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Best Diet for Leaky Gut: A Dietitian’s Perspective

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Have you heard of Leaky Gut?

The world of nutrition and wellness is ever-evolving and there are certain terms that seem to pop up with increasing frequency. One such term that has gained A LOT of attention recently is “leaky gut.” If you’ve found your way to this post, you’re likely curious about what leaky gut is (just like many of my clients!)

As a registered dietitian, my mission is to help you understand the science behind leaky gut, explore its potential causes and consequences, and dispel some common myths. But ultimately, the science can be confusing. My main priority is to simplify the info that’s out there and provide you with actionable, real world advice to support a healthy gut barrier. 

So, let’s embark on a journey to demystify leaky gut!

A silver sink faucet leaking water

Table of Contents

  1. What is Leaky Gut?
  2. The Role of The Gut Barrier
  3. Conditions Linked to Leaky Gut
  4. Things that Can Impact the Gut Barrier
  5. Diet & Leaky Gut
  6. How You Can Strengthen Your Gut Barrier
  7. Supplements for Leaky Gut

What is Leaky Gut?

The term ‘leaky gut syndrome’ has gained lots of attention recently. However, leaky gut syndrome isn’t actually a recognized medical diagnosis. This terminology is a way of referencing that the lining of the digestive tract (also called the gut barrier) has become more permeable than it should be. This increased permeability can potentially lead to health complications – more on this later. 

Although ‘leaky gut’ is often referred to as a syndrome, it is not a formal medical condition in the health sciences. This is because there are no clinically validated medical or laboratory tests to confirm whether someone has it – nor are there established standards for what it means to have a non-leaky gut! We tend to see the term leaky gut being used most often in alternative medical settings, incorrectly referred to as a diagnosis. We prefer to think of leaky gut in a more scientific fashion – a change in intestinal permeability that is a result or driver of disease. 

The Role of the Gut Barrier

To truly understand leaky gut, it is first important to understand the role of the gut barrier, or gut lining. The lining of the intestines acts sort of like a bouncer at a nightclub – it decides who gets in and who doesn’t. The nightclub in this scenario is the bloodstream and we only want the best attendees to enter! 

The gut barrier is composed of multiple layers that are meant to selectively absorb essential nutrients while keeping harmful substances out. The layers of the gut lining, from the innermost layer to the outer layer, include:

  • The lumen – This is the space within the intestines and also contains water, bile, bacteria, and gastric secretions that help us to digest our food and prevent pathogens from populating the gut.1
  • The outer mucus layer – This is composed of a thick layer of mucus that is relatively loose and acts as a great place for beneficial bacteria to hang out. Many types of bacteria form colonies here. This is what we tend to think of when we hear the term gut microbiome!2
  • The inner mucus layer – This is a layer of tighter, more compact mucus that doesn’t house as many bacteria. The more inward we go in the gut lining, the less microbes we see. This is the final boundary before the last element of the gut lining.2
  • Epithelial lining – This is a single layer of epithelial cells, and other types of cells that help with production of enzymes, absorption of nutrients, and much more! The key to a healthy epithelial lining is cells that are tightly packed together. They are connected by tight junctions, which act as the final decision-makers about what comes in from the gut to the bloodstream.

When this barrier function is compromised, there appears to be a relationship with various health issues and symptoms throughout the body. But is leaky gut the root of all evils in the world of health? It’s not really that simple…

Conditions Commonly Linked to Leaky Gut

In certain circles, leaky gut has been connected to all sorts of health conditions including eczema, fibromyalgia, chronic fatigue syndrome, rheumatoid arthritis, Parkinson’s disease, and more.1 Many of these claims are based on little to no supporting evidence. 

However, since inflammatory processes have been connected to impairments in the gut barrier, it is plausible to assume that leaky gut could be a driver, or a symptom of already having a disease state that involves inflammation. It’s the classic chicken vs. egg scenario – what came first, leaky gut or a pre-existing inflammatory condition?

The real answer? It’s complicated. And we don’t really know much yet. Scientists refer to leaky gut as an ‘epiphenomenon’ – two things that happen at the same time but aren’t necessarily directly related to each other.1

Things That Can Negatively Impact the Gut Barrier

While we’re still learning, there are some factors that have been shown (in varying levels of research) to influence the permeability of the intestinal barrier including:

  1. Diet composition – particularly a Western diet consisting of high levels of fat and low levels of fiber.
  2. Altered gut microbiota
  3. High levels of inflammation in the gut
  4. Stress
  5. Alcohol
  6. Poor Sleep
  7. Lack of exercise
  8. Antibiotic use and other medications 

What is the Best Diet for Leaky Gut?

No surprise, there is no well researched ‘leaky gut diet’. As registered dietitians, it is our job to ensure that the diet interventions we recommend are coming from an evidence-based point of view. Since leaky gut is all a pretty big question mark, there’s really no gold standard when it comes to diet. 

The Western Diet & Leaky Gut

When it comes to leaky gut, one proposed theory for the presence of compromised gut barrier function is the western diet.  

