A gastrointestinal condition called leaky gut is gaining worldwide attention, particularly in the natural health community.

Some medical professionals deny that leaky gut exists, while others claim it is the root of nearly every health condition.

Leaky gut remains somewhat of a medical mystery. Scientists are still trying to determine exactly what it is and what causes it.

Some people think that gluten causes leaky gut, but the role of gluten in the condition is complicated.

This article examines the research about gluten and leaky gut syndrome.

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What is gluten?

Gluten is a mixture of proteins found naturally in grains like wheat, barley, and rye.

It’s responsible for the elastic nature of dough, which helps the dough hold together and rise. Gluten is also what gives bread its chewy texture (1). It’s sometimes added to bread dough to increase its ability to rise.

The two major proteins that make up wheat gluten are gliadin and glutenin. Gliadin is the part of gluten that some people have an adverse reaction to.

Summary

Gluten is a group of proteins found in wheat, barley, and rye. One of these proteins, gliadin, can cause adverse health effects in some people.

What is intestinal permeability?

The digestive system performs several very important functions in your body. In your digestive tract, your body breaks down food and absorbs nutrients into your bloodstream.

Plus, the walls of your intestines act as an important barrier between your gut and the rest of your body. The intestinal wall serves as a gatekeeper, determining which substances pass through to the bloodstream and organs.

The term “intestinal permeability” describes how easily substances pass through the intestinal wall. It’s another word for leaky gut syndrome.

Typically, there are tiny gaps between the cells in the small intestine. These gaps are called tight junctions.

If they’re are damaged or become too loose, it causes the gut to become “leaky.” This allows substances and organisms in the gut to leak into the bloodstream.

When bacteria and toxins leak into the bloodstream, it causes widespread inflammation in the body.

Increased intestinal permeability has been associated with autoimmune conditions, including type 1 diabetes, Crohn’s disease, and inflammatory skin disorders (2, 3, 4).

Summary

When the barrier function of the small intestine is impaired, bacteria and toxins can leak from the gut and may lead to inflammation and disease.

Gluten causes significant concerns for some people

Most people are able to digest gluten just fine. That said, a small proportion of people cannot tolerate it.

A serious form of gluten intolerance is called celiac disease. Celiac is a hereditary autoimmune disease.

For individuals with celiac disease, gluten can cause diarrhea, stomach pain, excessive gas, and skin rashes. Over time, it can cause damage to the intestines, which impairs their ability to absorb certain nutrients (5, 6).

However, some people test negative for celiac disease but still react to gluten. This is referred to as non-celiac gluten sensitivity.

The symptoms are similar to celiac disease, but without the autoimmune response. People with non-celiac gluten sensitivity may experience diarrhea, bloating, and gas, along with joint pain and brain fog (7).

There’s currently no clinical method of diagnosing non-celiac gluten sensitivity. If you react negatively to gluten and your symptoms are relieved with a gluten-free diet, you probably have gluten sensitivity (8, 9, 10).

The topic of gluten remains highly debated. Some medical professionals believe that gluten is harmless unless you have celiac disease. Others claim that gluten is the root cause of all kinds of health conditions and autoimmune disorders.

Summary

Most people can tolerate gluten just fine. However, gluten can cause significant concerns in individuals with an intolerance or sensitivity to it.

Gluten activates zonulin, the regulator of intestinal permeability

Several studies have shown that gluten can increase intestinal permeability and cause an immune response in the body (11).

The immune system responds to substances it recognizes as harmful by causing inflammation. Inflammation is one of the body’s natural self-protection mechanism, though persistent inflammation can be associated with multiple chronic conditions.

In individuals with a sensitivity to gluten, the protein is deemed a foreign invader by the body. This leads to inflammation.

However, there is conflicting evidence regarding gluten and intestinal permeability.

How gluten affects zonulin and gut permeability

Zonulin is a protein that regulates the tight junctions of the small intestine. When zonulin is released in the intestines, the tight junctions open slightly and allow larger particles to pass through the intestinal wall (12, 13).

Some studies have found that gluten activates zonulin, which leads to increased intestinal permeability (11, 14, 15).

One of these studies found that gluten activated zonulin in cells from individuals with and without celiac disease. However, zonulin levels were much higher in cells from people with celiac disease (14).

How does this affect people with gluten sensitivity?

