Gut Tests

Unsure if you need a Gut Test?

The gut is usually where we start looking for clues in any chronic condition, especially in any kind of food sensitivity, digestive issues like boating, wind, poor immunity, autoimmunity, but also for things like brain fog. Have a read of these factsheets and see if anything resonates with you: IBS, SIgA, SIBO, Leaky Gut, Allergy & Intolerance, Low Stomach Acid, Acid Reflux/Gerd, Candida.

Testing Summary

The best overall gut test is the DD GI360 (RG). It just gives so much useful, practical information about your gut. I especially like the markers included to help find causes of food sensitivity. For other gut tests like Candida, SIBO, Leaky Gut, H Pylori etc, see the recommendations below.

The GI360

After a detailed review (2020) of the gut tests available – no easy task, I can tell you! – I rate the DD GI360 (RG) as the best gut test around. The DD CSAP3 (RG) is a bit cheaper because it doesn’t include the extensive PCR testing, but is still very useful. You can read my blog post here if that helps:

Gut Tests Review – GI-MAP, GI-360 or GI -Effects?

And here is a comparison of the main tests that might be useful.

Gut Tests GI360, GI Effects, GI-MAP Comparison Chart

Essentially, the GI360 covers PCR and MALDI-TOF types of testing for bacteria, yeasts (including candida), parasites and some key gut viruses, but also uses microscopy and culture to confirm things.

It gives you useful clinical information on inflammation levels, malabsorption, short chain fatty acids (important for food sensitivity, infections etc), leaky gut, blood presence and SIgA (the gut immunity and food ‘safety’ marker) and also gives you an idea of what natural and antibiotic remedies any ‘baddies’ found are most sensitive to – in your particular case.

You have the option of doing 1, 2 or 3 day collections – I always prefer at least 2, preferably 3, because parasites hide and you’ve more chance of finding them.

If you wish, you can do versions with Zonulin (a leaky gut marker) and/or H pylori. If you wish to check the markers (ie. the inflammation, SCFAs, absorption etc) but not the microbiome, you can do that using Stool Chemistries (RG).

GI360 Overview & Results Resources

Here is a full introduction to the GI360 and how to interpret your results when they come back. Plus a new Gut Test Guide on how to read and treat your results. I hope it helps!


Candida and yeasts are covered in the comprehensive tests above, but I often advise people confirm – or start with, if all they want to know is if candida is present – the Candida SAPS Test (PHC). This is the only test I know of that looks for a specific protein marker released by pathogenic yeasts. If the yeast or candida found is SAPS positive, it needs treating. Everyone has some yeasts and even candida in their system; what you actually want to know is: is yours a problem and does it need treating?

Happily, this test also includes a mouth swab. This is important because often we find candida in the mouth rather than the gut. This shows it is trying to colonise through the mouth and you are vulnerable. You can then take steps to combat that. Check the Candida Factsheet out here.

SIgA (Secretory IgA)

This is a measure of mucosal immunity (ie. in the gut, sinuses, vaginal areas etc). Put simply, if your SIgA level is too low, you will find it very difficult to fight off ‘baddies’ like yeasts and bacteria. You then need to work to raise your levels first. If your SIgA is too high, it suggests an acute problem somewhere – usually inflammation, infection or a sensitivity to something (eg. a food intolerance). You can read much more about SIgA in my SIgA factsheet here.

SIgA is measured in the stool tests but you can do it separately too. Do BTS SIgA Stool (PHC).

SIBO (Small Intestine Bacterial Overgrowth)

The Breathtrackers SIBO breath test (RG) is a good choice here. You can do either the SIBO Glucose or SIBO Lactulose (both RG). SIBO guru Alison Siebecker recommends lactulose mostly but there is a school of thought that it is best to do both.

For info, the ingredients of the lactulose substrate in tests is usually 10 g lactulose (and less than 1.6 g galactose, less than 1.2 g lactose, and 1.2 g of other sugars). Also contains FD&C Yellow No. 6, purified water, USP and wild cherry flavoring. A minimal quantity of sodium hydroxide, NF is used to adjust pH when necessary. (Not dairy free). And the glucose: DEXTROSE, HYDROUS, POWDER, USP. Synonyms: Corn sugar; Dextrosol; Glucose, monohydrate (not grain free). However, please check with the labs before use as this may not be up to date!

Here is my video about SIBO testing – I did it on the Aero Diagnostics one originally but much of it holds true for any SIBO test:

There is also a new type of SIBO test from Cyrex now – Cyrex 22. This is very different to the breath test in that it is looking for antibodies to bacterial cytotoxins released in SIBO rather than the gases we produce. It also looks for evidence to see if the cytotoxins have caused a leaky gut. You can see more info on this sheet here.

