The Term ‘Leaky Gut’ Is All Over The Internet—But What Exactly Is It?

The more we learn about the gut, the more we realize the vital role it plays in our overall health. After all, much of our immune system lives in our GI tract, meaning our gut plays a big role in our ability to respond to harmful bacteria, toxins, and more.

Here’s how it works: The lining of our gut acts as a barrier, allowing some of the substances we ingest (like water, vitamins, and minerals) to enter the bloodstream, and blocking others so they pass through and exit our system, according to a review published in the Journal of Allergy and Immunology.

When this barrier doesn’t function properly, though, those harmful particles are able to get through, into the bloodstream, and causing a domino effect of issues as the immune system responds to the intruders. Experts refer to this reduced function of the gut barrier as ‘intestinal permeability,’ but you probably know it by a term that seems to have taken over the internet: leaky gut.

How And Why Exactly Does A Gut ‘Leak’?

The gut has a few layers that help keep harmful substances out of the bloodstream, but a lot of the action related to leaky gut happens on what’s called the epithelial cell layer. “Between these cells are structures called ‘tight junctures’ that act like gates between the gut and the bloodstream,” says Patrick Okolo, M.D., Chief of Gastroenterology at Lenox Hill Hospital in New York City.

In a normally-functioning gut, these structures are ‘tight’ enough to block out larger molecules. When tight junctures open up, though, they allow potentially harmful molecules into the bloodstream, and the body reacts by triggering an inflammatory response, Okolo says. Basically, your body goes into attack mode, which can lead to (or worsen) autoimmune disorders like celiac disease, rheumatoid arthritis, thyroid conditions, Crohn’s disease, or IBS, to name a few.

But how does this gut barrier get ‘leaky’ in the first place? It all starts with genetics, and additional stresses put on the GI system (like bacterial overgrowth or exposure to triggers like alcohol, NSAIDs, or foods we’re allergic to) can weaken that barrier function further, according to a review published in the Journal of Clinical Gastroenterology.

Related: 4 Types of Foods That Help Fight Inflammation

What Can You Do About ‘Leaky Gut’?

If your intestinal permeability is off, your symptoms will reflect the GI and immune systems being affected. “Common symptoms patients report include abdominal pain, fatigue, chills, and diarrhea,” says Christine Frissora, M.D., associate professor of clinical medicine at the Weill College of Medicine of Cornell University. If any of these symptoms sound familiar, see a gastroenterologist who can properly test for issues like an autoimmune disease (such as celiac disease or Crohn’s), a food allergy, or gastrointestinal disease (such as IBS).

While there’s no comprehensive test that evaluates the gut’s barrier function, a protein called zonulin seems to open and close the tight junctures in the gut barrier, says Okolo—and a review published in Clinical Reviews of Allergies & Immunology notes that excess zonulin has been found in people with autoimmune conditions.

Since there’s no medication that can whip a leaky gut back into shape, supporting overall gut health and treating a related GI or immune conditions is your best bet for tightening up those tight junctures and improving your gut’s barrier magic.

Your doc will work with you to eliminate any allergy-inducing foods, diagnose and/or treat GI or immune conditions, support gut flora with prebiotics and probiotics, and improve overall nutrition, says Okolo.

Just beware leaky gut hysteria that suggests even neurological conditions like autism result from not-so-tight tight junctures, says Okolo. While there’s research and credible literature to support the role of gut permeability in digestive and immune issues, there’s no evidence that its effects go beyond that, he says.

Related: Check out a variety of supplements that promote gut health.

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