Testing for Leaky Gut – Putting the Pieces Together

Dr. Doni, Naturopathic doctor, explains the causes of leaky gut and offers her views and advice on how best to test for it.

Part 2 of Dr. Doni’s Series on Leaky Gut

leaky gut, intestinal permeability, food sensitivities, food intolerances, gluten sensitivity, digestion, digestive system, intestines, inflammation, IBS, stress, zonulin, actomyosin, lactulose, mannitol, natural health

Many people suffer from leaky gut (intestinal permeability), but don’t know they have it. They are puzzled by symptoms that just won’t go away such as fatigue, IBS, anxiety, aches and pains, unexplained headaches, and allergies for many years—never suspecting that all these seemingly unrelated symptoms have the same cause. The problem is that many traditional doctors aren’t looking for leaky gut (some don’t even believe it exists) and those who are aware of it don’t always know how to find it.

In the first article of this series, we covered what leaky gut is and the common symptoms associated with it (and diarrhea is not one of them). This time I want to show you how to test for leaky gut in order to find out for sure whether you have it. But before we dive into testing, let’s first get clear about the potential causes and degrees of severity.

What Causes Leaky Gut

When they are healthy, the walls of the small intestine are designed to allow nutrients to seep through into the bloodstream so they can travel to where they are needed in the body. The tiny gaps between the cells of the intestinal walls, called ‘tight junctions’, are joined together with proteins, sort of like Velcro. However, these cells and the Velcro that hold them together are susceptible to damage from the following:

  • Gluten—the protein in wheat, spelt, barley and rye.
  • Inflammation caused by:
    • Infections, such as viruses, bacteria, parasites, and/or yeast.
    • Dysbiosis, which is an imbalance of good bacteria (too many or too few) often caused by the overuse of antibiotics.
    • Irritation from medications such as anti-inflammatories (NSAIDS).
    • Food allergens, such as casein, whey, soy protein, and egg whites.
  • Stress—emotional or physical stresses alike.
  • Alcohol and caffeine.
  • Decreased digestive enzymes and/or stomach acid.

What Happens When the Gut is Leaky

When the intestinal cells and connecting proteins are damaged by any of these triggers, the gaps between them grow bigger, allowing substances to travel across the intestinal lining that wouldn’t usually be able to get through such as bacteria, protein, indigestible fibers, and complex sugar molecules. It also means that sugars that should get digested by enzymes produced by the intestinal cells won’t be digested or absorbed well.

And it is not just the intestinal cells that are affected in leaky gut. The proteins in the tight junctions are also damaged causing them to release a protein called actomyosin into the bloodstream.

There is a common misconception that the causes and symptoms of leaky gut are the same for everyone and that you either have it or you don’t. I find that Leaky Gut is actually a spectrum from mild to severe that can affect everyone in unique ways. In other words, the pieces of your puzzle may be different from others when it comes to finding the root cause.

Keep in mind that there are trillions of cells that make up the lining of the wall of the small intestines. The degree to which they are damaged determines the extent of leaky gut symptoms and how they will affect you. For some people, leaky gut will be associated with higher than normal levels of certain proteins in the blood (such as actomyosin) and/or a hormone that opens up the spaces between intestinal cells called zonulin. For many people, food proteins that leak through trigger an immune response—we would call this a food sensitivity. For others, the main culprit will be undigested complex sugars seeping through from the small intestine and/or unabsorbed sugars being fermented in the digestive tract. Because of this, not all tests are good at diagnosing leaky gut at all degrees of severity.

