN) Amy Burkhart MD, RDN Amy Burkhart MD, RDN Patsy Catsos, MS, RDN
Barrett JS. Extending our knowledge of fermentable, short-chain carbohydrates for managing gastrointestinal symptoms.

If you and your dietitian have reviewed your gluten-free diet and lifestyle and wish to pursue additional options, follow this series as we share Ms. Dennis’ insights on Small intestinal bacterial overgrowth (SIBO)

Other Reasons: Less common causes of continued symptoms on the gluten-free diet include, but are not limited to, microscopic colitis, pancreatic enzyme insufficiency, and refractory celiac disease (very uncommon) and can be discussed with your doctor.

Bottom line: Don’t assume it’s normal to be feeling unwell. I hear many patients say “I just assumed everyone had diarrhea twice a day and I got used to living with it.” If you are still experiencing symptoms, talk to your doctor and ask for testing. You deserve to be in excellent health.

For labeling laws in the United States and cross contamination resources, visit: (Tricia Thompson MS, RDN)

Cross Contamination: Level 3 on See

Disclaimer: As Nutrition Coordinator of the Celiac Center at Beth Israel Deaconess Medical Center, I am the lead writer and editor of the website and co-author of the book Real Life with Celiac Disease. Otherwise, I have no business/financial stake in the resources listed in my article above.

Note: The References and Further Reading resources above represent only a portion of the excellent information available on these topics. I recommend PubMed, in particular, for the multiple peer-reviewed journal articles you will find.

Would you like to immerse yourself in nutrition and health at a gluten-free weekend retreat with me in New Hampshire or Santa Barbara, California? We’ll cover all of these nutrition topics and many more in great detail.

Visit: or email me for more information: [email protected]

© 2015 Melinda Dennis, MS, RDN/Delete the Wheat. LLC. All rights reserved.

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