What Are Fructans? Signs of Fructan Intolerance & How to Overcome It

April 18, 2018

Found in abundance throughout the food supply — both in natural food sources and added into processed foods — most of us get a hearty dose of fructans in our daily diets without even realizing it. Not only is fructan plentiful in grains and wheat products, but it’s also present in many types of fruits, vegetables and even beverages that you may be consuming on a daily basis.

While most of us have no problem at all tolerating this sneaky source of inulin fiber, it has been known to wreak havoc on the digestive health of many. Some research has also found that it may be a hidden culprit of certain food intolerances and persistent gastrointestinal troubles. Plus, other studies suggest that many people who may think they have a sensitivity to gluten may actually have a fructan intolerance instead.

If you suffer from constant bloating, gas or abdominal pain, cutting back on your fructan intake is something you may want to consider. Here’s what you need to know about this tricky type of carbohydrate and where it may be lurking in your diet.

What Are Fructans?

The official fructans definition is “a type of polymer of fructose molecules found in certain fruits.” Putting aside the scientific jargon, though, fructans are simply a type of carbohydrate made by a chain of fructose molecules strung together.

Fructans can be found in many types of fruits and vegetables, such as onions, artichokes, garlic and ripe bananas, as well as several different kinds of cereal and grains. Food manufacturers also sometimes add fructans to foods to increase the fiber content of their products.

Because humans don’t have the fructan digestive enzyme, fructans cannot be effectively digested in the small intestine like other nutrients. Instead, they are fermented by the beneficial bacteria in your gut. (1)

There have been a number of health benefits associated with soluble sources of fiber like fructans. A high intake of fiber may help protect against conditions like coronary heart disease, high blood pressure, diabetes, obesity and even some gastrointestinal disorders. (2)

Fiber can also help promote regularity and prevent constipation, plus support satiety and keep your appetite under control to aid in weight loss. (3, 4) Not only that, but it also helps improve the health of your gut microbiome, which is associated with everything from enhanced immunity to reduced inflammation. (5)

However, despite the impressive array of health benefits attributed to fiber, certain types of fiber like fructans may have an adverse effect on health as well.

In fact, although some people may tolerate fructan-frich foods just fine, they can trigger some serious gastrointestinal issues in others. Bloating, diarrhea, pain and constipation can be common symptoms of an intolerance to fructans.

Note that fructan intolerance is not the same as fructose malabsorption or a fructose “allergy.” This is caused by a reaction to the units that make up fructans, which are a form of simple sugars known as fructose. Although they can cause similar symptoms, the main difference between fructan vs. fructose is that fructose is found primarily in fruits, fruit juices, agave nectar, honey, molasses, table sugar and high fructose corn syrup, while fructans are found in certain types of grains, vegetables and processed foods.

It’s also important to remember that a sensitivity to fructans is not the same as small bacterial overgrowth, or SIBO. This is a condition characterized by an excessive amount of bacteria in the small intestine, which can cause issues like diarrhea and malabsorption if left untreated. With a fructan intolerance, the main problem isn’t your gut bacteria, but the way that your body handles fructans.

Fructans vs. Gluten

While fructans are a type of carbohydrate, gluten is actually type of protein found in many cereal grains and wheat products. For those with celiac disease or a sensitivity gluten, eating gluten can cause a slew of negative gluten intolerance symptoms, such as diarrhea, fatigue, gas and even bone loss.

However, emerging new research has recently found that many gluten sensitivity symptoms may actually be caused by impaired fructans digestion instead. This is because fructans are also found in many gluten foods and can cause symptoms that are similar to those triggered by a gluten allergy.

Gluten sensitivity, in particular, is a condition that is especially difficult to officially diagnose. Many people with a sensitivity to gluten find that they feel better when cutting out gluten-containing foods from their diets, but it’s unclear if this may be due to the elimination of gluten or a reduced intake of other ingredients, such as fructans.

