By Becky Bell

A phenomenon called "leaky gut" has gained quite a bit of attention lately, particularly among natural health enthusiasts.

Leaky gut, also known as increased intestinal permeability, is a digestive condition in which bacteria and toxins are able to "leak" through the intestinal wall.

Mainstream medical professionals do not recognize leaky gut as a real condition.

However, there is quite a bit of scientific evidence that leaky gut does exist and may be associated with multiple health problems.

This article takes a critical look at the evidence on leaky gut syndrome.

What Is Leaky Gut?

The human digestive tract is where food is broken down and nutrients are absorbed.

The digestive system also plays an important role in protecting your body from harmful substances. The walls of the intestines act as barriers, controlling what enters the bloodstream to be transported to your organs.

Small gaps in the intestinal wall called tight junctions allow water and nutrients to pass through, while blocking the passage of harmful substances. Intestinal permeability refers to how easily substances pass through the intestinal wall.

When the tight junctions of intestinal walls become loose, the gut becomes more permeable, which may allow bacteria and toxins to pass from the gut into the bloodstream. This phenomenon is commonly referred to as "leaky gut."

When the gut is "leaky" and bacteria and toxins enter the bloodstream, it can cause widespread inflammation and possibly trigger a reaction from the immune system.

Supposed symptoms of leaky gut syndrome include bloating, food sensitivities, fatigue, digestive issues and skin problems (1).

However, leaky gut is not a recognized medical diagnosis. In fact, some medical professionals deny that it even exists.

Proponents claim that it's the underlying cause of all sorts of conditions, including chronic fatigue syndrome, migraines, multiple sclerosis, fibromyalgia, food sensitivities, thyroid abnormalities, mood swings, skin conditions and autism.

The problem is that very few scientific studies mention leaky gut syndrome.

Nevertheless, medical professionals do agree that increased intestinal permeability or intestinal hyperpermeability, exists in certain chronic diseases (1, 2).

Summary: Leaky gut or intestinal hyperpermeability, is a phenomenon that occurs when the tight junctions of the intestinal wall become loose, allowing harmful substances to enter the bloodstream.

What Causes Leaky Gut?

Leaky gut syndrome remains a bit of a medical mystery and medical professionals are still trying to determine exactly what causes it.

A protein called zonulin is the only known regulator of intestinal permeability (3, 4).

When it's activated in genetically susceptible people, it can lead to leaky gut. Two factors that trigger the release of zonulin are bacteria in the intestines and gluten, which is a protein found in wheat and other grains (3, 4, 5).

However, some studies have shown that gluten only increases intestinal permeability in people with conditions like celiac disease or irritable bowel syndrome (6, 7).

There are likely multiple contributing factors to leaky gut syndrome.

Below are a few factors that are believed to play a role:

• Excessive sugar intake: An unhealthy diet high in sugar, particularly fructose, harms the barrier function of the intestinal wall (8, 9).

• Non-steroidal anti-inflammatory drugs (NSAIDs): The long-term use of NSAIDs like ibuprofen can increase intestinal permeability and contribute to leaky gut (10, 11, 12).

• Excessive alcohol intake: Excessive alcohol intake may increase intestinal permeability (10, 13).

• Nutrient deficiencies: Deficiencies in vitamin A, vitamin D and zinc have each been implicated in increased intestinal permeability (8, 14, 15).

• Inflammation: Chronic inflammation throughout the body can contribute to leaky gut syndrome (16).

• Stress: Chronic stress is a contributing factor to multiple gastrointestinal disorders, including leaky gut (17).

• Poor gut health: There are millions of bacteria in the gut, some beneficial and some harmful. When the balance between the two is disrupted, it can affect the barrier function of the intestinal wall (1, 8).

• Yeast overgrowth: Yeast is naturally present in the gut, but an overgrowth of yeast may contribute to leaky gut (18).

Summary: Medical professionals are still trying to determine what causes leaky gut syndrome. An unhealthy diet, long-term NSAID use, stress and chronic inflammation are some factors that are believed to contribute to it.