Fiona Lawson | 11 Jan 2021 | Gut Health

Stool Testing – The Ultimate In-Depth Guide (2021)

Are you thinking about taking a stool test? From finding a good test kit to working out whether you need to check for parasites, this article is a comprehensive guide to stool testing in the UK.

Read on to discover how to choose a stool test, how to take it and—most importantly of all—how to understand your results.


About stool tests
Understanding a stool test report
Stool testing purpose, procedure, duration and results
H. Pylori stool test
Stool testing for parasites
Stool testing on the NHS
Stool test kits
The future of stool testing

About stool tests

A stool test involves analysing a sample of your stool (poo) for bacteria, microbes and special markers of gut health. Anyone can take a stool test, though they’re used for different reasons:

1) To look for something specific
The NHS uses stool tests to look for a particular type of bacteria or substance. For example, if someone has recurrent diarrhoea, a doctor might order a stool test to look for the bacterial strain Clostridium difficile [1]. The NHS also uses stool tests to look for blood in people’s poo, which can be an early sign of bowel cancer [2].

These tests are useful for people who need a specific answer to a specific question (i.e. am I infected with C. difficile?). They are helpful but—because they only look for one thing—they don’t give you an overview of your gut as a whole.

2) To look at all bacteria
Other tests (typically called ‘microbiome’ tests) look at all the bacteria in your gut. Culturing bacteria used to be a slow and expensive process, but new technology means scientists can identify bacteria quickly by looking at their genes [3].

This type of stool test is interesting if you want a snapshot of your gut bacteria, but it still doesn’t give you the full picture. This is because your gut also contains other microbes and important substances.

3) To look at gut function as a whole
Comprehensive stool tests not only look at all the bacteria, but they also look at other microbes such as yeasts, archaea and even parasites. You can harbour all or some of these, and they have a big impact on your gut health.

But the best tests on the market don’t stop there. They also look at functional markers, such as:

· Calprotectin, which indicates gut inflammation [4]
· Secretory IgA, which indicates immune activity in the gut [5]

This type of stool test is best for people who want insight into their overall gut health. Together, the bacteria and functional markers can help you to understand why you’re experiencing certain symptoms.

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Understanding a stool test report

Depending on the provider, it will take between ten and 56 days to receive your stool test results.

Let’s presume you’ve taken a comprehensive stool test. It will show you:

a) Bacteria and other microbes
Bacteria and other microbes (such as yeasts) are measured on a scale. Your results will show whether each bacteria or microbe is ‘in range’ or ‘out of range’.

In-range microbes typically have a commensal or friendly relationship with you, while out-of-range microbes can contribute to dysbiosis and other gut problems [7]. One out-of-range bacterium doesn’t mean your gut is unhealthy, though—it’s more important to look at the overall ‘shape’ of your microbiome.

According to current knowledge, an in-shape microbiome has two key characteristics [8]:

· Richness, meaning it has high numbers of bacteria

· Diversity, meaning it has many different types of bacteria

So, for a healthy gut, you want high numbers of lots of different types of bacteria—or one that’s rich and diverse. A good stool test report should show you both the number and types of bacteria you harbour.

b) Parasites
Parasites are measured differently to bacteria, so you’ll either get a positive or a negative result.

A negative result means you have no detectable parasites. A positive result for one or more parasites means their DNA has been identified in your stool sample.

As you can read about in the ‘Stool testing for parasite’ section below, parasites aren’t considered a friendly part of the gut microbiome. Your test report (or your doctor) should explain how you can get rid of them.

c) Other biomarkers
Other biomarkers have their own ranges and units of measurement. Like the microbes, your test results will show whether these markers are in range of out of range.

Even if markers are out of range, they do not constitute a diagnosis. A high-quality test report will explain what might cause out-of-range biomarkers, and what you can do to address them. This may include diet, lifestyle and supplement advice, or it may suggest that you visit your doctor for follow-up investigations.

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Stool testing purpose, procedure, duration and results

A stool test gives a snapshot of what’s going on in your gut—kind of like taking a photograph.

The NHS uses stool tests in hospitals, but most stool tests are designed to be taken at home. You’ll need to follow a few steps before taking the test to maximise its accuracy. These include:

· Following your normal diet for at least a week before taking the test.
· Stopping probiotics three days before the test, as these can skew results.
· Making sure you take the test on a Monday, Tuesday or Wednesday, and planning to go to the Post Office on the same day (or within 12 hours).

Once you’ve prepared properly, there’s no best time of day to take a stool test—just do it when you have the natural urge to do a poo!

The instructions will vary by test provider, but the process is usually straightforward. Here’s how it works at Healthpath:

1) Make sure you’ve prepared properly by eating your normal diet and stopping any probiotics three days before taking the test.

