Fructan Intolerance vs. Gluten Sensitivity: What You Need to Know

There is a lot of chatter today about FODMAPs and fructans, and many people are now wondering if they have a fructan intolerance rather than a gluten intolerance. In this post, I define fructan intolerance, discuss why gluten intolerance and fructan intolerance often become confused, and explain how you can figure out exactly what is ailing you most. Please read my disclaimers.

Many people with self-diagnosed gluten sensitivity might actually have a fructan intolerance instead, according to research published in Gastroenterology in 2018.¹

Researchers found, in a randomized, double-blind, placebo-controlled crossover study of individuals with self-reported non-celiac gluten sensitivity, that fructans induced bloating and other gastrointestinal symptoms as measured by the Gastrointestinal Symptom Rating Scale (GSRS-IBS).¹

What Are Fructans?

Before we get more into the details of the study, let’s discuss fructans first.

A fructan is a type of carbohydrate found in wheat and a variety of fruits and vegetables. Fructans are oligosaccharides or polysaccharides that consist of short chains of fructose units.² Fructans comprise the “O” in FODMAPs, which stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols.³

What you need to know is that humans lack the digestive enzymes (fructan hydrolases) needed to break down these oligosaccharides.⁴ As a result, humans only absorb 5 to 15 percent of the fructans they consume.⁵ The rest is carted off to the colon to be naturally fermented by gut bacteria, which can lead to gas, bloating, and other digestive woes in some people, particularly those with irritable bowel syndrome (IBS) or visceral hypersensitivity.⁴

What Foods Contain Fructans?

Fructans are most commonly found in products containing or made from wheat, such as breads, pasta, and couscous. They are also found in certain vegetables, fruits, legumes, and nuts. Here is a list of high-fructan foods to avoid or limit if you suspect a fructan intolerance:⁶

Breads / Grains: Wheat, barley, rye, spelt, kamut

Vegetables: Artichokes (globe and Jerusalem), asparagus, Brussels sprouts, savoy cabbage, fennel, garlic, leeks (bulb), onions (including shallots and spring onion bulbs), snow peas

Fruits: Grapefruit, nectarines, ripe bananas, watermelon, peaches, persimmons, plums, pomegranates, dried fruits (dates, prunes, raisins)

Nuts: Cashews, pistachios

Legumes: Chickpeas (dried / large servings), lentils (dried / large servings), kidney beans, baked beans, soybeans

Other: Inulin (chicory root extract), some herbal teas (chamomile, oolong)

Note: Serving sizes matter on a low-FODMAP diet. For example, small amounts of canned lentils or chickpeas may be tolerated, while larger amounts or dried versions are high in fructans and galacto-oligosaccharides (GOS).⁶

What Did Researchers Find?

Researchers at Oslo University Hospital in Norway conducted a double-blind crossover challenge for 59 individuals on a self-instituted gluten-free diet. Researchers ruled out and excluded participants with celiac disease.¹

Participants were randomly assigned to groups placed on a seven-day diet containing one of the following ingredients, concealed in muesli bars:

• Gluten (5.7 g)
• Fructans (2.1 g)
• Placebo

Participants waited a minimum of seven days after their first eating challenge (until symptoms resolved), and then crossed over into another group until they completed all three challenges. Their symptoms were measured using the Gastrointestinal Symptom Rating Scale for irritable bowel syndrome (GSRS-IBS).¹

Researchers found a significant difference in how each challenge affected the participants. Here’s what they found:

• 13 participants experienced the highest gastrointestinal symptom score after consuming gluten.
• 24 participants had the highest score after consuming fructans.
• 22 participants had the highest score after consuming the placebo.

Moreover, researchers found that there was no significant difference in overall GSRS-IBS scores between the gluten and placebo groups.¹

This study suggests that fructans, more so than gluten, are likely to induce symptoms in people with self-reported non-celiac gluten sensitivity. It suggests that those without a diagnosed gluten sensitivity or celiac disease may find relief from their symptoms by avoiding fructans rather than only gluten.¹ ⁷

Should a Fructan Intolerance Be Treated with a Gluten-Free Diet?

While fructans and gluten co-exist in many foods (like wheat, barley, and rye), a better protocol for someone with a fructan intolerance might be to avoid fructans specifically, not just gluten.

That said, many gluten-free grains — like rice, quinoa, and oats — are low in FODMAPs and safe for those avoiding fructans. This is why a gluten-free diet often offers accidental relief to someone with a fructan intolerance: by cutting out wheat, they are inadvertently cutting out a major source of fructans.⁴

Remember, if you’re switching from a gluten-free diet to a low-FODMAP diet, you still need to avoid high-fructan grains like wheat, rye, and barley.

However, you might be able to enjoy something like traditional sourdough bread. The long fermentation process used to make authentic sourdough allows the yeast and bacteria to consume and break down much of the fructans, making it a lower-FODMAP food that is easier to digest.⁸ Keep in mind that not all commercial sourdoughs are long-fermented, so look for traditionally made varieties.

Also, small amounts of wheat bran — up to ½ tablespoon — are considered low-FODMAP and may be tolerated on a fructan elimination diet, though larger amounts become high in fructans.⁹

Please note that if you have celiac disease or a diagnosed wheat allergy, you must continue to eat a strict 100 percent gluten-free diet, as sourdough and wheat bran still contain gluten.

If you are unsure whether you suffer from gluten sensitivity, celiac disease, or fructan intolerance — or perhaps a combination — please consult your doctor or a registered dietitian to get properly tested and to safely transition your diet.

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References

1. Skodje, G. I., et al. (2018). Fructan, Rather Than Gluten, Induces Symptoms in Patients With Self-Reported Non-Celiac Gluten Sensitivity. Gastroenterology, 154(3), 529–539.e2. https://doi.org/10.1053/j.gastro.2017.10.040
2. Fructan. Wikipedia. https://en.wikipedia.org/wiki/Fructan
3. Cleveland Clinic. (2022). Low FODMAP Diet: What It Is, Uses & How to Follow. https://my.clevelandclinic.org/health/treatments/22466-low-fodmap-diet
4. Glinski, S. (2026). High Fructan Foods: What They Are, Symptoms & What to Avoid. Fodzyme. https://fodzyme.com/blogs/resources/high-fructan-foods
5. Fedewa, A., & Rao, S. S. (2014). Dietary fructose intolerance, fructan intolerance and FODMAPs. Current Gastroenterology Reports, 16(1), 370. https://pmc.ncbi.nlm.nih.gov/articles/PMC3934501/
6. Monash University. High and Low FODMAP Foods. https://www.monashfodmap.com/about-fodmap-and-ibs/high-and-low-fodmap-foods/
7. Dietitians On Demand. (2025). Fructan vs. Gluten Intolerance. https://dietitiansondemand.com/fructans-vs-gluten/
8. Monash University. (2017). Sourdough Processing & FODMAPs. https://www.monashfodmap.com/blog/sourdough-processing-fodmaps/
9. A Little Bit Yummy. (2018). Can You Eat Wheat on the Low FODMAP Diet? https://alittlebityummy.com/blog/can-you-eat-wheat-on-the-low-fodmap-diet/