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  • Writer's pictureDr. Alla Arutcheva

Gluten and Fructan.Wheat doesn't contain only gluten but fructan as well.

If an individual with gluten sensitivity and fructan intolerance eliminates only gluten from the diet, fructan may continue causing gastrointestinal symptoms. A new study published in the journal Gastroenterology [Skodje GI et al. 2017] shows that in a group of people who thought they were gluten-sensitive, fructan caused more stomach upset than gluten did.

What are fructants?

Fructants are naturally occurring carbohydrates in the form of 2-9 units length fructose. Malabsorption and intolerance to carbohydrates are common problems frequently encountered in the gastrointestinal (GI) clinics. These intolerances frequently lead to unexplained GI symptoms such as abdominal bloating, gas, flatulence, pain, distension, nausea and diarrhea.

What types of foods are fructans found in?

Foods that are high in fructans include wheat products, onions, shallots, garlic, barley, cabbage, broccoli, pistachio, artichoke, chicory root, and asparagus. Each food containing fructan will have different amounts per serving.

When trying to make dietary changes to help relieve symptoms of fructan intolerance, any amount greater than 0.2 grams per serving has been seen to cause symptoms for most, although this level may vary for each person.

When an individual follows a gluten-free diet, they are eliminating about 70% of the major source of fructans.


Gluten are proteins found in grains like wheat, spelt, rye and barley. Gliadin and glutenin are the two main gluten proteins. Celiac disease is the most severe form of gluten intolerance. It is an autoimmune disease that damage digestive system.

However, 0.5–13% of people may also have non-celiac gluten sensitivity (NCGS), a milder form of gluten intolerance that can still cause problems.

How does fructan intolerance relate to irritable bowel syndrome (IBS)?

IBS affects the large intestine, and has similar symptoms as fructan intolerance. The cause of IBS is unknown, but may be triggered by food allergies or intolerance, stress, hormonal changes, or other illnesses affecting the gastrointestinal tract. Patients with IBS may experience difficulty tolerating fructans as well as other fermentable short-chain carbohydrates (fructose and lactose).

What causes fructan intolerance?

The human body has limited ability to break down these oligo- or polysaccharides in the small bowel and only absorbs 5 – 15% of fructan [Marcason W. 2012; Donahue R. et al 2010]. Not all humans have enough of the essential enzyme necessary to break apart the fructose polymers. The remaining fructans continue on to the large bowel, where they are fermented with the naturally occurring bacterial flora. As they ferment, the fructans may also pull in large amounts of water into the colon, which can cause bloating and diarrhea [Muir JG et al 2007].

How can fructan intolerance be tested?

There is no Standardized Test for a diagnosis of fructan intolerance but Breath Testing is a Possibility. The breath tests that measure the content of hydrogen (H2) and methane (CH4) levels produced at different time intervals. The test involves providing a certain dose of fructans for consumption before test. Breath samples were collected and assessed for H2 and CH4 level every 30 min for 5 hours. Moreover, abdominal symptoms that may occur during testing are also used to determine intolerance. The Fructan Intolerance Index is a change of level H2 and CH4 over the baseline along with abdominal symptoms during the test. It was found that breath test may best characterize fructan intolerance

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