Available Tests for Leaky Gut

Testing for leaky gut is relatively new and more tests are being developed as we speak. The tests that are currently available are:

  • Breath test
    This simple test measures your ability to digest table sugar. Healthy intestines have no trouble digesting it, but when your intestines are damaged due to leaky gut, this test is able to detect changes in the pH level of your breath.
  • Urine test
    This measures the absorption of complex carbohydrates (lactulose and mannitol) across the lining. Lactulose should not cross the lining, so when it is found in the urine it indicates that the lining is leaky. Mannitol should cross the lining, so if it is not found in the urine then it tells us the cells are not absorbing nutrients well.
  • Blood tests
    There are two blood tests on the market at the moment. One tests for actomyosin and other proteins that are released when the intestinal cells and tight junctions are damaged, tells us if intestinal cells are being actively destroyed. This test is offered by a lab called Cyrex. The other tests for zonulin, a hormone that opens up the tight junctions, increasing gut permeability and allowing all the nasties to get out of the intestine and into the blood stream.

How Accurate Are These Tests?

Because testing for leaky gut is still being developed, I believe that we will see an increase in the accuracy of testing over the next decade. In the meantime, these tests can be useful for identifying more severe cases of leaky gut. However, since leaky gut can exist in differing severities, has different causes for different people, and because addressing even mild leaky gut is beneficial for your health, these tests have limited usefulness at this time.

Getting the Right Tests Done

Short of doing all the tests on everyone—which is costly, time-consuming, and invasive—I find that there is one simple test that both provides information about leaky gut and helps us figure out how to address it. It’s called an IgG and IgA food sensitivity test. That’s because when the body is producing antibodies to food, we know the intestinal lining must be leaky. I also find that the number and type of reactive foods can help us identify the presence and severity of the leakiness.

As we saw in the previous article in this series, when leaky gut exists, even to lesser degrees, it allows undigested food and proteins to leak through the intestinal lining and trigger the immune system. So by testing for immune reactions to specific foods, and the proteins in food (gluten, casein and whey for example), we can not only get a sense of whether leaky gut is present but can also identify the foods that are perpetuating the inflammation and intestinal damage at the same time. This is why I choose a food sensitivity test for most of my patients.

Closing Thoughts

The journey toward healing your leaky gut is a long one that requires commitment and dedication. Determining whether you have leaky gut is only the first step on this journey, but it is an important one that allows you to be sure that you’re treating the right thing. If you’d like to find out whether you have leaky gut and have my help with healing it you may want to check out my Leaky Gut Solutions Package.

You can find the next article in this series here: Healing Leaky Gut in 5 Simple Steps.

In a future article, I’ll also discuss the relationship between leaky gut and irritable bowel syndrome (IBS) and we’ll also look at how to address leaky gut. To make sure that you don’t miss future articles in this series, you can subscribe to this blog or to my newsletter below.

–Dr. Doni

19th June 2015

Photo credit: “It Looks Insoluble” by David Goehring is licensed under CC BY 2.0. Changed from original: Added text overlays.


  1. I use L-Glutamine as it does help in the repair process of the intestinal lining, but still more work to do to lessen the bouts, and identify triggers etc, I tried to subscribe but I don’t know if it did.

  2. My kiddo will be three in June. I feel like he has this, but is that common in a little one? He’s had allergy testing: 4+ allergic to chicken, eggs, tomatoes, bananas, grass and mold. He has horrible functional constipation that is greatly helped by cutting gluten (because it gives form when he poops). His eczema really clears up when gluten is cut on top of his allergens. I just assumed since he tested neg for Celiac and all his tests: colonoscopy, endoscopy and biopsies were normal that we were in the clear. But due to the gluten being so effective in helping his BM problems and skin, I’m thinking he’s a pretty good match for leaky gut: allergies, eczema, constipation and pain with BMs, bloated stomach, fatigue and he has tubes that were preceded by many antibiotics. Plus he lives on cheerios and yogurt.

    So… with all that said I’ve started researching all this. I’m a Spanish adjunct and my husband a pastor… no medical background for either! From my take, leaky gut fits our little one but my husband hasn’t bought into to all of this (probably some due to all the bills we’ve racked up trying to get a solution – all of which have turned out neg). So, sorry for the long spill, but my question is, is this all effective for a 3 yr old kid?

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