Fructose Malabsorption: A Beginner’s Guide to Treatment

Fructose Malabsorption- A Beginner's Guide

[Last updated 10th February, 2018]

Fructose malabsorption is a gastrointestinal condition that causes digestive discomfort.

It’s common in sufferers of Irritable Bowel Syndrome (IBS), but can also be experienced in others.

This article looks in detail at fructose malabsorption and explores the scientifically-proven diet changes that can help improve your symptoms.

What is Fructose and Fructose Malabsorption?  

What is Fructose and Fructose Malabsorption? Fructose is a simple carbohydrate, or single sugar, found in many plants.

It’s the major sugar found in fruit, which is why it’s sometimes referred to as ‘fruit sugar’. However, it also occurs naturally in honey, wheat and some vegetables.

Fructose can be found in three ways:

  • As free fructose.
  • Bonded to glucose to form table sugar.
  • As part of a fructan. Fructans are multiple fructose molecules joined to one glucose molecule.

When fructose is eaten, it travels to the small intestine where it is absorbed without needing help from digestive enzymes.

Fructose Malabsorption

In fructose malabsorption, the left over fructose travels to the colon and takes lots of water with it (called an osmotic effect).

Fructose is then fermented by gut bacteria in the colon (large intestine). This fermentation produces short chain fatty acids and the gases hydrogen, methane and carbon dioxide (1).

what is fructose malabsorption

Image source. Click to enlarge.

Fructans are slightly different. They always travel straight to the colon where they are quickly fermented by bacteria. When fructans and other fructose are eaten together it may make symptoms worse (2).

Summary: Fructose is a carbohydrate found in many plants. Fructose malabsorption causes fructose to move into the colon where it is fermented by bacteria, producing short chain fatty acids and gas.

Fructose Malabsorption or Fructose Intolerance? 

Fructose Malabsorption or Fructose Intolerance? You may hear fructose malabsorption and fructose intolerance used interchangeably, but they may not refer to the same thing.

Fructose intolerance or hereditary fructose intolerance (HFI) is a genetic condition caused by deficiency of an enzyme that breaks down fructose in the liver. HFI is usually diagnosed at a young age, when babies start to eat food or have formula containing fructose (3, 4).

HFI can cause serious liver problems if left unmanaged. Fortunately, like fructose malabsorption, it can be effectively managed with diet changes (5).

Fructose malabsorption is not necessarily genetic, unlike HFI.

Summary: Fructose malabsorption should not be confused with hereditary fructose intolerance. Hereditary fructose intolerance is a genetic condition that prevents the break down of fructose and can cause liver problems.

Signs and Symptoms of Fructose Malabsorption 

Signs and Symptoms of Fructose Malabsorption Sufferers of fructose malabsorption often experience similar symptoms to those caused by IBS

The combination of extra water and gas in the colon is what causes uncomfortable digestive complaints.   

Common symptoms include (2, 4, 6):

Summary: Symptoms of fructose malabsorption are caused by extra water and gas in the colon. Symptoms include abdominal pain, nausea and diarrhea.

Testing for Fructose Malabsorption 

Fructose malabsorption can be diagnosed using a hydrogen breath test (7).

Most of the gas produced by bacteria in the colon moves into the bloodstream and then into the lungs. We then breathe this gas out. The hydrogen breath test measures the amount of hydrogen in our breath (7).

fructose malabsorption hydrogen breath test

Flow chart for breath testing protocol. Image source. Click to enlarge.

Some people may complete a slightly different test because they naturally don’t produce enough hydrogen gas. In this case, methane gas is usually measured instead (8).

Although the hydrogen breath test is commonly used for diagnosis, some people still experience positive results from diet changes, even when their breath test didn’t show fructose malabsorption (9). 

Summary: A hydrogen breath test can be used to diagnose fructose malabsorption.

Diet Changes for Fructose Malabsorption 

Eliminating fructose completely from you diet is near impossible.

The main aim is to determine how much you can tolerate without causing uncomfortable digestive issues. Each person is unique.

A low FODMAP diet

What is low FODMAP and who is it for?A low FODMAP diet is a science-based strategy to determine how much fructose you can tolerate.

People with fructose malabsorption also tend to be sensitive to other FODMAPs too.

FODMAPs are a group of short-chain carbohydrates, like fructose and fructans, which can cause digestive issues when they are poorly absorbed. 

The diet involves an elimination phase where you restrict or exclude all FODMAPs for 3-8 weeks. This gives your gut some time to heal and the good gut bacteria time to thrive.