2) Check you have the correct test kit (the instructions tell you what’s included) and label the two test tubes with your name and the date.

3) If you need to urinate, do this first. Then attach the stool collector to the toilet basin. Pass stools as normal.

4) Put on the gloves. Unscrew the lid from one of the test tubes, and use the spoon to take samples from several different areas of the stool until the test tube is two-thirds full. Repeat this process with the second test tube.

5) Screw the tops back on the test tubes and put them in the transport tubes. Remove the gloves and use the antibacterial wipes to clean your hands.

6) Along with your patient form, put the transport tubes inside the shipping bag provided and return it to the lab within 12 hours of collection. To ensure they get to the lab in time, you can only post samples on Monday–Wednesday (do not post the on Thursday, Friday or Saturday).

All of these steps are necessary to ensure you get as clear a snapshot of your gut as possible. But the process is easy, and it should take no longer than ten minutes to collect your sample. The results will show which microbes you harbour and whether anything is ‘out of range’.

Although the instructions will be similar, the prices of stool tests vary by provider. The more comprehensive a stool test, the more expensive it will be. Depending on what you want to test for, you can expect to pay in the region of £80–£400.

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Stool testing infographic

H. Pylori stool test

H. pylori is often included in more comprehensive stool tests.

Helicobacter pylori (or H. Pylori for short) is a type of bacteria. It’s special because it has adapted to live in the harsh, acidic environment of the stomach—where most other bacteria can’t survive. H. pylori’s spiral shape means it burrows into your stomach lining, where it’s covered by your stomach’s mucous layer. This prevents your immune cells from reaching it [9].

H. pylori is estimated to be present in up to 60% of people worldwide [10]. Most of the time it’s symptomless, but around 10% of infected people will go on to develop gastric ulcers [11]. These can cause severe abdominal pain, especially when your stomach is empty. Some people with H. pylori can also develop gastritis.

If you experience gnawing abdominal pain when you’re hungry (or a few hours after eating), it could be worth choosing a stool test that includes H. pylori. Other symptoms of H. Pylori infection include:

· Excessive burping
· Bloating
· Nausea
· Heartburn
· Lack of appetite

It’s important to realise that these symptoms are non-specific, and they’re seen in other gut conditions too. Other clues that it could be worth testing for H. pylori include:

· If you live with someone with a known H. pylori infection. This makes you more likely to have it.

· If you’ve tested positive for methane-dominant SIBO. Research suggests there an association between H. pylori and small intestine bacterial overgrowth [12].

For an H. pylori stool test, a lab technician will use a special type of technology to identify antigens associated with H. pylori. If a significant number of these antigens are found, your stool test report will show a ‘positive’ result for H. Pylori. If it’s a good test report, it will also tell you how to address it.

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Stool testing for parasites

Unlike many bacteria, parasites are considered to be unfriendly microbes. They can be identified in a stool test.

We tend to pick up parasites from eating food or drinking water that’s contaminated with faeces, or through travelling to developing countries. Examples of parasites found in stool tests include:

· Blastocystis hominis
· Dientamoeba fragilis
· Giardia lamblia
· Entamoeba histolytica
· Cryptosporidium species
· Cyclospora cayetanensis

Worms (helminths) are types of parasites too, though these are much rarer.

If you’re infected with a parasite, you can have no symptoms at all. But there’s also a chance a parasite can make you feel very unwell. You could experience:

· Diarrhoea
· Abdominal pain
· Flatulence
· Fatigue
· Constipation
· Flatulence
· Skin conditions

Again, these symptoms are non-specific, so they don’t necessarily mean you have a parasite. But it can be worth testing for parasites if you’ve made several dietary and lifestyle tweaks and these symptoms still aren’t improving. It’s also useful to test for parasites if these symptoms started after a trip to a developing country.

Stool testing is an easy, non-invasive way to test for parasites. A lab technician will use qPCR technology to look for parasites and their eggs in your stool sample. If any are detected, your stool test report will show a ‘positive’ result for the relevant parasite.

Parasites aren’t included in most standard microbiome tests, but Healthpath’s Advanced Gut Health Test and Ultimate Gut Health Test includes all the parasites listed above. Once you’ve returned your stool sample, you’ll get your results within ten working days.

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Stool testing on the NHS

At the time of writing (December 2019), it’s not possible to take a comprehensive stool test through the NHS.

As mentioned in the ‘About stool tests’ section, the NHS does use stool tests, but only for specific reasons. A key reason is looking for blood in stools to screen for bowel cancer.

In the UK, all men and women between the ages of 60 and 74 are sent a stool test kit every two years [13]. The NHS used to send out a faecal occult blood test (a FOB test). Two problems with this test were that it wasn’t specific to human blood (so it could detect animal blood eaten through the diet) and that it required six samples to be accurate.

