What’s a leaky gut, and what’s ‘leaky gut syndrome’?

Leaky gut syndrome is a theoretical health condition. Mainstream medicine doesn’t currently recognize it.

The idea is that damage to the lining of your gut allows toxins or disease-causing microbes into your bloodstream, and this makes you ill. 

Supporters of leaky gut syndrome believe that it’s the cause — rather than a symptom — of different health conditions.

The lining of a healthy gut is semipermeable. It lets through water and nutrients from what you eat and drink. But it acts as a barrier against potentially dangerous bacteria and chemicals.

If you have increased intestinal permeability, larger molecules, chemicals, and microbes may pass through your gut barrier into your bloodstream.

Increased intestinal permeability is associated with conditions like inflammatory bowel diseases (IBDs), irritable bowel syndrome (IBS), and celiac disease.

Signs and symptoms

Doctors associate several symptoms with increased intestinal permeability. Still, there’s currently not much evidence that increased permeability is the cause of these issues.

Symptoms that may occur alongside increased intestinal permeability, or a leaky gut, include:

• diarrhea

• increased gas

• constipation

• abdominal pain or discomfort

• nausea or vomiting

• blood in your poop

• a fever or night sweats

• weight loss

• fatigue

Medical tests may identify other issues along with a leaky gut, such as gut ulcers or dysbiosis.

At ZOE, we run the largest nutrition science study in the world. In our research, we’ve identified 15 “good” and 15 “bad” bacteria linked with positive and negative health outcomes.

You can use our at-home test to see what levels of these bugs you have in your gut and how your body responds to certain foods. We can then give you personalized nutrition advice to help you eat the best foods for you.

Health conditions

It’s still unclear whether increased intestinal permeability, or a leaky gut, causes any other health conditions. But it’s a symptom of several gut diseases.

Here are the gut conditions associated with increased intestinal permeability:

• IBD, including Crohn’s disease and ulcerative colitis

• IBS

• metabolic syndrome

• celiac disease

• certain food allergies

• some gut infections

Several of these are autoimmune diseases, in which the immune system attacks its own cells. 

You may have heard that leaky gut syndrome causes depression, autism, and some inflammatory diseases — like arthritis, eczema, and fibromyalgia.

Right now, there’s not much evidence for these claims. Much more research is needed before scientists can come to any conclusions.

Causes

You might develop a leaky gut if the lining of your gut gets damaged.

Or, you might develop it if groups of proteins called tight junctions become disrupted. These proteins connect the cells that line your gut.

So, risk factors for developing a leaky gut include:

• a low-quality, or “Western,” diet, which is low in fiber and high in sugar and fat

• an excessive consumption of alcohol in the long term 

• overuse of nonsteroidal anti-inflammatory drugs (NSAIDs), like aspirin and ibuprofen

• inflammatory gut diseases

• food allergies

• high levels of blood fats, like cholesterol and triglycerides

• high levels of blood sugar

• insulin resistance

• obesity

• liver diseases

As we mentioned earlier, a leaky gut is also linked to dysbiosis. These issues often occur together in people with inflammatory bowel conditions. However, it’s too early to say exactly how the two are related.

But, again, picking apart what’s a symptom and what’s a cause will require much more research.

Tests and diagnosis

Because a leaky gut is a symptom of other health conditions, a doctor is more likely to test for one of those conditions than for gut leakiness, or increased intestinal permeability.

If your doctor wants to check for increased intestinal permeability, they may order one of these tests:

• Urine test: After fasting overnight, you’ll drink a solution containing two “probe molecules” of different sizes. These are usually different types of sugar. Testing your urine will show how many of the larger molecules made it through your gut lining.

• Tissue biopsy: A doctor uses a thin, tube-like tool called an endoscope to take a sample of tissue from your gut. Technicians then analyze the sample in a device called an Ussing chamber. This uses probe molecules and electrical currents to calculate your gut permeability.

• Confocal endomicroscopy: The doctor uses an endoscope to take a detailed look at your gut walls while a fluorescent liquid shows any areas that may have gaps or leaks.

• Blood test: This can show markers related to inflammation, your immune response, or antibody levels. It can indicate whether you have an illness associated with increased intestinal permeability.

Treatment

There’s no recommended treatment for leaky gut syndrome because mainstream medicine doesn’t recognize it as a diagnosis.

Treatments for illnesses associated with increased intestinal permeability vary, depending on the condition:

• IBD: People with IBD may need to take drugs that reduce inflammation or suppress the immune response. In some cases, they may need surgery to remove damaged areas of the gut.

• IBS: Treating IBS often involves changing your diet. This may involve adding probiotic foods or supplements and trying a low FODMAP diet. Doctors may also suggest support such as cognitive behavioral therapy.

• Celiac disease: If you have celiac disease, you may need to see a dietician who can help you follow a healthy gluten-free diet. This can prevent the symptoms and start to heal damage to your gut.

• Food allergies: A number of immunotherapy treatments can help reduce responses to food allergens. This might involve taking regular, small doses of the food, either by mouth or through a skin patch or injections.

Diet and leaky gut

As we’ve seen, people with celiac disease, food allergies, and sometimes IBS need to change their diets in specific ways to manage their conditions.

There are also more general nutrition strategies that may reduce intestinal permeability and support your overall gut health. 

• Switch from a Western to a Mediterranean diet: A so-called Western diet, low in fiber and high in sugar and fat, is a risk factor for increased intestinal permeability. Switching to a Mediterranean diet, which is rich in fruits, vegetables, legumes, and whole grains — and eating fewer processed foods — will boost your gut and overall health.

• Eat more prebiotics: These types of fiber and other nutrients exist in a wide range of plants. They provide fuel for your “good” gut bugs. As these bugs feed on prebiotics, they produce short-chain fatty acids, which help regulate inflammation and do a range of jobs in your body. For instance, one called butyrate provides energy to the cells of your gut lining.

• Add fermented foods: Probiotics are bacteria in certain foods and supplements, and they're good for your overall health. Regularly eating fermented foods that contain natural probiotics may help strengthen your gut barrier and improve your general gut health. 

Other ways to support your gut health

You can take plenty of other steps to improve your overall gut health:

• Get more sleep: Research suggests that better sleep is linked to a healthier and more diverse gut microbiome.

• Exercise regularly: Even low-intensity workouts can help keep your gut healthy and increase the diversity of your microbiome.

• Take antibiotics only when necessary: Antibiotics can damage your gut microbiome, so take them exactly as your doctor advises.

• Reduce stress: Stress can disrupt your gut microbiome. Here are some tips for managing stress.

• Avoid smoking: The gut microbiomes of smokers are similar to those of people with IBDs.

Another way to improve your gut health is through personalized nutrition, which the ZOE program offers.

Our program helps you understand the specific makeup of your gut microbiome and your body’s responses to different foods. With this information, we can help you choose the right foods for your gut and overall health.

If you want to learn more about how it works, take our free quiz.

Summary

Increased intestinal permeability is another name for a leaky gut.

It means that damage or disruption to your gut barrier is allowing molecules, chemicals, and microbes that wouldn’t usually make it through to enter your bloodstream.

“Leaky gut syndrome,” meanwhile, is a theoretical condition that mainstream medicine doesn’t recognize. The idea of a syndrome suggests that damage to the gut barrier is a standalone cause of illness rather than a symptom of one.

If you have a health condition associated with increased intestinal permeability, your doctor is likely to treat the condition rather than the permeability.

Some options include switching to a Mediterranean diet and adding prebiotics and fermented foods to the mix.