What May Cause Leaky Gut?

As we discussed in a previous post, symptoms of leaky gut, or increased intestinal permeability, are linked to various health conditions. However, what leads to leaky gut?

The mystery behind leaky gut persisted until 2000 when researchers discovered a human protein called zonulin. Zonulin plays a crucial role in controlling intestinal tight junction proteins, which, in turn, regulate intestinal permeability [1,2].

Two factors are known to trigger the secretion of zonulin: gluten and specific bacteria. We’ll delve into gluten below and address bacteria, or dysbiosis, in a separate post.

Gluten can potentially trigger “celiac disease,” an autoimmune condition that manifests as symptoms like diarrhea and fatigue. Some individuals also experience “non-celiac gluten sensitivity” (NCGS), which affects 0.5% to 13% of the population [3].

While gluten may contribute to leaky gut in susceptible individuals, adopting a gluten-free diet without confirming gluten intolerance is not advisable. In the context of leaky gut, the absence of dietary fiber might pose a greater risk than gluten for most individuals.

For those diagnosed with celiac disease or NCGS, a gluten-free diet can improve intestinal health. However, it is crucial to verify gluten sensitivity before making dietary changes. Gluten-free diets, which are restrictive diets, should be approached cautiously, as gluten-containing foods often provide valuable dietary fiber, which supports gut health.

High-Fat Diets and Gut Health

High-fat diets may contribute to leaky gut through various mechanisms, including the reduction of tight junction proteins, increased bile secretion, and the initiation of oxidative stress and inflammation. Although short-term human studies haven’t directly linked high-fat diets to leaky gut, they can raise blood levels of LPS, a gut bacteria metabolite that may trigger inflammation. Preclinical research strongly indicates a connection, and the potential for long-term effects on leaky gut cannot be dismissed [4,5].

Sugar and Refined Carbs

Research indicates that both sugar and refined carbs can contribute to leaky gut. While fructose is notably linked to this condition in animal studies, glucose may also play a role, potentially leading to inflammation before the onset of leaky gut [6,7]. Short-term human trials haven’t established a direct link between fructose or glucose consumption and an increased risk of leaky gut [8]. However, in individuals with diabetes, leaky gut appears to be more common and is correlated with heightened inflammatory markers [9].

Other Factors May Cause Leaky Gut

Leaky gut can also be triggered by stress, alcohol, medications, and dairy products.

Stress: High-intensity exercise can increase the risk of leaky gut by causing oxidative stress and inflammation [10,11].

Alcohol: Even a 5% alcohol concentration can induce leaky gut. A single dose of 20g of ethanol, equivalent to a small amount of beer or a glass of wine, can worsen intestinal permeability [12,13].

Medications: Non-steroidal anti-inflammatory drugs (NSAIDs) like aspirin and acetaminophen can lead to leaky gut within 24 hours of use [14]. Antibiotics can also disrupt gut function [15].

Dairy Products: Some proteins in dairy, like casein, may contribute to leaky gut, but there is limited human clinical evidence. Eliminating dairy should be based on confirmed allergies or intolerance. Fermented cheese and unsweetened yogurt may be better tolerated by some [16-20].

Summary

Zonulin plays a role in controlling tight junction proteins, which regulate intestinal permeability.

Although gluten is known to trigger the release of zonulin and cause leaky gut in predisposed individuals, it’s crucial to confirm gluten intolerance before adopting a gluten-free diet, as the absence of dietary fiber may pose a greater risk to gut health for many individuals.

High-Fat Diets may increase the risk of leaky gut, including their impact on tight junction proteins, bile secretion, oxidative stress, and inflammation.

Sugar and refined carbs may contribute to leaky gut, with fructose and glucose as key players, potentially triggering inflammation before leaky gut symptoms appear.

Other triggers of leaky gut include stress, alcohol, medications, and dairy products.