Fructan: The Real Culprit Behind Gluten Sensitivity

Written by Annalise May
Posted November 29, 2018

Do you routinely suffer with bloating, abdominal pain, diarrhea, constipation, and fatigue?

You may be wondering if you have a gluten sensitivity.

While these are the most common symptoms of gluten intolerance, you may not have to give up your favorite gluten-filled foods just yet.

New research shows that it could actually be fructan that your digestive system is not tolerating.

Fructan is a type of carbohydrate found naturally in wheat, fruits, and vegetables and added into processed foods. It is a substance not digestible in the small intestine of humans.1

These carbohydrates, present in many of the same foods as gluten, can cause gastrointestinal upset in some individuals, similar to the presentation of gluten sensitivity.

Could this sneaky carbohydrate be lurking in your diet?

What is Fructan?

Fiber Rich Foods

Fructan, a type of carbohydrate comprised of fructose molecules, is present in more of the foods you eat than you may realize.

Humans do not have the digestive enzyme necessary to break down the fructan carbs properly in the small intestine. Instead, they are fermented by good bacteria in your gut, causing malabsorption.2

While some people have no problem tolerating fructan, others are at the mercy of this secret source of inulin fiber for their digestive health.

Inulin fiber, a type of fiber extracted from enriched plants such as chicory root and Jerusalem artichoke, is known to cause gas and bloating in those who do not tolerate it well. Individuals with digestive diseases such as irritable bowel syndrome have been found to benefit from removing all sources of fructan and inulin fiber from their diet.3

Fructan is found naturally in asparagus, barley, garlic, onion, rye, white bread, wheat flour, and wheat pasta. It is also manufactured into processed foods such as protein powders, protein bars, and cereals to increase the fiber content of the product.

Many health benefits come with the consumption of soluble fiber such as fructan. High fiber intake is associated with protecting against serious conditions such as coronary heart disease, diabetes, obesity, high blood pressure, and some gastrointestinal disorders.4

In addition, high fiber diets help improve constipation and sensitivity to fullness and satiety.5 When you feel full and satisfied, you are less likely to overeat and therefore will lose weight naturally through appetite control.

Along with these benefits, eating a sufficient amount of fiber helps improve the health of your gut’s microbiome, which has widespread health effects throughout the body, from reducing inflammation to improving your immune system.6

While most individuals are encouraged to add as much fiber to their diet as possible to reap these benefits, fructan is often present in high-fiber foods. If you have an intolerance to fructan and eat a fiber-enriched food such as a protein bar, the first symptoms you may experience are bloating, abdominal pain, diarrhea, and constipation.

In order to keep the benefits of fiber in your diet, eat fructan-free fruits and vegetables. Getting your fiber from a natural source, such as the skin of a raw fruit, is the best way to regulate your gut health with fiber. Artificial supplements containing fiber could be more harmful than helpful to your gut.  

Is it an Intolerance or an Allergy?

Inulin Molecule

Before making any changes to your diet, it is necessary to examine all the possible causes of your digestive discomfort. Fructan sensitivity can mimic the symptoms of many other conditions.

It is important to note the difference between fructan intolerance and a fructose allergy. Fructan is a type of carbohydrate made up of fructose molecules strung together. In other words, fructans are made up of fructose, or simple sugar molecules.7 Fructose is a simple sugar found in sweeteners, fruits, some vegetables, table sugar, and other sweet foods.

You may be wondering what the difference is between a food intolerance and a food allergy. An allergy is when the immune system overreacts to the proteins in a certain food. This can cause a range of symptoms throughout the body, in some cases a life-threatening reaction.

A food intolerance is generally less serious and is usually limited to digestive problems. With a food intolerance, you may be able to eat small amounts of a certain food without symptoms. A food allergy will always produce a body-wide reaction due to immune system dysfunction.8,9

A fructan intolerance and a fructose allergy have similar symptoms, but the difference is the sources in which they are found. Fructose, a sugar high on the glycemic index, is found in honey, agave nectar, dried fruits, juices, and foods containing high fructose corn syrup, such as soft drinks and processed, pre-packaged foods. As mentioned earlier, fructan is found in certain types of vegetables, grains, and processed foods.

