Hydrogen breath testing used to be used routinely to diagnose food intolerances and is still currently used to diagnose SIBO. It is not painful and runs very few risks to an individual’s health.
In this article I will explain why I wouldn’t recommend a hydrogen breath test for food intolerance diagnosis anymore. I will also go through the role within SIBO diagnosis.
What Is A Hydrogen Breath Test Used For?
A hydrogen breath test is used to test for lactose intolerance, fructose intolerance and small bowel bacterial overgrowth (SIBO).
The test works by detecting carbohydrate malabsorption e.g. sugars such as lactose and fructose or it can be the result of an overgrowth of bad bacteria e.g. SIBO.
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How Does The Hydrogen Breath Test Work?
Lactose Intolerance Testing
Normally, lactose is broken down in your small intestine to form glucose and galactase. This process is done by an enzyme called lactase (3).
If you do not break down the lactose properly in your small bowel, it reaches the large bowel and is broken down by bacteria producing hydrogen (3).
Levels of hydrogen found in your breath which are significantly higher than your usual levels are said to indicate an intolerance (1).
The tester will also make note of any digestive symptoms such as diarrhoea and stomach cramps. If these symptoms do not occur, your results may be the result of something else (3).
Fructose Intolerance Testing
You will be given a water based drink containing 25 – 50g of fructose. Again, hydrogen measurements will be taken from your breath every 30 minutes for 4-5 hours (1).
Fructose is usually absorbed in the small bowel and does not need any enzymes to help it (4).
In fructose malabsorption, the fructose does not get absorbed in the small bowel and instead travels to the large bowel taking lots of water with it. In the large bowel it meets lots of gut bacteria and again hydrogen (amongst other gases) is produced (4).
Unlike testing for lactose, fructose testing is not as accurate or as useful. This is due to the lack of good quality studies providing an ‘optimal’ fructose dose for testing (1).
Not only this, but most foods that contain fructose, also contain glucose. Glucose helps to absorb fructose and so if you test positive, it may be that you can actually tolerate a good bit of fructose, despite being ‘intolerant.’
Short Intestinal Bacterial Overgrowth Testing (SIBO)
To test for SIBO, a water based drink containing either glucose or lactulose is provided. Breath tests are then taken every 15 minutes for up to 3 hours (1. Both hydrogen and methane measurements are taken during this test (5).
Lactulose can not be broken down by the human gut and is usually used as a laxative. When it is taken during this test and a rise in hydrogen or methane is shown, this indicates that there is bacteria in the small bowel breaking it down.
Glucose can be broken down by either bacteria or absorbed in the small bowel. When bacteria breaks down glucose, it gives off hydrogen. Therefore, any increase in hydrogen shows that there is unusual amounts of bacteria (SIBO) in the small bowel. Glucose is absorbed at the start of the small bowel and so is a good test substance to use as it doesn’t involve mechanisms further down the gut (1).
How To Get A Hydrogen Breath Test
Due to new research suggesting that hydrogen breath testing is not accurate for food intolerance diagnosis it is no longer used in most practises.
For SIBO testing, this will need to be carried out by a gastroenterologist or can be organised in a private clinic.
Please note that if you opt to go privately that you should be prepared to pay not only for the test but subsequent gastroenterology appointment and antibiotics if this is not covered by private health insurance.
Accurate Food Intolerance Diagnosis
There is currently no test out there which will accurately diagnose a food intolerance. Instead, you will need to carry out an elimination diet with a registered dietitian.
Symptoms which go away when a food is eliminated and then come back when the food is reintroduced will form a diagnosis.
Hydrogen breath testing is only partly accurate for SIBO diagnosis and even this is controversial. Some gastroenterologist do not use this test and will go off symptom history alone.
Hydrogen breath testing is not an accurate way to diagnose food intolerances and can lead to false results. Instead, you will need to undergo an elimination style diet such as the low FODMAP diet with a dietitian to pin-point your sensitivities.
To book in for help with a food intolerance, contact me today.
Kirsten Jackson is a UK registered Consultant Gastroenterology Dietitian and founder of The Food Treatment Clinic. She has undergone many qualifications to get where she is today, including a UK BSc Honours Degree in Dietetics and Post-Graduate Certificate in Advanced Dietetics. In addition to this, she has FODMAP Training from Kings College London University. Kirsten set up The Food Treatment Clinic in 2015 after first experiencing digestive problems herself. She felt that the NHS was unable to provide the support individuals needed and went on to specialise in this area before opening a bespoke IBS service. Kirsten also participates in charity work as an Expert Advisor for the IBS Network. In addition, she can be seen in publications such as Cosmopolitan and The Telegraph discussing IBS as an Official Media Spokesperson to the IBS Network.