Breath Testing


Breath testing can be helpful to identify conditions such as fructose malabsorption and lactose intolerance, however they are not useful for identifying the many other dietary conditions that people can have. Dietary trials with an experienced dietitian at Shepherd Works can assist with identifying and managing a range of dietary intolerances while achieving a nutritionally balanced diet.


How Do The Tests Work?


The procedure for each test (fructose, lactose, sorbitol and lactulose) is simple. You need to perform each breath test on a different day. When you attend each breath test appointment you will be given a hydrogen breathalyser type device to breathe into. This first sample is recorded, then you will be given a sugar solution to drink, after which another breath sample will be taken from you every 15-20 minutes over the next 2~3 hours. Many people complete the tests for Lactulose, Fructose, Sorbitol and Lactose within 2 hours, although some take around 3 hours. Your referring practitioner will describe which of the test sugars (Fructose, Sorbitol or Lactose – or any combination of these) you are to do. However, a practice test, (a Lactulose test) must be performed prior to any of these test sugars, to make sure you produce enough hydrogen gas. If you are a low- or non-hydrogen producer with Lactulose, you will be changed from the breathalyser device to inflatable bags during the course of your test as these bags allow us to also measure methane gas. This will ensure that we capture whichever type of gas (hydrogen or methane) you produce.

Generally, if you do not absorb the test sugar in your small intestine, then that sugar will continue through to the large bowel. In the large bowel, the sugars are then broken down/fermented by the bacteria that naturally live in the large bowel, and gas is produced. Although some gas is lost out the back passage (as wind/flatus), the majority is absorbed across the walls of the large intestine into the blood stream. In the blood stream, the gas is then carried up to the lungs. The lungs then take up the hydrogen and/or methane gas and it is breathed out. During the breath test conditions, if a rise in gas (hydrogen/methane) levels are detected on the breath after the sugar test, then it may indicate that that sugar is malabsorbed in the small bowel (as hydrogen and methane are not usual gases that are expelled by the lungs in such conditions).

Where Do I Go To Have These Tests?


The breath hydrogen and methane tests are performed at various centres.

To make an appointment with a dietitian click here

Where to next?

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