The western diet is a dietary pattern that has become prevalent in many western countries like the USA, Canada, but also urban communities in general3. This dietary style is characterized by its high consumption of processed and convenience foods, which are often rich in saturated and/or trans fats, sugars, and refined carbohydrates. There is also a lower intake of vegetables and fruit and fiber in general than other dietary patterns. Although the roots of this diet are mainly in North America, the conveniences of this diet pattern have been adopted all around the world.

As a whole, those who consume diets low in fiber and high in saturated fats and animal protein appear to have reduced diversity of the gut microbiota.3 

Why is this? Research shows that dietary fiber is an important component for protecting the gut barrier and maintaining a healthy gut microbiota. When our gut bacteria consume fiber (prebiotics), they produce beneficial compounds called postbiotics.2 These postbiotics help to maintain the function of the gut barrier. Additionally, bacteria that don’t consume adequate fiber can start to look for fuel elsewhere, often finding it in the mucous layer of the gut. This can ultimately impact the integrity of the intestinal barrier. 

Additionally, high levels of animal fats in the diet may be linked to higher potential of leaky gut. Although we don’t yet have much human data on this, some in vitro and animal studies have shown that fat likely reduces the integrity of the gut barrier by impairing the epithelial lining.2 

So what are some evidence based things that can promote a functioning gut barrier?

It appears that a diet high in fiber and lower in animal proteins and saturated fats is the best approach to improve the integrity of the gut barrier. Women should aim for 25 grams of fiber per day, while men need about 38 grams. However, research shows that many North Americans struggle to hit these targets and generally only consume about 15 grams per day! 

Here are some tips for breaking away from the western diet:

  • Eat 2 cups of vegetables with both lunch and dinner
  • Aim for 30 different plant-based foods per week – the bacteria in our gut microbiome are picky eaters, so it’s best to provide many different types of plants!
  • Choose to go meatless 1-2 times per week – using legumes as your protein source instead. Or try a 50/50 split – I love replacing half my ground meat with canned lentils for things like meatballs or taco filling!
  • Limit consumption of red meat to no more than 2 times per week
  • Use cooking oils low in saturated fat such as olive oil (best for low temperatures), avocado oil, safflower oil, or canola oil. 

What About Supplements for Leaky Gut?

Since we don’t yet have defined diagnostic criteria for leaky gut, the research on supplements that alter gut permeability is also lacking. While supplements like collagen and L-glutamine are of interest, we simply don’t have the research to make any bold claims about these yet. At this point, if you hear someone on TikTok or Instagram raving about how “this supplement saved my leaky gut!” – it’s all hearsay. One person’s testimonial is not the same as well designed clinical studies. Not even close!

The Takeaway

While many people assume they have leaky gut syndrome, there isn’t significant evidence or diagnostic tools to tell us whether someone does have a ‘leaky gut’. 

If you’re reading this and you’ve already received a diagnosis of leaky gut from a health professional, hopefully this post allows you to consider that with a more discerning eye. Often a leaky gut diagnosis is used to sell you something – was that the case? If so – that is a red flag. Does that something happen to be a more balanced diet? If it’s beyond that, sorry to say but not only do we not have the evidence to diagnose leaky gut accurately, we also do not have the evidence to support particular supplements resolving it. 

What is evidence based? At this point – not a lot. Our best bet is to focus on a diet high in fiber to ensure your gut microbiota is well nourished. This encourages the production of postbiotics which can help to maintain a healthy gut barrier. 

All in all – leaky gut is a tricky topic. People on social media are making some pretty scary claims about the harmful effects of leaky gut, but the truth is, we just don’t know much yet. If you have further questions about leaky gut and how diet or supplementation may play a role in your digestive health, we highly recommend meeting with one of our dietitians.

A silver sink faucet leaking water

Categorized: Feature, Gut Health & IBS

3 responses to “Best Diet for Leaky Gut: A Dietitian’s Perspective”

  1. Hi,

    I suffer with collagenous colitis, colon lining. My diet is plant based, no gluten, no dairy, no nuts , no chocolate, no corn. No stress as much as possible. Plenty of fluids, probiotic, supplements B12, Zinc, D3, collagen etc…my diet is not boring, yummy. Without it I would be living the nightmare of nausea, bloating, pain and 24/7 on the porcelain throne.
    It takes determination, wouldn’t power and a desire to feel better.

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  1. Camilleri, M. (2019). The leaky gut: mechanisms, measurement, and clinical implications in humans. Gut, 68(8): 1516-1526, doi: 10.1136/gutjnl-2019-318427

  2. Usuda, H., Okamoto, T., & Wada, K. (2021). Leaky gut: effect of dietary fiber and fats on microbiome and intestinal barrier. International Journal of Molecular Sciences, 22 (7613), https://doi.org/10.3390/ijms22147613

  3. Makki, K., Deehan, E.C., Walter, J., Backhed, F. (2018). The impact of dietary fiber on gut microbiota in host health and disease. Cell Host & Microbe, 23(6): 705-715, doi: https://doi.org/10.1016/j.chom.2018.05.012