This has been replaced with the faecal immunochemical test (a FIT test). This updated test detects just human blood, and only requires one sample. Since the FIT test’s introduction in June 2019, the number of people taking a stool test to screen for bowel cancer has increased [14].

These types of tests are important—and for some people, critical—but their only purpose is to show if you have blood in your stools. They don’t give you an overview of your gut health as a whole.

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What’s included in a stool test kit

The majority of stools tests available on the market can be posted to you. They’re usually slender enough to fit through your letterbox, so you shouldn’t have to wait around for a delivery.

Each test kit is slightly different, but they all contain the basic apparatus needed to collect a sample of your stool. Healthpath’s test kit includes:

  • 1 x test instructions sheet
  • 1 x patient request form
  • 1 x stool collector
  • 2 x transport tubes
  • 2 x test tubes with spoon-lids
  • 1 x pre-paid shipping bag
  • 1 x pair of gloves
  • 1 x antibacterial wipes

When looking for the best and most comprehensive stool test, you not only want to make sure that the test kit is easy to use, but you also want to find out:

a) How the lab handles your sample
Here at Healthpath, we make sure that people return their samples within 12 hours of collection, and we also take steps to ensure the samples get to the lab in a timely manner. This helps the samples to remain viable—so your results are a true representation of your gut health.

There is no standard way of analysing stool samples. Our partner lab combats this by taking part in a voluntary scheme in which it periodically analyses a dummy sample along with several other labs. This helps our lab to make sure its testing methods are as accurate and reproducible as possible.

b) How the company explains the results to you
Before purchasing any stool analysis test, it’s wise to ask for a sample stool test report. You want to make sure the test report highlights and explains any out-of-range bacteria or biomarkers.

A good report should never suggest it’s giving you a ‘diagnosis’ (the scientific community doesn’t yet know enough to make definitive statements), but it should include possible reasons for the out-of-range figures. It should also give you specific, targeted advice to help bring your gut back into balance. After all, data is useless unless you know what to do with it.

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The future of stool testing

Stool testing has come a long way in recent years—and there’s much more to discover.

The hope is that, in future, we’ll understand the gut microbiome to the degree that we can work out a person’s ideal diet based on their bacteria and biomarkers. That’s the ultimate goal of the ‘personalised nutrition’ industry.

Stool testing may also prove useful in predicting disease (both inside and outside the digestive system), and in working out exactly how a person metabolises certain drugs. This will help inform ‘personalised medicine’.

But there’s still a long way to go. Before we achieve personalised nutrition and personalised medicine, we need to work out:

What a healthy microbiome looks like. We’re aware of certain patterns (such as more proteobacteria indicating dysbiosis), but we still don’t know what an ideal microbiome looks like. Discovering this is a complex task, as it likely varies by age, location and even gender [15].

Which mechanisms contribute to disease risk. We know that some bacteria are associated with an increased risk of certain diseases, but we don’t know why. The secret may lie in analysing the substances created by bacteria (their ‘metabolites’) rather than the bacteria themselves [16].

How best to analyse stool samples. As mentioned in the ‘Stool test kits’ section, there is no standard method of analysing stool samples. This means that labs can cause different methods—leading to very different results. As soon as there’s standardisation (like there is with blood testing), we’ll be able to compare studies to reach more conclusions.

The good news is that every time you take a stool test, you’re helping to progress this research. We may even get to the point where the NHS sends out a comprehensive stool test every year to see how each individual is faring! Until then, your best option to order a high-quality, private stool test.

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Stool testing is used for several reasons. The NHS uses stool tests to investigate specific bacteria or biomarkers, while private stools tests provide insight into your gut health as a whole. The most comprehensive stool tests not only look at bacteria, but also investigate yeasts, H. pylori, parasites and other functional biomarkers.

You can take most stool tests at home. You’ll need to make sure you’re properly prepared by eating your normal diet and stopping probiotics three days before taking the test. Once you’ve collected your sample, you need to post it back to the lab as quickly as you can. This helps the results to be as accurate as possible.

Stool testing has seen great advancements in the last few years, but there’s still a long way to go. With every test, you’re helping the scientific community to work out how to monitor and adapt our gut microbiomes for optimum health.
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Fiona Lawson BA (Hons) DipCNM mBANT is a Registered Nutritional Therapist and health writer. She is a member of the Complementary and Natural Healthcare Council (CNHC) and the Institute for Functional Medicine (IFM). As Content Director of Healthpath, Fiona is on a mission to help people take charge of their own health. Read more about Fiona on her practitioner page.

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3. BMJ
11 Mayo Clinic
13 NHS
14 Cancer Research UK
16 BMJ

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