Studies have consistently demonstrated that gluten significantly increases intestinal permeability in people with celiac disease (16, 17, 18).

There are mixed results when it comes to individuals without celiac disease. Test-tube studies have shown that gluten increases intestinal permeability, but this hasn’t been confirmed in human studies (17).

One clinical study also found that gluten increased intestinal permeability in people with irritable bowel syndrome (IBS) (19).

However, in other human studies, gluten did not cause any changes to intestinal permeability in those with non-celiac gluten sensitivity or IBS (20, 21).

Individual health may play a role

Gluten does activate zonulin, but it doesn’t affect everyone the same way.

It’s clear that gluten can increase intestinal permeability in those with celiac disease and possibly in those with IBS. However, it appears that gluten does not increase intestinal permeability in people without these health conditions.

Summary

Gluten activates zonulin and increases intestinal permeability in people with celiac disease. Gluten does not increase intestinal permeability in people without these health conditions.

Factors that contribute to leaky gut syndrome

Gluten may play a role in the development of leaky gut syndrome in those with celiac disease or IBS, but it’s certainly not the only cause.

Medical professionals are still trying to understand exactly what causes leaky gut syndrome. However, a few factors are known to contribute to the condition.

Some contributing factors are:

• Unhealthy diet. A diet high in fat and refined carbs may increase intestinal permeability (22, 23, 24).
• Stress. Prolonged stress can alter the gut-brain interaction and lead to all kinds of gastrointestinal issues, including increased intestinal permeability (25).
• Nonsteroidal anti-inflammatory drugs (NSAIDs). Overuse of NSAIDs, such as ibuprofen, can increase intestinal permeability (26, 27).
• Inflammation. Chronic widespread inflammation contributes to multiple chronic conditions, as well as increased intestinal permeability (28).
• Poor gut flora. When the balance between the beneficial and harmful bacteria lining the gut is compromised, it can contribute to leaky gut syndrome (2, 24).
• Zinc deficiency. A lack of zinc in the diet can alter intestinal permeability and contribute to multiple gastrointestinal concerns (29).
• Yeast. Yeast is naturally present in the intestinal tract. When the growth of yeast, mainly Candida, gets out of hand, it causes health concerns (30, 31).

Summary

Many factors contribute to the development of leaky gut syndrome. In people with celiac disease or IBS, gluten may be a contributing factor.

Should everyone avoid gluten?

Gluten causes significant health concerns for some people.

For individuals with celiac disease, gluten increases intestinal permeability and triggers an autoimmune response and inflammation.

However, the relationship between gluten and intestinal permeability is complex and not yet clearly understood.

Currently, no solid evidence supports the idea that gluten increases intestinal permeability or causes leaky gut in healthy people.

If you have symptoms of gluten sensitivity, it may be beneficial to remove gluten from your diet. You can read more about eating gluten-free here.

Summary

Those with celiac disease or gluten sensitivity should avoid gluten. However, there’s no significant evidence that people without these conditions need to avoid gluten.

Factors that can improve your gut health

One of the keys to improving your gut health and preventing leaky gut syndrome is to improve your gut flora. That means increasing the beneficial bacteria in your gut so they far outnumber the harmful bacteria.

Here are some ways to improve your gut health:

• Take probiotics. Probiotics are beneficial bacteria that can improve gut health. Probiotics are found in foods like yogurt, kefir, sauerkraut, and kimchi. They’re also available in a supplement form (31, 32, 33).
• Avoid refined carbs. Avoid sugar-sweetened beverages and foods with added sugars or refined wheat flour. The harmful bacteria in your gut thrive on these foods (22).
• Eat plenty of fiber-rich foods. Fruits, vegetables, and legumes are high in soluble fiber, which feeds the good bacteria in your gut (34, 35).

Summary

Increasing the beneficial bacteria in your gut may improve your gut health and help prevent leaky gut syndrome.

The bottom line

Gluten causes significant health concerns in individuals with an intolerance or sensitivity.

Research shows gluten can increase intestinal permeability, also known as leaky gut, in people with celiac disease and possibly IBS.

However, this does not appear to be the case for people without these conditions.

If you think you have symptoms of gluten sensitivity, it may be beneficial to talk with a healthcare professional and consider trying a gluten-free diet. However, before cutting out gluten, keep in mind that testing for celiac disease requires you to be eating a gluten-containing diet.