What is a hydrogen breath test and what does it diagnose?
Hydrogen breath testing is used fairly routinely to diagnose a range of gut health problems. It is not painful and runs very few risks to an individual’s health.
This article will talk you through the answers to these questions and iron out any questions you may have around hydrogen breath testing.
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.
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 will then indicate a lactose 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
Depending on where you live in the UK, you may or may not be able to get a hydrogen breath test on the NHS for food intolerances. So speak to your GP to see what your options are.
If the test is for SIBO then you will be advised on this via your gastroenterologist.
Privately, you can pay around £200 – £350.00 for the test.
Alternatively, you can see a specialist dietitian who can diagnose you with food intolerances via a specialist FODMAP diet or by a single food exclusion diet. However, please do not trial this on your own as it is complex and you may cause nutritional deficiencies.
Unfortuantely, there are no alternatives currently available for SIBO which are routinely used.
If you have any of the above symptoms then you need to see your GP. They will then start the procedure towards getting you the correct diagnosis via various tests which may or may not include a hydrogen breath test.
- If your initial tests come back negative, but you have not been tested for intolerances, you can book in with a dietitian who can advise you on a suitable diet to help diagnose.
- If your initial tests, including intolerance testing, comes back negative, you can see a dietitian to help find the cause and solution to your gut symptoms.
- If your tests come back suggesting food intolerances or coeliac disease, then you should see a dietitian to insure you are able to follow the correct diet required.
To book in for help with a food intolerance, contact me today.
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