Next, each FODMAP is reintroduced or challenged one at a time. The aim is to learn which FODMAPs you can tolerate and how much of each FODMAP you can eat without having symptoms.

The low FODMAP diet can be quite complicated and difficult to do correctly on your own. I would recommend seeking help from a FODMAP-trained dietitian where possible to achieve the best result.

Balance Your Glucose to Fructose Ratio

Glucose is the other main sugar molecule alongside fructose, but they are metabolized differently.

Dr. Sue Shepard and Dr. Peter Gibson, pioneers of the low FODMAP diet, discovered that foods containing as much or more glucose than fructose are better tolerated.

In other words, it helps to eat as much or more glucose than fructose in those who are sensitive (2).

It seems as long as glucose is consumed in a 1:1 ratio with fructose (or greater), the co-transport system will help with fructose absorption in the small intestine (up to a point, it can be overwhelmed) (1, 3).

It’s one of the reasons why foods with excess fructose compared with glucose, such as apples, pears, and mangoes, will likely trigger abdominal symptoms.

Dr. Shepard and Dr. Gibson produced this handy table outlining unfavourable and favourable foods to help make these diet changes.

fructose to glucose ratio for low fodmap and IBS

Favourable vs unfavourable foods related to fructose content. Image source. Click to enlarge.

Summary: A low FODMAP diet can be used to work out if fructose is your only problem and how much fructose you can tolerate. Eating glucose at the same time as fructose can help increase absorption. A registered dietitian can help you create an individualised plan.

Can Supplements Help?

Xylose isomerase

Can Supplements Help?Xylose isomerase is an enzyme that converts fructose to glucose in the small intestine (10).

Taken as a supplement, it may improve symptoms of fructose malabsorption (4, 10).

In a study of 65 patients with fructose malabsorption, patients randomly received a pill containing the enzyme or a placebo. Those that used the enzyme saw significant improvements in abdominal pain and nausea, but not bloating, compared to those that took the placebo (10).

xylose isomerase for fructose malabsorption and low fodmap

XI = xylose isomerase supplement.

However, patients only had fructose in a water solution. It’s unclear whether the enzyme would act differently, or as effectively, when fructose is eaten as part of a meal.

Other Supplements

Other than xylose isomerase, supplements that help manage overall IBS may also be helpful for fructose malabsorption.

In particular one type of fiber supplement, and potentially probiotics too

Summary: Xylose isomerase is an enzyme that may reduce fructose malabsorption when taken as a supplement. But much more research is needed.

The Punch Line

Fructose malabsorption is a common condition that is treated with diet changes.

The most important step is to work out how much fructose you can tolerate and how to balance your diet.

A registered dietitian can work with you using a low FODMAP diet and other scientifically tested strategies to eliminate symptoms.

Fructose malabsorption is a gastrointestinal condition common in those with Irritable Bowel Syndrome (IBS). This article explores how to manage symptoms.


  1. I’m glad this is a thing. I thought I was being hypochondriacal when apples, pears and bananas started hurting my stomach. Tangerines don’t bother me at all, but it seems anything else with a peel (even though I don’t eat the peel) hurts my stomach. Good to know I’m not imagining things.

  2. It would be interesting to know how many people with fructose issues also suffer from eczema or other forms of skin problems. Please leave a comment describing your skin symptoms if you are one of those people. Thank you.

    • Not sure if skin condition is related to FM. But whenever I eliminate gluten from my diet, I see huge improvements with my skin. Give it a try!

      • Marylea Sanders says:

        Along with FM I also have Celiac Disease and yes, I have itching and hives if I am not careful. I just read that FM can go along with Celiac.

    • When I eat high FODMAP foods I seem to get an itchy hive or two within an hour. The hives are small, but cause me to itch a 2 inch circle around them. They can be on my leg or neck or chest – different spots. The hive will disappear within a few hours. I am paying attention to these to figure out the triggers.

    • I have terrible skin reactions to FM. I am 50 years old and my face breaks out constantly. I have acne like pustules. It has been horrible as the acne is painful and embarassing. The skin issue is much worse than any of the intestinal issues, which are minor for me. I also seem to get hot flashes when I eat the high fructose foods (granted it is probably related to menopause, but they go away the less fructose I eat). I am just learning that it seems to be FM that is causing it. I have tried giving up dairy, wheat, everything. I have made my own kefir, kombucha and fermented vegetables — which made me feel even sicker! I have tried every other diet and nothing ever helped until I finally realized it could be all the apples and other fruits (smoothies especially) I have been eating every day. It is somewhat devasting to realize I do better eating french fries than I do eating pears and apples. I am giving up fruit for a while.