Interestingly, a recent 2018 study published in the journal Gastroenterology looked at 59 people without celiac disease who were following a gluten-free diet. They were randomly assigned to receive a bar containing either gluten, fructans or a placebo for seven days before switching groups. At the end of the study, they actually found that consuming fructans resulted in more symptoms of irritable bowel syndrome, such as gas, bloating, abdominal pain and bowel changes, than gluten, indicating that cutting back on fructans may be the key to gastrointestinal relief for those with a gluten sensitivity. (6)

Signs of Fructan Intolerance

Conditions like fructan and fructose intolerance are relatively common, but they can be difficult to recognize and manage. Breath tests are the most common tool used for diagnosis, which work by measuring the production of gases produced following the consumption of a small amount of fructans.

Properly identifying your symptoms can also aid in diagnosis. An intolerance to fructans can cause many symptoms, which may include:

Gas
Bloating
Stomach pain
Constipation
Diarrhea
Abdominal discomfort
Nausea
Cramps

If you suffer from these symptoms, reducing your intake of fructans. Trying out a fructan elimination diet can also help determine if you may have a sensitivity to foods high in fructans.

High-Fructan Foods to Avoid

Switching up your diet is the best fructan intolerance remedy. By eliminating fructans foods from your diet, you can start to sidestep unpleasant gastrointestinal symptoms and help find relief.

Use this fructans list as a guide for which foods you should limit if you have an intolerance to fructans. A few of the most common high-fructan foods include:

Breads/Grains:

Barley
Rye
Wheat
Spelt

Vegetables:

Artichokes
Brussels Sprouts
Cabbage
Fennel
Garlic
Leeks
Onions
Peas
Shallots

Fruits:

Grapefruit
Nectarines
Persimmon Fruit
Ripe Bananas
Watermelon
White Peaches

Nuts/Seeds:

Almonds
Cashews
Pistachios

Legumes:

Chickpeas (dried)
Lentils (dried)
Beans (dried)
Soybeans

Other:

Instant Coffee
Chicory Coffee
Chamomile Tea
Fiber-enriched foods or foods containing inulin

Low-Fructan Foods and Low-FODMAP Diet to Follow

FODMAPs, which is short for “fermentable oligo-, di-, mono-saccharides and polyols,” are a type of short-chain carbohydrate that is poorly absorbed by the body. The fructose that makes up fructans is one type of FODMAP, along with other carbohydrates, such as lactose and sugar alcohols.

The FODMAP diet focuses on limiting consumption of foods high in these short-chain carbs and emphasizing the consumption of foods that are easily digested instead.

The FODMAP diet can also be used as a short-term solution to help figure out which foods you may be sensitive to. During the initial period of the diet, all high-FODMAP foods are eliminated completely. After several weeks, they can be slowly reintroduced one at a time and assessed for tolerance.

Although the list of fructan foods is pretty extensive, there are plenty of options that you can still enjoy on a low-FODMAP diet plan. Here are some nutrient-rich options that you can easily incorporate into your diet:

Meat/Poultry/Seafood:

Beef
Canned tuna fish
Chicken
Fresh Fish
Lamb
Turkey

Breads/Grains:

Arrowroot
Buckwheat
Millet
Oats
Quinoa
Rice
Sorghum

Vegetables:

Avocados
Bell Peppers
Cauliflower
Celery
Carrots
Cucumber
Eggplant
Lettuce
Mushrooms
Olives
Potatoes
Pumpkin
Swiss Chard
Spinach
Rutabaga
Sweet Potatoes
Watercress
Yams
Zucchini

Fruits:

Blueberries
Cantaloupe
Clementines
Grapes
Guava
Kiwi
Lemon
Lime
Mandarin Oranges
Oranges
Passion Fruit
Papaya
Raspberries
Strawberries
Tamarind Fruit

Nuts/Seeds:

Walnuts
Pumpkin Seeds
Chia Seeds
Macadamia Nuts
Peanuts

Legumes:

Chickpeas (canned)
Beans (canned)
Lentils (canned)
Tempeh

Other:

Regular Tea
Regular Coffee

Recipes to Combat Fructan Intolerance

Just one look at a FODMAP diet chart could scare just about anyone out of trying a low-FODMAP diet. Fortunately, however, there are tons of tasty, FODMAP-friendly foods and recipes out there that are low in fructans to help minimize your symptoms.

