Fructose Intolerance Test: What to Expect from a Hydrogen Breathe Test for Fructose Malabsorption

Posted in fructose malabsorption on March 27, 2018

If you are experiencing symptoms of gastrointestinal distress, your doctor may have scheduled you to take a hydrogen breath test. 

The hydrogen breath test can be used to detect Fructose Malabsorption (sometimes called Fructose Intolerance).

The hydrogen breath test can be used to diagnose food allergies, such as lactose intolerance and fructose malabsorption, as well as IBS (Irritable Bowel Syndrome).


Test Yourself at Home?

Did you know that you can order a home fructose malabsorption testing kit to see if you have fructose malabsorption?

Aerodiagnostics have available a breathe test kit that you can use at home.

Click here to order your fructose breathe test kit online.

But what will you need to do to prepare for the test, and what will happen on test day?


We’ll tell you all you need to know to feel comfortable going into the test and how to interpret the results when you come out.


How does the hydrogen breath test (Fructose Intolerance Test) work?


  • When the body doesn’t absorb certain sugars, like fructose or lactose, those substances pass into the large intestine where bacteria consume them and produce gases as byproducts.

The most common types of gaseous byproducts produced are hydrogen and methane, which are not usually otherwise found in the body.

When there is an elevated level of hydrogen and/or methane in the body, this points to the body’s intolerance to a type of sugar.

The hydrogen breath test is used to measure how much hydrogen is in a patient’s breath in short intervals after a probable irritant is ingested.

For example, if you and your doctor suspect fructose malabsorption as the probable cause of your gastrointestinal symptoms, you will ingest small amounts of fructose in a clinical setting and the doctor will monitor whether the amount of hydrogen in your breath rises...

...if it does, this is a clear indicator that your body is unable to absorb the fructose. If it doesn’t then there may be another culprit, and you can retake the test the following day by ingesting a small amount of lactose, for example.



How to prepare for Frucose Intolerance test day

For an accurate reading of your hydrogen breath test, it’s very important that you follow a strict diet beforehand.

  • You may not take antibiotics anytime within four weeks of the test. This is because antibiotics throw off the body’s digestive bacteria and could result in a temporary weakening of the body’s ability to absorb fructose and lactose;
  • You may not take laxatives within one week of the test, or undergo a colonoscopy or barium enema in this timeframe. Again, this is because you want the test to reflect how your digestive system normally functions and not after it has been otherwise manipulated;
  • Avoid high fiber foods the day before the test, including beans, pasta, fruits, and vegetables. Don’t consume any sugar the day before the test;
  • You should not eat or drink anything within twelve hours of the test. This includes both water and gum. Brush your teeth two hours before the test, but try not to do it any closer than that to your appointment time; and
  • You may take your usual medications up to twelve hours before the test. Then, if you must take anything the morning of the test, take it with just a small sip of water and bring the medication with you to show the doctor.

Your doctor should provide you with a comprehensive set of instructions of the diet you are required to take pre testing.

What to expect during the hydrogen breath test

When you arrive at your appointment, the doctor will ask you if you have had anything to eat within the past twelve hours.

If the answer is yes, you will have to reschedule. If no, the doctor will collect your baseline breath sample reading by having you blow into a bag.

Then you will take a small solution of fructose or lactose (depending on which substance you and your doctor suspect to be the irritant).

You will then take breath samples every fifteen minutes for the next two to four hours.

You may not eat, chew gum, smoke cigarettes, or exercise during this time.

Once you have completed the hydrogen breath test, you will be able to leave and immediately go back to eating a regular diet.

The doctor will receive a report about how much hydrogen was detected in your breath.

If the hydrogen levels in your breath increased over your testing period, then the doctor will talk with you about diets and options to manage your food allergy.


What does a fructose Intolerance test show?

  • A hydrogen breathe test for fructose shows the g/L of Hydrogen detected in your breath.


What does fructose test positive mean?

  • A positive test to fructose from a hydrogen breathe means that your stomach is unable to digest fructose properly and your doctor may advise you to adopt a low FODMAP diet.

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