How Do You Know If You Have A Leaky Gut? Quick Answers

The term ‘leaky gut’ is controversial. 

While a growing number of world-leading doctors, scientists and researchers believe that leaky gut—also known as intestinal permeability—plays a large role in many of our modern, chronic illnesses, others insist that it’s a made up condition used to sell supplements.

If you want to know the truth about leaky gut, and how to tell if you have it, read on.

Is leaky gut real?

Intestinal permeability is definitely real. There’s no doubt about that.

But experts don’t agree on whether or not it’s a cause of disease. That’s because everybody’s gut is leaky to some extent: your gut is designed to let some substances through into the rest of your body, and keep the rest in.

The problem happens when your gut starts to let out the wrong things. When certain substances escape from within your gut, your body’s immune system reacts. This is the basis of leaky gut syndrome.

Leaky gut is kind of trendy right now: it’s all over the internet, which could explain why clinicians from more traditional backgrounds are suspicious of it.

The weight of evidence behind the connection between leaky gut and chronic disease is now too heavy to ignore [Source: PubMed] [Source: PubMed]. But we still don’t know for sure if it causes these diseases: we just know it’s a part of the picture.

In other words, it’s possible that the diseases cause the leaky gut, rather than the other way round.

Could it be leaky gut?

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What is leaky gut?

In a nutshell, leaky gut happens when the walls of your intestines let out things they shouldn’t into the rest of your body.

Remember that your gut is just a hollow tube that connects your mouth to your anus. Everything inside of your gut is technically outside of your body. The job of your gut is to let only certain particles and substances out, and keep the rest in.

When it’s working well, it does a good job of that. But sometimes, the task gets harder.

If the gut lining becomes weak, toxins, bacteria and other particles can ‘leak’ through this barrier into the bloodstream. Because those things aren’t meant to be in your bloodstream, your immune system launches an attack against them [Source: PubMed]. That response from your immune system can trigger a wide range of symptoms and over time, could play a part in developing chronic disease [Source: PubMed].

Symptoms of leaky gut

The symptoms of leaky gut can show up almost anywhere in your body [Source: PubMed]. Some signs of leaky gut could include:

Leaky gut may also be an underlying factor in a number of conditions, including:

What causes leaky gut?

We can’t be completely sure what causes leaky gut, but our modern lives appear to be the culprit. That means things like:

Check out our Symptoms and Conditions pages to find out more about what causes leaky gut.

Leaky gut seems to exist alongside SIBO and dysbiosis (an imbalance of the communities of microbes in your gut) [Source: PubMed], but we can’t say for sure which comes first, or if one causes the other.

However, research is mounting to support the theory that SIBO or dysbiosis comes first [Source: PubMed]. This is good news, because it means that if we tackle SIBO and/or dysbiosis, we automatically address leaky gut too.

People who live in traditional communities who still eat only whole foods and drink little or no alcohol don’t suffer from the same chronic diseases or health issues as us. While there hasn’t been any research into levels of leaky gut in traditional communities, we know they have diverse gut microbiomes with no dysbiosis [Source: PubMed].


How do you test for a leaky gut?

There are many ways to test for a leaky gut. One method is the ‘PEG’ (which stands for ‘polyethylene glycol’, a solution that you drink). Another one measures levels of a substance called zonulin in your stool.

You can find out more about leaky gut and how you can test for it on our blog Leaky gut syndrome: the complete guide.


Leaky gut syndrome tests

The PEG test

For this test, you drink a sugary solution and collect all the urine you pass for six hours afterwards. Through measuring the types of sugar that end up in your urine (each of which have different-sized molecules), you can know whether or not your gut is more permeable than it should be. 

Though this test will give you an accurate picture of the permeability of your gut, there are factors that can affect the result, like how fast your gut moves, medications like ibuprofen, the surface area of your intestines, and the speed that your blood flows through your gut.


Your gut uses an incredibly complex system to make sure that only the right stuff goes out from it into the rest of your body. We don’t yet know exactly how this process works, but in 2013 a doctor called Alessio Fasano discovered that a substance called zonulin governs the opening and the shutting of the microscopic ‘holes’ in your gut wall [Source: PubMed].

