Small Intestinal Bacterial Overgrowth (SIBO) test

SIBO Test

€185.00

Small Intestinal Bacterial Overgrowth (SIBO) is a common cause of IBS symptoms. If identified, SIBO can in many cases be eradicated or managed.

Who can benefit from this test?

Your nutritionist may recommend this test if you have:

Digestive issues including reflux, irritated stomach or bowel, distension or bloating, feelings of extreme fullness after eating, cramps, diarrhoea or constipation, fatty or floating stools
Reactions to foods which may be difficult to pin-point
Immune-related issues such as skin rashes, unexplained joint or muscle pain, autoimmune or immune-related fertility issues
Unexplained fatigue, brain fog, energy imbalances
Weight loss-resistance, problems with insulin resistance

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Breath test (in clinic or at home)

Under normal conditions, most of our bacteria are far down the digestive tract, in the large intestine. The small intestine should have much lower numbers of bacteria. However, in SIBO, larger numbers of bacteria are found in the small intestine, causing a range of symptoms.

The SIBO test works by measuring the gas production by bacteria in your small and large intestine. For accurate results, you will need to follow a strict diet for 1-2 days pre test and you will be provided with this dietary plan in advance of your test.

The test measures two types of gas – hydrogen and methane. This can help to identify different types of bacteria in the gut so that your Nutritionist can tailor your protocol effectively. The presence of methane-producing bacteria (Intestinal Methanogen Overgrowth, IMO) are more often associated with constipation where hydrogen-producing bacteria are usually associated with loose stools or diarrhoea.

Lactulose (a sweet liquid) is consumed. Once bacteria come into contact with this liquid, they will ferment the sugar and produce gas. This goes into your bloodstream and out in your breath. As the solution travels down through your gut, gas is produced when there is bacteria present. If you produce gas early on in the test procedure, this means that the bacteria is high up in the digestive tract – in the small intestine. If you do not produce any gas until very late in the test, this can be simply due to normal bacteria much lower down in the digestive tract. Therefore by measuring the output of gas over time, we can determine where the bacteria is located and how much there is.

This test measures:

Hydrogen gas and methane gas production in the breath over three hours

- Download SIBO Sample Report

We published this case study in a medical journal to demonstrate the efficacy of testing SIBO and treating it with a herbal antimicrobial formula.

‘IBS symptoms described by the patient as severe for at least 10 years. Symptoms included bloating, cramps, flatulence and constipation along with fatigue. Intolerance to garlic was severe, causing vomiting and thus the patient completely avoided its consumption.

A strict low FODMAP diet was recommended under the supervision of a nutritional therapist using the Monash University FODMAP University App for the most up-to-date food list. A herbal supplement termed Candex SIBO (Nutri Advanced) was used to support the eradication of small intestinal bacteria.

The follow-up breath test revealed a marked improvement. The result was classified as negative for SIBO. Hydrogen gas output indicated normal colonic bacteria and methane was completely absent from the sample throughout.

The patient reported feeling considerably better and her quality of life global score increased from 42 to 71. Specifically, in the categories of activity and discomfort where she was previously categorised as extreme, there was a marked improvement, where her digestive symptoms no longer had an impact on her quality of life.’

Reference: C Wright, M Dooley, H Leeson (2021) Eradication of Small Intestinal Bacterial Overgrowth (SIBO) in Irritable Bowel Syndrome using herbal therapy; a case study. International Journal of Functional Nutrition 2:5

Open access paper here

SIBO Test FAQ

How can this test help me with my digestion?

The lactulose breath test helps us identify small intestinal bacterial overgrowth (SIBO) — a condition where bacteria that belong in the large intestine migrate into the small intestine and interfere with digestion, nutrient absorption, and gut motility. If you experience bloating, gas, abdominal discomfort, reflux, constipation, diarrhoea, or food intolerances, this test gives us objective data about whether bacterial fermentation in the small intestine may be driving your symptoms. Rather than guessing or endlessly eliminating foods, we can use your results to guide a targeted, personalised treatment plan.

I’ve already seen a gastroenterologist, how is this different?

Gastroenterologists are essential for ruling out serious issues, and many people we work with have already done this step. However, SIBO testing is not routinely performed in standard gastroenterology care. The lactulose breath test helps us uncover patterns that may not show up on conventional testing, allowing for root-cause driven support, not just symptom suppression.

I have already done a test for lactose intolerance, how is this different?

A lactose intolerance test looks specifically at your ability to digest lactose, a single sugar found in dairy. While helpful, it does not explain why you may be reacting to multiple foods or experiencing ongoing digestive symptoms. The lactulose breath test assesses bacterial fermentation in the small intestine, which can cause symptoms that mimic food intolerances — including reactions to dairy, fructose, and FODMAPs. In many cases, treating SIBO improves tolerance to foods that were previously problematic. If food reactions feel widespread or unpredictable, SIBO testing can help clarify whether bacteria — not the food itself — are the issue.

I am on a low FODMAP diet, can I still do the test?

Yes — and in fact, many people on a low FODMAP diet are ideal candidates for SIBO testing. While symptom reduction is common on this diet, it does not address the underlying cause and is not intended as a long-term solution. Before testing, we’ll guide you through specific preparation instructions to ensure accurate results. The goal is to move beyond long-term restriction and towards restoring digestive function and food tolerance where possible. If you’ve been stuck on low FODMAP with lingering symptoms or fear of food reintroduction, SIBO testing can help guide your next steps.

Should I also do a comprehensive stool test like a GI Map or will this test tell me everything?

The lactulose breath test and comprehensive stool testing (such as GI Map) assess different parts of the digestive system. SIBO testing focuses on bacterial activity in the small intestine, while stool testing evaluates the large intestine, inflammation, digestion, and microbial balance. In some cases, SIBO testing alone is sufficient. In others, combining tests provides a more complete picture — particularly for complex, long-standing, or recurrent symptoms. We don’t believe in unnecessary testing; we recommend investigations clinically, based on your history and symptoms. If you aren’t sure which tests are right for you book a consultation and we’ll create a tailored testing plan — no guesswork, no over-testing.