Another condition to rule out if you suffer with consistent gastrointestinal upset is small intestinal bacterial overgrowth (SIBO). This condition is defined as the excessive presence of bacteria in the small intestine. While originally thought of as a rare condition, this disorder, which most often presents as chronic diarrhea, malabsorption of nutrients, and unexplained weight loss, is becoming more common.10

The mechanism behind fructan intolerance is different than an allergy or SIBO. While in other conditions the imbalance of good and bad gut bacteria causes uncomfortable symptoms, a fructan intolerance is the body’s inability to digest fructan.

Is it Fructan or Gluten?

Frcutose Molecule

Now that you know the difference between a food allergy and a food intolerance, it’s time to sort through the biggest confusion of all: Is it fructan intolerance or gluten intolerance?

In recent years, the avoidance of gluten-containing and wheat products has become a worldwide phenomenon. You could even call it a fad. While celiac disease — a well-recognized medical condition in which the body’s immune response to gluten causes inflammation and damage to the small intestine — can be diagnosed by a doctor, a gluten “sensitivity” or a wheat intolerance is a relatively new self-diagnosed condition.11

Non-celiac gluten sensitivity (NCGS), where intestinal symptoms appear in the absence of a celiac disease or wheat allergy diagnosis, tends to be how individuals self-diagnose when they experience painful bloating, abdominal distention, gas, diarrhea, and other discomfort.

Most people think they need to follow a gluten-free diet in order to eliminate these symptoms. Even doctors or nutritionists may advise their patients to eliminate wheat and gluten without realizing what the real culprit could be.

It is not simple to distinguish between these two conditions. There is currently no medical testing to diagnose a fructan or gluten sensitivity or intolerance. Fructan is not usually the first go-to hypothesis in the medical community. Many professionals are not familiar with this digestive irritant.

However, recent research reveals the potential for fructan intolerance to be the cause of symptoms similar to NCGS.

A report recently published in Gastroenterology reveals that fructan can cause similar symptoms to a self-reported gluten sensitivity.

This randomized, double-blind, placebo-controlled study examined 59 individuals on a self-induced gluten-free diet for whom a celiac disease diagnosis had been excluded.

The participants were randomly assigned to diets containing gluten, fructan, or a placebo for a period of seven days. Using the Gastrointestinal Symptom Rating Scale, their symptoms were measured.

The results revealed that those who ate fructan scored higher on the Gastrointestinal Symptom Rating Scale than those eating a gluten or placebo diet.

The fructan diet was the only one to induce stomach pain and bloating.12

Signs of Suffering

Fiber Rich Foods

While conditions such as fructan sensitivity and intolerance are relatively common, they look like so many other conditions that it can be difficult to recognize, treat, and manage them.

Receiving a breath test from your doctor is one of the most common ways to receive a diagnosis. This test measures the small amount of gases that are produced after you consume even a small amount of fructans.

You should reach out to your doctor and get tested as soon as possible if you’ve been consistently suffering with gastrointestinal issues. You may be suffering with a fructan intolerance if you experience the following symptoms:

  • Abdominal pain
  • Bloating
  • Excessive gas
  • Stomach cramps
  • Nausea
  • Constipation
  • Diarrhea
  • Fatigue

The next step to heal these symptoms is to reduce your intake of fructans. A foolproof way to determine if you have a sensitivity to foods high in fructans is to follow a fructan elimination diet.

Consult with your doctor before you make any major changes in your diet or health routine.

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High-Fructan Foods to Avoid

Gltuen Free

By changing your diet, you can remedy your fructan intolerance at home and start feeling better. In order to find relief, use this high-fructan food list as a guide for what to limit if you have a fructan intolerance.

The most common high-fructan foods are:


  • Watermelon
  • Bananas
  • Nectarines
  • Grapefruit
  • White Peaches


  • Brussels sprouts
  • Cabbage
  • Broccoli
  • Artichoke
  • Fennel
  • Garlic
  • Leeks
  • Peas
  • Shallots
  • Onions


  • Rye
  • Barley
  • Wheat
  • Spelt


  • Pistachios
  • Cashews
  • Almonds


  • Soybeans
  • Dried beans
  • Dried lentils
  • Dried chickpeas


  • Chamomile tea
  • Instant coffee
  • Chicory coffee
  • Fiber-enriched foods
  • Foods containing inulin fiber13


If the list of foods to avoid feels overwhelming, another helpful guide to follow is a low FODMAP diet. FODMAP stands for the group of short-chain carbohydrates: fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. Fructose and fructans are both a part of FODMAP.

