Gut microbiota test
- Secondary relevance
- Requires a medical indication
Gut microbiota test on a stool sample using sequencing based on the 16S ribosomal marker. It describes the bacterial groups present and their relative abundance in the sample on the day it was collected. On its own it does not diagnose a digestive disease, nor does it make it possible to choose a personalised diet or probiotic.
Requires a medical prescription
Results in 3-4 weeks
Stool sample. Includes: Gut microbiota sequencing from a stool sample. See what it measures
The international consensus on microbiome testing, published in The Lancet Gastroenterology & Hepatology in 2024, explicitly advises against this test being requested on the patient's own initiative: there is not enough evidence to use it routinely and there is no accepted definition of an altered microbiota. It is offered here because it has its place within an assessment that a doctor has already set out, and that is why someone must have recommended it beforehand.
Secondary relevance. It is not the one I recommend to start with. It is here because it adds something in specific situations, but for most people it looks at more than is needed.
What it is for
It is used to obtain a description of the bacterial composition of a stool sample and compare it with a reference population. It can add information within a clinical or research assessment that has already been set out, when the responsible professional has defined in advance which question they want to answer.
Bear in mind that there is currently no universal definition of «normal microbiota» or «dysbiosis». The report does not on its own identify the cause of bloating, does not diagnose SIBO, coeliac disease or irritable bowel syndrome, and does not establish a treatment.
When it is recommended
- An assessment led by a doctor who has specifically requested a description of the microbiota
- Research or protocol-based monitoring of an intervention within a process that has already been set out
- Not recommended as a first test for bloating, wind, diarrhoea or constipation
- Not recommended for choosing a diet, a supplement or a probiotic
Clinical comment
The international consensus published in 2024 concludes that current evidence does not allow microbiota tests to be recommended routinely. It also notes that there is no accepted definition of dysbiosis and that direct requests without a clear clinical indication should be discouraged.
The composition of a sample changes with recent diet, antibiotics, probiotics and bowel habit. In addition, stool mainly represents the microbiota of the colon and does not describe every part of the digestive tract in the same way. A single sample should be understood as a snapshot of one specific moment.
We have kept this test available for situations in which a doctor has recommended it within a defined assessment. Its value lies in describing, not in turning a list of bacteria into a diagnosis or a personalised plan.
Dr. Antonio Mas
What is tested
• Gut microbiota sequencing from a stool sample (16S rRNA): Uses a bacterial ribosomal marker to identify groups of microorganisms and estimate their relative abundance. The result describes the sample, but it does not measure all the functional activity of the gut ecosystem.
- Gut microbiota sequencing from a stool sample (16S rRNA)
How to prepare
No fasting or appointment is required. The stool sample is collected at home with the kit provided by the partner centre.
Do not take antibiotics during the 4 preceding weeks, or probiotics or prebiotics during the 2 preceding weeks, unless a doctor has advised otherwise. Keep to your usual diet and hand in the sample following the kit's storage and timing instructions exactly.
You can add
Without another needle. It is offered when you order, so you do not have to decide now.
- General blood testA general blood test with full blood count, glucose, cholesterol and kidney and liver function: the basic parameters included in any general check-up.+€59.00
- General + nutritional blood testEverything in the general blood test (anaemia, kidneys, liver, cholesterol and glucose) plus iron stores, vitamin D, vitamin B12 and folic acid. It is the broadest add-on: it covers the general and the nutritional in one go.+€129.00
- Coeliac disease antibodiesMeasures the antibodies used to investigate coeliac disease; for a reliable result, it must be done while you are still eating gluten.+€39.00
Related blood tests
We have other profiles in Digestive with more or fewer tests:
- Fructose intolerance test€60.00
- Lactose intolerance test€60.00
- Sorbitol intolerance test€60.00
- SIBO breath test€64.00
- Helicobacter pylori breath test€69.00
- Coeliac disease blood test (antibodies)€69.00
- Vitamin B12 blood test€89.00
- Vitamin B12 blood test with antibodies€149.00
- Methylmalonic acid, for borderline B12 deficiency€149.00
- Coeliac disease genetic test (HLA DQ2/DQ8)€229.00
The most comprehensive is not always the most useful. Each profile page explains when it makes sense and when it does not.
Often checked together with
They are done from the same sample, so there is no extra visit.
- Coeliac disease blood test (antibodies)Before looking at the gut microbiota, it is worth checking for coeliac disease: it causes the same symptoms, it can be treated and it costs a fraction.€69.00
- SIBO breath testBacterial overgrowth explains many of these symptoms and, unlike the microbiota, its result does change the treatment.€64.00
What it is based on
This page is based on the international consensus on microbiome testing published in The Lancet Gastroenterology & Hepatology in 2024. The document concludes that there is still not enough evidence for routine use, that there is no accepted clinical definition of dysbiosis and that results should not be automatically translated into diets or treatments. The technique can describe differences between samples, but the ability to turn those differences into clinical decisions remains limited. That is precisely why this profile requires a medical indication and is marked as secondary relevance.
Porcari S, Mullish BH, Asnicar F, et al. · The Lancet Gastroenterology & Hepatology 10(2):154-167, en línea desde diciembre de 2024
International consensus statement on microbiome testing in clinical practice
Sixty-nine specialists from eighteen countries conclude that the evidence does not support routine use of microbiome testing and that there is no accepted definition of an altered microbiota, and they ask that anyone ordering it be aware of that limitation beforehand. This is the reason a prior medical indication is required here.
Protocol designed by Dr. Antonio Mas, specialist in Endocrinology and Nutrition, Spanish medical licence no. 080846289, and reviewed in September 2026.
This blood test is a standardised protocol and does not replace a medical consultation. If you have symptoms, a known condition or a complex clinical situation, speak to your doctor.