Leaky Gut

In terms of leaky gut, a lot of the time you can assume it is present because of the case and just treat. If you have food sensitivity or autoimmunity, it’s practically a given. Testing leaky gut is surprisingly complex. There are several different markers and just because one says it is negative, it might well be that others could be positive. Of course, life would be simple if there was a test that looked at all the markers, but there isn’t yet.

The stool tests can be done including zonulin, a marker of attack on the tight junctions that keep the gut – and other – walls nice and strong. High zonulin shows a likely breached barrier. Or, you can take it one step further and use the Advanced Intestinal Barrier Assessment (RG), which also includes DAO and Histamine as well as the LPSs.

Stomach Problems

Most of the issues so far have concentrated on the lower gut, but what about the stomach? The first thing is to try the lemon/cider vinegar/bicarb or betaine tests – see here. You also want to see if you have any Helicobacter pylori, the very common cause of gastric issues and more besides. You can add H pylori onto the stool tests if they are not included, or you can do it separately as the H Pylori Antigen stool test (RG).

Testing Summary

The best overall gut test is the DD GI360 (RG). It just gives so much useful, practical information about your gut. I especially like the markers included to help find causes of food sensitivity. For other gut tests like SIBO, Leaky Gut, H Pylori etc, see the recommendations above.

Testing Tips…

Q: Why do you like the Doctors’ Data GI360 so much?

There are many gut tests. The reason I went for this one is that it is really comprehensive and uses PCR/DNA testing as well as MALDI-TOF analysis so you’re likely to find more ‘baddies’ if they’re there, plus a really useful raft of stool chemistry markers that allow me to see patterns causing eg. food sensitivity, or reasons for poor detoxification, why you can’t fight off infections well etc. It looks for actual fibres of veg and protein in the stool and includes a carbohydrate malabsorption check as well as fat. It also has lysozyme, a good inflammation marker the others don’t have (they all have inflammation markers but this is an extra in the Doctor’s Data version). It also includes occult blood (an important bowel cancer test) and a consistency check, which the others don’t. Bonus: it’s cheaper both to buy and to return to the lab.

Q: Why do you do a 3 day version? Can I do 1 or 2 days?

The reason I recommend three is that parasites hide and it is best to have a 3 day sample to give yourself the best chance of finding them. One tip: if you wish to make sure parasites are found, some practitioners suggest you ‘purge’ your bowel eg. using Vitamin C, magnesium or something from your health shop/pharmacist (not salt or castor oil) on the 3rd day so you get a ‘clear-out’ if you like. Then use that for your third day sample. Yum!

Q: Sadly, I don’t go to the loo that often. What if it takes me several days to get the three samples?

I asked the lab this for someone who was taking 9-10 days to get the three samples, which is about the limit really I would say. They advised: The samples need to be with us within 4 days of the LAST day – the chemistry tube (frozen) and the parasites (preservative) keep them viable. The culture tube on the last day is the most time sensitive.

Q: Any advice on stopping supplements etc?

For gut tests, my standard advice is to do the following unless you are monitoring yourself on them – please be led by your health professional and the specific instructions in your test kit/on the lab sites; these are my general tips:

Please make sure you stop taking any probiotics (bacteria eg. acidophilus) at least 5 days before doing the test.

For candida, stop any form of anti-fungal (eg caprylic acid, oregano, garlic etc) at least a week before. You should stop taking all anti-fungal supplements at least a week before you take your sample (e.g. caprylic acid, garlic capsules, grapefruit seed extract, oregano oil). Two days before you take your sample avoid fungi-food eg. camembert, brie, stilton, kefir, kombucha and stop taking any probiotics for 5 days before the sample is taken. Natural probiotic yoghurt is fine.

For parasites, stop taking any anti-parasitics at least a week before.

For the pancreatic function test, this will be affected by any pancreas meds and pancreatic enzyme products, including glandulars.

The SIgA and leaky gut tests will be affected by any supplements designed to assist them eg beta glucans, glutamine, saccharomyces boulardii, collagen etc, so stop these a few days before unless you are monitoring yourself on them.

Immune-suppressant medication may affect the inflammatory markers, specifically Calprotectin and Eosinophil-Protein X, though the labs cannot predict exactly how these medications may impact the test results. They say: “We never recommend patients discontinue medically prescribed medications in order to do testing. With regards to medicines in general, we cannot know for certain how long a specific dosage will impact test results. Patients on regular medications can continue during testing to see how they are impacting. However if the medication is temporary they may choose to wait until the medication course has been completed.” Wise words.