10 Fructose Malabsorption Symptoms

  • Posted on: 1 June 2016
  • By: Brett
fructose malabsorption symptoms stomach

Naturally occuring Fructose can be found in a range of foods that you wouldn't expect like apples, pears, honey, and even some vegetables.

This is on top of the sources that we already know about like soda and other heavily processed foods that you buy from the store (like peanute sauce!). 

While for most people, digesting fructose is not a problem, one in three people are UNABLE to absorb this fructose properly in the small intestine, which leads to a range of fructose malabsorption symptoms.

When fructose is unable to be digested, it travels to the large intestine, where bacteria consumes it and releases carbon dioxide, hydrogen, and methane gas into the body.

This can result in many uncomfortable gastrointestinal symptoms and can lead to other neurological symptoms as well...

...below I’ve broken down the top 10 fructose malabsorption symptoms into these 2 categories and tried to explain why they occur in the first place!

Gastrointestinal symptoms of fructose malabsorption

  1. Bloating
  2. Flatulence
  3. Reflux
  4. Stomach pain
  5. Nausea/Vomiting
  6. Diarrhea/Constipation

Gastrointestinal symptoms are the most common complaints of fructose malabsorption sufferers.

The gas produced by the bacteria in the large intestine after it consumes the excess fructose will result in flatulence, bloating, and reflux.

You may experience stomach pain as a result of muscle spasms, from chronic, mild spasms to acute and severe.

If you consume too much fructose in a single sitting and your body cannot absorb it, it may try to expel the fructose instead, leading to nausea and vomiting.

The large intestine will pull in too much water to aid the body in absorbing nutrients when it detects an imbalance, and this excess water will lead to diarrhea.

Further irritation of the large intestine and colon can result in the body alternating between diarrhea and constipation.


Neurological symptoms of fructose malabsorption

  1. Fatigue
  2. Mental depression
  3. Headaches/Brain Fog
  4. Mood changes

When the body cannot absorb fructose, it also loses the ability to absorb many important nutrients.

...this is for two reasons...

  • First of all, diarrhea (the most frequent symptom of fructose malabsorption) will cause the body to flush nutrients too quickly from the body;
  • Second of all is that when the normal bacteria in the large intestine gorge on the abnormal presence of fructose, the intestinal flora is left unbalanced.

Fructose malabsorption will thus lead to many nutrient deficiencies, specifically of folic acid, iron, tryptophan, and zinc, and vitamins C, D, and E.

All of these nutrients are vital for different operating systems in the body, and especially are related to healthy brain function.

For example, lack of folic acid can cause brain fog, mood changes, headaches, and fructose malabsorption depression, while iron deficiency will prevent oxygen from reaching the brain in adequate amounts and thus lead to fatigue.

Meanwhile, tryptophan is an essential amino acid that our bodies synthesize into serotonin, the absence of which is a key precursor to depression.

What are the symptoms of Fructose Intolerance?

  • The symptoms of fructose malabsorption include bloating, flatulence, reflux, stomach pain, nausea, vomiting, diarrhea, constipation, fatigue, mental depression, headaches, brain fog, mood changes.


Similarities to other food allergies

If you experience gastrointestinal distress, fructose malabsorption may be the culprit.

Note, however, that these symptoms are very similar for sufferers of lactose intolerance, gluten intolerance, and IBS (Irritable Bowel Syndrome).

In some cases, these conditions may overlap.

ALWAYS check with a doctor to get the proper diagnosis for your symptoms.


What to do if you experience these symptoms

Keep a food diary and start to eliminate foods that would cause fructose malabsorption.

Notice if there are any changes after you cut them out of your diet.

Try reintroducing the foods slowly and see how your body reacts. (Note: when making changes to your diet, it is best to do so with the supervision of a dietician.)

As with any case of experiencing symptoms such as the 10 listed above, schedule an appointment to see your doctor.

Your doctor can officially diagnose fructose malabsorption using a hydrogen breath test, a noninvasive test that monitors the amount of gas produced in your breath after you consume fructose.

The doctor may then prescribe a low-fructose diet that helps your body get back in balance.

So which symptoms do you get when you eat a bit of Fructose?
How long after you eat food with Fructose in it will symptoms materialise?
How long does it last before you're back to normal?

Please leave your comments below...


Hi Bret, I have been readying about fructose malabsorption, I have been having terrible pain in my stomach, feels like a flu bug, into my small intestines. Terrible gas, bloating, extension etc. than it happens about 1/2 hour after I eat fruit or raw vegetables, Onions, garlic and raw peppers etc. Than the pain sets in about 1/2 and it last for 2 to 3 hours. I usually have to take gas pills and tylenol to help with the pain, than I get extremely tired all day. I just wanted to know if you think this is fructose malabsorption before I go to the doctor for the gruling test? I am afraid to drink this fructose drink for the pain I will have.

Hi Dianna, without having the test, its hard to tell if you have fructose malabsorption or not. It is well worth the short term discomfort of completing the hydrogen breathe tests, than suffering from bloating every day. I strongly suggest that you speak to a doctor and go get tested. I hope this helps. Brett

I definitely notice I get the neurological symptoms mentioned in this article when I eat a ton of fruit. I made the mistake of making myself a big fruit smoothie with bananas, mangos, berries, and a few dates. I got a short burst of energy and it was all downhill from there. I had a massive headache that lasted 4 hours. It pretty much stopped shortly after I ate a steak/veggie/potato dinner. Oddly enough I notice this doesn't happen to the same degree when I eat other forms of sugar. I can eat lots of sweet potatos without getting that massive sugar crash. Very weird

i have been suffering with this for over 25 years, and for the last 11 yrs can only eat pasta as a dinner meal, my can eat list is down to approx 6 items. I CANNOT Thank You enough for this info and can't believe I haven't seen this before. Thank You!

Hi Bret. I've had malabsorption problems following the Magrath Protocol some 10 years ago. Fructose malabsorption diagnosed after a hydrogen breath test in 2008. A few years ago at my annual with my oncologist, my blood was loaded with iron. Liver biopsy revealed Hereditary Hemochromatosis. Any advice on how to combine these two? Thanks for the nice site.

Is there any point in getting diagnosed? I have known for ten years if I eat fructose I'm in trouble. I've been using FODMAP guidelines for years but have gotten worse in the last three years and deal with constant fatigue. As far as I know there is no treatment for this, and I had to explain to my new doctor what a FODMAP was.

Hi Brett My 7 year old has fructose malabsorption - he became unconscious after drinking the syrup. We are doing our best on the FODMAP guidelines however have become aware that he is extremely constipated. He will not eat any sweet food at all - this includes all fruit with the exception of an occasional tomato, olives or avocado. What foods can we try to assist him before we have to have medical intervention for him.

It might be worth having a few sessions with a dietician to get his diet on track.

My 15 year old was diagnosed with Fruct Mal, at the Mayo Clinic in 2015. His symptoms don't come on right away after he eats or drinks something, sometimes it can take a week. Onions are his biggest culprit, if he has even a sliver it can put him down a week. For instance he had Chicken Tortilla soup (which they were told not make with salsa)last Thursday, he of course ate half the bowl before he saw the onion slivers, and we are down today. I wish there was an enzyme you can give them daily to help counteract the severity of the attacks, or at least push them through quicker. Poor kid I hate when this happens to him.

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