      • Im 53 and have had terrible acne all my life. I just get sudden flairs with deep cysts and could never figure out why. Back, chest, arms, jaw, and face. It was worst when I was vegan for ten years—just terrible. I, too, get hot flashes with a really red face when eating certain fruits but figured they couldn’t be the problem because they are healthy. Wine also causes this reaction but not other types of alcohol, although I have never tested beer. My kid has just tested with FM. I assume I have it as well. The skin symptoms are much worse than the gastrointestinal ones.

    • I had really bad cystic acne on my jaw bone, neck, shoulders, arms and back. After being on the foodmaps diet for 3 weeks everything started clearing up! When I eat something that triggers me, the acne comes back.

    • Eczema on my eyes for seven years . Thought I was crazy and allergic to everything. Today I think I just figured out it is the fructans. Because everything I seem to be allergic to happens to be a fructan.

  3. I’m fructose intolerant and have eczema but I believe it comes from dairy, as soon as I eat too much dairy the eczema flairs up, when I cut it out, the eczema is gone within days.

  4. I discovered I had fructose malabsorbtion after visiting a gastroenterologist. It started after I switched from sugar to raw honey in tea. After about a month, I would have horrible pains within an hour or so of having raw honey, and it was so bad I was laid out crying in pain for 1-2 hours. I always noticed that I avoided most fruits other than bananas, but the pain didn’t start until the raw honey. After I stopped eating raw honey and certain berries with seeds, the pains have not been back since.

    It’s interesting the distinction between malabsorbtion and intolerance, because I often wondered why my father and I had the same exact diet. He too has always had an aversion to fruit other than bananas, and would even avoid eating certain vegetables like asparagus. He associated it with taste preference, but I’m wondering if it’s a natural aversion due to an underlying genetic fructose intolerance. Furthermore, our ancestors were Scandinavian and it wasn’t natural for them to consume fruits or many ground vegetables, as it was simply too cold in that environment for most harvests. I do believe that our heritage greatly affects our diet as a vestigial trait. I encourage people to consider their ancestry and metabolic type when planning their diets.

    • For years I would get a horrible stomach ache when I consumed raw honey. Same thing would happen when I ate broccoli or avocados. I only recently figured out that I have a problem with FODMAPs. I have had food allergies and GI issues for years. That was just the tip of the iceberg though.Turns out I have hypothyroidism which is most likely the root cause of my stomach problems. I also have SIBO and am currently undergoing an herbal protocol to get rid of it. Conventional doctors DO NOT HAVE A CLUE about how to treat functional GI diseases. See a naturopathic doctor if you want to get well.

    • Amina Jillo says:

      Our blood types also greatly influence our digestive systems.

  5. I am both lactose and fructose intolerance. Not sure what started first, but now I can drink only lactaid milk and eat yogurts with chess adding lactose tablets. If I drink regular milk I will get diarrhea for few days or weeks. Fructose stuff is much more complicated because there is no any good enzyme to help to break it down. I can eat only bananas and avocados, they have very low levels of fructose. I wish to eat apples or pears, they smell so good, but whenever I eat even small bite, it makes me feel sick like I got cold symptoms, then diarrhea and allergic reaction on belly skin. Also if I eat bad quality chocolate I get bad itching acne on my face and neck. And I cannot eat fresh vegetables anymore. Probably my intestines are so sensitive so it just causing the same diarrhea problems. I wish one day they will find some good enzyme for breaking down fruts. I want to eat all frutes as I used when I was a child.

  6. I am so relieved to find that my problem is real and not imagined. To find a specialist who listens instead of just sending you off for another colonoscopy; and insisted on visiting a pelvic floor Physio and dietitian before he did anything else – I am forever thankful. Done the elimination now on stage 2. Boo hoo I love mangoes but they are now out of my diet.

  7. Ann Buttner says:

    I just received this diagnosis. In addition I have an issue with bacteria. I suffer from diverticulitis as well, and had colon resection 5 years ago. I was doing well until about 18 months ago! I am relieved that they have figured it out, as I cannot stand having anymore tests or cleanses! I am meeting with a dietician and my gastro doc tomorrow. Praying for some relief! Any good advice, suggestions, or direction would be most appreciated!

  8. I get really bad migraines and stomach migraines from chocolate and citrus fruits. I also get intestinal issues from all fruits except bananas and ale vegetables. It’s really difficult because it doesnt quite cole under anything 😕

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