On this basis, the higher your zonulin levels, the leakier your gut. You can find out your zonulin levels by taking one of our Gut Health Tests. However, a high zonulin reading doesn’t necessarily mean you have a leaky gut. There are other reasons why your zonulin could be high, so your result from this test should only form one part of your health puzzle. 

That’s why we don’t recommend a stand-alone zonulin test, but include it in our Gut Health Tests. As part of a comprehensive investigation into your gut health, a zonulin reading is a useful tool.

Find the cause of your leaky gut. Test your gut health

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How do you fix leaky gut?

Leaky gut happens for a reason. Healthy people don’t develop leaky gut out of nowhere: something happens ‘upstream’.

If you have the symptoms of leaky gut, which could be anything from gut symptoms like diarrhoea, constipation or bloating, to autoimmune diseases—for example rheumatoid arthritis, endometriosis or eczema—you need to address your gut health.

That means finding the root cause, which is likely to be one or more of the reasons above.

If you suspect your root cause could be SIBO, you can take a SIBO Breath Test. You can check if you have the symptoms of SIBO in our blog SIBO symptoms: what they mean and what to do next

Taking a Gut Health Test is a good idea, because all our Gut Health Tests give you a window into the goings-on of your large intestine. The results will reveal whether the communities of microbes living in your gut are living together in relative harmony, or dysbiosis has taken hold.

While a zonulin reading (which is included) is a useful piece of the puzzle, it’s just one element of the picture of your gut.

If you have SIBO and/or dysbiosis of the large intestine, you’ll need to follow a protocol by one of our Registered Nutritional Therapists or Functional Medicine Practitioners, which is included in the test price. By addressing these, you’ll automatically tackle leaky gut too.

The best way to support leaky gut is with a fibre-rich [Source: PubMed], whole food, plant-heavy diet. Eat as many different plants as possible to support your gut microbes, which in return will support your gut lining.

The following nutrients are leaky gut superstars:

  • Vitamin D and vitamin A [Source: PubMed]: excellent sources are oily fish and liver.
  • The amino acids glutamine [Source: PubMed] and tryptophan [Source: PubMed]: you can find them both in eggs.
  • Polyphenols [Source: PubMed] are plant chemicals which include legumes, onions, garlic, berries such as blueberries or raspberries, raw cacao, coffee, or tea.
  • Medium chain fatty acids such as capric and lauric acid [Source: PubMed], found in coconut milk and oil. (Update 8/4/2021: coconut oil is 87% saturated fat, which can contribute to leaky gut [Source: PubMed]. Taking a caprylic acid supplement could be a better way to get your medium chain fatty acids).
  • Short chain fatty acids [Source: PubMed] from the fermentation by our gut bacteria of fibre-rich foods, such as fruits, vegetables and legumes.
  • Fatty acids EPA and DHA [Source: PubMed] in oily fish like salmon or sardines.

Like we said before: leaky gut doesn’t happen out of nowhere. Your gut becomes leaky  because something isn’t right. 

The best way to fix leaky gut is by addressing your general gut health.

So, if you have any imbalances like SIBO, parasites or dysbiosis in your large intestine, address them first. Then get busy improving your gut health!

If you want some help getting great gut health, check out our Gut Health Program.

Key takeaways

  • Healthy guts let the right substances out and keep everything else in
  • Mounting evidence is showing that when your gut lets the wrong things out, it can lead to disease
  • More and more experts now agree that leaky gut is a major player in the dramatic increase of chronic disease
  • There are tests for leaky gut, but we recommend them only as part of a bigger investigation into your gut health
  • To fix leaky gut, you need to address any infections, imbalances or dysbiosis and support your gut health with the right diet and lifestyle


Alexandra Falconer MA (Dist) DipCNM mBANT is a Registered Nutritional Therapist specialising in IBS and related conditions. A graduate of Brighton’s College of Naturopathic Medicine, she is committed to fighting the root causes of chronic illness and bringing functional medicine to everyone who needs it.

Before her natural health career, Alex was a journalist and copywriter. She continues to write for magazines and media agencies, and now combines her two great passions—writing and health—by creating content that empowers people to claim their right to a healthy body and mind.


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