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What Causes Leaky Gut?

Leaky gut, or intestinal permeability, describes the loss of intestinal barrier function where things leak through which shouldn’t.

Our intestinal tract is complex – it’s responsible for digestion and absorption of the nutrients we consume, but it’s also exposed to food antigens, commensal bacteria, pathogens and toxins [1]. We have a specialized barrier which can selectively block certain things but absorb others.

Leaky Gut is Real

Leaky gut used to be a concept – something without proof or science backing it. Now, after 35 years more and more research has emerged proving its role in health and disease. Leaky gut has been proven to contribute to various autoimmune disease such as Inflammatory bowel disease (crohn’s and colitis), Autoimmune hepatitis, Type 1 diabetes, Multiple sclerosis and Systemic lupus erythematous (SLE). Other conditions such as alzheimer’s Disease, depression and cancer are also associated with it.

More information can be found here, where I discuss what leak gut is and the proof of its role in medicine.

Causes of Leaky Gut

Diet Induced Leakiness

There are many dietary influences known to cause leaky gut or intestinal permeability. The exact mechanisms aren’t always known, but we know there is a cause and effect relationship.

  • Low Fiber: triggers mucus-degrading bacteria [2]
  • Low Vitamin D: vitamin D is recognized to protect against intestinal permeability. It induces the expression of two proteins which keep things intact (the proteins are called f TJ proteins ZO-1 claudin-1). Vitamin D can come from sunlight, but also certain foods.
  • Western-style diet
    • Diets excessively high in fats, carbs and proteins are associated with excess amounts of circulating bacterial wall lipopolysaccharide. This is associated with systemic inflammation as well[3].
  • High Fructose: diets high in fructose are also associated with loss of tight junction proteins occludin nd ZO-1 [4]. This is mainly from high fructose corn syrup and not as much fructose from fruit.
  • Hyperglycemia: (high blood sugar) drives intestinal barrier dysfunction and risk of infection [5] by affecting the integrity of tight junctions and intestinal and splenic immune system. High blood sugar also increases infection [5], which you’ll see below is another cause of leaky gut.
  • Increased use of industrial food processing and food additives:increased intestinal permeability seen with additives including sugar, metal oxide nanoparticles, surfactants and sodium chloride [6]
  • Alcohol consumption: chronic consumption is known to lead to intestinal barrier dysfunction, alterations in quality and quantity of gut microbiota, lipopolysaccharide translocation, and alcoholic liver disease [1]. Most of the changes pertaining to intestinal permeability arise from changes to gut bacteria.



As we all age, certain gut changes are inevitable, including the gut bacteria. These specific changes which occur with aging have been shown to result is increased intestinal permeability, systemic inflammation and immune dysfunction [7]. Luckily supplementation and proper medical assessment allows for proper intervention.

Stress-induced gut leakiness

The gut and brain have very strong connections. During times of stress, we see reduced gut healing. If the gut doesn’t heal properly, intestinal permeability or leaky gut may ensue.

Major stressors, such as burns are well documented to have profound changes to gut permeability [1].


Various alterations to the gut microbiome are associated with leaky gut/intestinal permeability. We’ve seen associations between leaky gut and protozoan infections [8], H. pylori and a wide range of other intestinal infections [1]. Gram negative bacterium directly increase epithelial permeability by redistributing connective proteins called TJ protein ZO-1 [1].

Oxidative Stress / Hypoxia / pH alterations

A constant supply of oxygen is crucial for every cell in our body, including our gut. Disturbed oxygen supply can affect normal gut balance. Oxidative stress is damage induced by oxygen free radicals, and hypoxia is diminished oxygen supply. Basically, reduced oxygen supply or oxidative stress can both lead to leaky gut. The degree of hypoxia found in the intestinal mucosa is exacerbated significantly in inflammatory bowel disease, leading to a more extensive and severe hypoxia and subsequently leaky gut [9] [10]. pH alterations can come about when there is oxidative stress or reduced oxygen. When the pH changes, this too can independently lead to leaky gut [10].

Proinflammatory Cytokines

Sometimes a result of infections or dysbiosis, inflammation is it’s own driving force behind intestinal permeability [11] [10].


Understanding the multitude of causative factors behind leaky gut is valuable. Since many of these are lifestyle factors (such as diet), simple changes can be made to have profound effects. Also, by understanding how leaky gut arises, we can supplement appropriately. A number of nutrients may be helpful for intestinal permeability or leaky gut, be sure to talk to you naturopath today to learn more.


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