Breath Testing has been commonly used to diagnose intolerances to certain fermentable sugars (e.g. FODMAPs) that are associated with symptoms of Irritable Bowel Syndrome (IBS).
Did you know that we all have 1-2kg of bacteria residing in our intestines? We provide these bacteria with a food to eat and place to live, and in return they keep us and our guts healthy. When certain sugars (i.e. FODMAPs) are poorly digested in the small intestine they continue along the digestive tract to the large intestine. In the large intestine they are fermented by the resident bacteria and gases such as hydrogen and methane are produced as a side effect. In theory these gases can be measured in a breath test and the results used to potentially identify malabsorption of certain FODMAP groups.
In this article we’re going to cover what breath tests are, how accurate breath tests are, and what is the most reliable way to identify your IBS triggers.
Breath testing is a non-invasive and low-cost way to measure sugar malabsorption. During this test you will be provided with a drink containing a dose of concentrated sugars such as lactose or fructose. Once you have had the drink, you will then be require to breathe out into a bag every 20 minutes over a 2-3 hour period to measure the level of Hydrogen in your breath.
A laboratory will then analyse the amount of hydrogen captured in the bag and report back to you if the amount was high or low. While a high hydrogen breath amount can identify that you malabsorb fructose or lactose, it doesn’t necessarily mean you are intolerant to them. Read on to find out why.
The short answer is YES. Although these tests are commonly used, the research shows they can be unreliable.
In 2016, Monash did a review of different studies to find out whether or not breath tests are reliable (you can read the study here). The research team found out that:
The short answer is No. Not only is there a huge variability in testing results and testing methods but the quantity of lactose or fructose given during breath tests can also be unrealistic when compared to your normal eating habits.
People doing breath tests are provided with up to 35g of fructose or 50g lactose to drink prior to the breath test. This is equivalent in fructose to 4 pears, 1 mango, and 3 teaspoons of honey in one sitting OR the amount of lactose in a full 1 litre of milk. Now, most people would not usually consume this much fructose or lactose in one meal. And, this much lactose or fructose can make everyone feel gassy or bloated, even if you do not have IBS.
Although malabsorption of FODMAPs can cause symptoms, it won’t shorten your lifespan and it doesn’t result in any damage to the body. In fact some FODMAPs (e.g. the Oligosaccharides) are supposed to be malabsorbed and are FODMAPs for all humans. In everyone they will ferment in the large intestine and create gas as a side effect. It’s just that some people have a more sensitive gut than others and this will be more aware of what is going on. This fermentation is actually a good thing because these foods and the gasses produced as a side effect have anti-inflammatory properties and contribute to keeping your gut microbiome healthy.
Managing malabsorption is purely about minimising any symptoms that result from eating a food and subsequently improving quality of life. Meaning that if a food doesn’t cause symptoms, it does not need to be limited. And, if it does cause symptoms, it only needs to be limited enough to minimise those symptoms and keep you comfortable. This approach will give maximum food variety and minimum symptoms, which ultimately is the ideal result.
Breath testing alone does not determine:
If you have had a breath test and you were told that you malabsorb fructose or lactose then it’s important that you confirm the results with a food challenge. The same goes if you’ve been told you don’t malabsorb these sugars but are still having symptoms.
A structured food elimination and challenge process can identify which foods trigger your symptoms (both FODMAP and non-FODMAP sensitivities) and what your threshold levels are for specific foods. People who follow this process guided by a specialised dietitian have been shown to get better symptom improvement and restrict less foods.
At Everyday Nutrition we are FODMAP trained qualified dietitians and nutritionists who specialise in managing all types of IBS and food sensitivities. We do virtual consults and you can receive personalized dietary advice on how to feel better by booking a consultation to get help from one of our friendly dietitians.
This article was written for Everyday Nutrition by Meher Vatvani and reviewed by Joanna Baker APD.
Meher is a Nutrition Science student who is passionate about gut health and nutrition. She loves cooking and baking.