Recent research reveals that following a low FODMAP diet has been found to heal symptoms in patients with different unexplained gastrointestinal symptoms as well as those diagnosed with irritable bowel syndrome.14

A low FODMAP diet focuses on limiting the consumption of troublesome carbs and increasing the consumption of foods that are easily digestible.

Following a low FODMAP diet is a great short-term solution to figure out if you’re suffering with any food intolerances. While you’re eating a low FODMAP diet, first all high FODMAP foods are eliminated. After a period of several weeks or when your gastrointestinal symptoms decrease, you can begin to slowly introduce different foods one at a time in order to assess them for tolerance.

High FODMAP Foods to Avoid:


  • Wheat including bread, pasta, and couscous
  • Onions
  • Shallots
  • Scallions
  • Garlic
  • Barley
  • Brussels sprouts
  • Cabbage
  • Broccoli
  • Pistachio
  • Artichoke
  • Inulin or chicory root


  • Soy milk
  • Soy protein isolate
  • Miso
  • Veggie burgers
  • Dried beans and peas
  • Lentils
  • Butter/lima beans
  • Hummus
  • Large amount (more than one cup per day) of coffee


  • Soft cheeses including ricotta, cottage, and cream cheese
  • Milk
  • Cream
  • Yogurt
  • Butter
  • Ice cream


  • Artificial sweeteners (xylitol, sorbitol, etc.)
  • Apples
  • Plums
  • Cherries
  • Pears
  • Cauliflower
  • Sweet corn
  • Snow peas
  • Mushrooms15

Low FODMAP Foods to Incorporate:


  • Oranges
  • Unsweetened cranberries
  • Strawberries
  • Cantaloupe
  • Lemon
  • Lime
  • Blueberries
  • Clementines
  • Grapes
  • Guava
  • Kiwi
  • Oranges
  • Passion fruit
  • Papaya
  • Raspberries
  • Tamarind fruit


  • Peas
  • Celery
  • Carrots
  • Plum tomato
  • Spinach
  • Lettuce
  • Green peppers
  • Green beans
  • Bean sprouts
  • Turnip
  • Cucumber
  • Avocados
  • Cauliflower
  • Eggplant
  • Mushrooms
  • Olives
  • Potatoes
  • Pumpkin
  • Swiss chard
  • Spinach
  • Rutabaga
  • Sweet potatoes
  • Watercress
  • Yams
  • Zucchini


  • Hard cheeses (cheddar, Swiss, parmesan)
  • Lactose-free unsweetened yogurt
  • Lactose-free milk

Meats/meat alternatives

  • All plain unprocessed meats
  • Beef
  • Chicken
  • Fresh fish
  • Lamb
  • Turkey
  • Tofu
  • Eggs
  • Tempeh


  • Arrowroot
  • Buckwheat
  • Millet
  • Oats
  • Rice
  • Sorghum
  • Gluten and rye-free bread
  • Corn
  • Grits


  • Walnuts
  • Peanuts
  • Macadamia nuts
  • Chia seeds
  • Pumpkin seeds
  • High-fructose corn syrup-free peanut butter
  • Almonds


  • Canned chickpeas
  • Canned beans
  • Canned lentils


  • Regular tea
  • Regular coffee
  • Buckwheat or quinoa cereals
  • Corn tortilla
  • Plain popcorn
  • Oat rice16

By following these guidelines, you can take control of your health and start to heal gastrointestinal upset. However, it is important to use caution whenever making changes to your diet.

Because fructans occur naturally in some nutrient-dense foods such as fruit, vegetables, and whole grains, it is imperative not to cut them out completely. Try low FODMAP alternatives instead in order to avoid vitamin or nutrient deficiencies. For example, you can easily switch out cabbage for cauliflower or grapefruit for clementines.

If fructans are the culprit of your digestive issues, we hope that by starting with these guidelines and information, you can begin to heal your gut.

To your health,


Annalise May
Contributing Editor, Clear Health Now


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