You can also make some easy swaps in your diet to make it even easier to cut down on your fructan intake. Here are a few simple switches that you can try out:

Trade in your morning slice of toast for a bowl low-fructan oats instead.
Enjoy a soothing cup of black, white or green tea instead of chamomile tea.
Instead of dried beans or lentils, use canned varieties. The liquid in canned foods leaches out the fructans, resulting in a lower content of FODMAPs. You can also try fermented foods like tempeh or natto, which are also low in fructans.
Use arrowroot flour instead of white flour to thicken soups and stews, whip up delicious puddings and act as a binder for recipes like meatloaf or veggie burgers.
In place of garlic and onions, try seasoning your foods with the tops of scallions, garlic-infused oils, or healthy herbs and spices like cumin, paprika, basil or rosemary.
Finally, if you’re looking for a fructan-free bread, give sourdough a try. While not entirely free of fructans, one study found that it may contain up to 90 percent fewer FODMAPs than regular bread. (7)

Need some more inspiration? Here are a few delicious, low-fructan recipes to get you started:

History

There are two types of fructans found throughout nature. Those composed of shorter chains of fructose units are called fructo-oligosaccharides, often abbreviated as FOS. Longer chains with at least 10 units of fructose molecules, on the other hand, are known as inulin.

Inulin is found in more than 36,000 species of plants and is used to store energy in vegetables like onions, artichokes and asparagus. It was originally discovered in 1804 by a scientist named Valentin Rose, who discovered it while boiling the roots of an herb called Inula helenium, also known as elecampane.

Today, inulin is often used by food manufacturers to bump up the fiber content of foods. It’s a common ingredient in high-fiber bars, cereals and meal replacements and can also be found in a variety of other ultra-processed foods as well. It’s sometimes listed under other names like chicory extract and chicory root.

Precautions

Note that not everyone is sensitive to fructans, and soluble types of fiber like fructans have actually been associated with a wide range of beneficial effects on health. If you don’t experience gastrointestinal symptoms after eating fructan-rich foods, you can still enjoy these nutritious fruits and veggies as part of a balanced diet.

If you do suffer from irritable bowel syndrome or non-celiac gluten sensitivity, however, cutting fructans out of your diet and seeing if symptoms persist may be beneficial. If you have been diagnosed with celiac disease or wheat allergy symptoms, keep in mind that you should also be sure to keep gluten out of your diet as well.

Additionally, although there have been some studies showing a connection between fructans and IBS symptoms, other foods on the FODMAP chart can also contribute to symptoms. If you eliminate fructans from your diet but still experience persistent bloating, gas or diarrhea, you may want to consider trying out a FODMAP elimination diet to determine if other types of short-chain carbohydrates may also be triggering these side effects.

Because fructans are often found in nutrient-dense foods, such as fruits, vegetables and whole grains, it’s important to avoid eliminating these entire food groups altogether. Instead, include low-fructan foods from these food groups to get in the important vitamins and minerals that you need. You can easily swap out cabbage for Swiss chard or enjoy oranges instead of nectarines to make sure you’re meeting your micronutrient requirements.

Final Thoughts

What is fructan? Fructan is a type of carbohydrate made up of fructose molecules that is found in many types of food.
Humans cannot digest fructans, so they are instead fermented by the bacteria in the gut. While this can provide health benefits to some, it may cause gastrointestinal distress in others.
Studies show that some gluten allergy symptoms may actually be caused by fructan malabsorption.
Research also shows a link between fructans and stomach pain, bloating, gas, constipation and diarrhea.
Fructans are in foods like wheat, barley and rye, as well as several different types of fruits and vegetables. They are also sometimes added to processed foods to increase the fiber content as well.
If you think you may suffer from a sensitivity to fructans, limiting your intake of fructans or trying out a FODMAP diet may be useful.