What is Leaky Gut - Dr. Michael Ruscio, DC

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Do you want to start feeling better?

Yes, Where Do I Start?

What is Leaky Gut

How to identify and heal leaky gut.

Key Takeaways

  • Leaky gut, also called “intestinal permeability”, is a loosening of the tight junctions between the cells that line your small intestine.
  • There are several diet and lifestyle factors, as well as infections that can increase digestive symptoms, intestinal permeability and leaky gut. These include inflammatory foods, alcohol, lack of sleep, stress, alcohol and NSAID (non-steroidal anti-inflammatory drugs) use, and antibiotics.
  • Leaky gut syndrome can cause a wide variety of symptoms across many different body systems.
  • If you have digestive disorders or gut health problems, you can generally assume that you have a leaky gut.
  • Though it’s unclear whether leaky gut is a cause or an effect health conditions, we do know that reducing intestinal permeability leads to symptom improvement.
  • Evidence suggests an association between leaky gut and some autoimmune diseases.
  • There are three main strategies to improve leaky gut: Diet changes, habit changes, and key supplements.

What is Leaky Gut?

Leaky gut, also called “intestinal permeability”, is a loosening of the tight junctions between the cells that line your small intestine.

Leaky gut is a big deal because it can lead to a litany of chronic inflammatory conditions that cause pain, discomfort and disability. Leaky gut symptoms often include mystery symptoms such as brain fog and joint pain.

Let’s look at this process in more detail:

  • The cells of your small intestine normally maintain a barrier that allows only digested food molecules through.
  • When the tight junctions loosen, much larger molecules, such as undigested food particles and bacterial fragments enter your bloodstream.
  • The immune system does not recognize these large particles and launches an immune response.
  • This overzealous immune response leads to inflammation in the gut and/or elsewhere in the body.

You may have heard of a protein called Zonulin. Zonulin increases with bacterial overgrowths or gut infections and is currently the only known biochemical driver of leaky gut. [1]

Though leaky gut syndrome is not yet recognized by the medical community as a diagnosis, intestinal permeability is widely acknowledged in research. Gastroenterologists associate Intestinal permeability with a wide variety of health problems, including IBS, IBD, some autoimmune diseases and Type 1 Diabetes.

What Causes Leaky Gut?

Diet and lifestyle factors can increase intestinal permeability and leaky gut symptoms. Gut infections are also a recognized cause.

Here is a summary of the most common causes of leaky gut:

Poor Diet and Inflammatory Foods

Sugar, alcohol, and some processed foods generally increase inflammation and intestinal lining damage, or may feed bad gut bacteria, which can lead to increased gut damage and leaky gut. And though these foods are often inflammatory, any food that you have a food sensitivity or food allergy to can continue to encourage leaky gut.


Stress increases cortisol and other stress hormones which can contribute to leaky gut. Chronic stress can make it difficult to resolve your leaky gut and other gut health issues. [2, 3] This includes chronic stress from over-exercising or over-training. [4]

Poor Sleep

A chronic lack of sleep (either poor sleep or too little sleep) can impact your gut health and lead to intestinal permeability.[5]


The use of antibiotics can negatively affect your beneficial bacteria populations, which can lead to leaky gut, and can leave you vulnerable to opportunistic infections. [6]

Alcohol, NSAIDs, and Prescription Medications

Regular alcohol consumption, use of NSAIDs (nonsteroidal anti-inflammatory drugs) and aspirin, and some prescription medications have been shown to increase intestinal permeability. [7, 8, 9]

Intestinal Dysbiosis and Infections

Intestinal dysbiosis, whether from an overgrowth of bacteria, or parasites or fungi, are a well-recognized contributor to leaky gut by triggering the release of zonulin, and reducing the protective mucous layer in the large or small intestine. [10, 11, 12, 13]

Symptoms of Leaky Gut

Leaky gut syndrome can cause a wide variety of symptoms across many different body systems.

Digestive disorders, such as bloating, gas, gut pain, or frequent diarrhea or constipation are symptoms of leaky gut, and indicate leaky gut is present and needs to be addressed. There is also evidence that symptoms such as brain fog, joint pain, fatigue (especially after eating), and food sensitivities may be associated with leaky gut. Here is a summary of symptoms that may indicate you have leaky gut.

Body System Leaky Gut Symptoms Research
Digestive Bloating, abdominal pain, IBS, colitis, Crohn’s, IBD 14,15,16,17
Brain/Neurological Mental Health Conditions such as Depression, Anxiety, Brain Fog, Pain Syndromes 18,19,20,21,22,23, 24, 25, 26, 27
Energy Production Fatigue (especially after meals), Chronic Fatigue 28,29,30
Joints Joint Pain, Inflammation 31,32,33
Skin Acne or Lesions 34,35,36,37
Immune System Autoimmune Disorders like Thyroid, Rheumatoid Arthritis, Celiac, Fibromyalgia, Food Allergies 38,39,40,41,42, 43, 44
Cardiovascular Arterial Inflammation 45
Blood History of Anemia 46,47

How to Know if You Have Leaky Gut 

Lab tests for intestinal permeability measure zonulin in blood or stool, or lactulose-to-mannitol ratio in urine. These lab tests aren’t well validated in the research, although blood testing for zonulin antibodies seems to provide some relevant information.

I generally don’t find these tests clinically valuable or to be a good use of my patients’ health care dollars. If you have digestive disorders or gut health problems, you can generally assume that you have a leaky gut.

As you work to heal your leaky gut, inflammation will reduce and your symptoms will improve as well. That’s how you know your leaky gut is healing.

What Does Science Say About Leaky Gut?

Leaky gut isn’t yet recognized as a distinct condition in the scientific literature or by the medical community, but intestinal permeability is widely researched. Despite the fact that leaky gut isn’t a specifically defined condition, this doesn’t mean it’s not real and can’t be addressed.

  • Intestinal permeability has been documented in many diseases such as celiac disease, inflammatory bowel disease (IBD), Type 1 Diabetes, food allergies, irritable bowel syndrome (IBS), Crohn’s disease, and even cardiovascular disease. [48, 49, 50, 51, 52, 53]
  • In celiac and Crohn’s disease, increased intestinal permeability is associated with an increase in symptoms such as brain fog, mood changes, skin lesions, chronic fatigue syndrome, and gut symptoms.

Most studies have been unable to tell which came first, the leaky gut or the diagnosis. Though it’s unclear whether leaky gut is a cause or an effect of health conditions, we do know that reducing intestinal permeability appears to lead to symptom improvements.

Is Leaky Gut the Cause of Autoimmune Diseases?

Many in the alternative medicine community claim that leaky gut is the root cause of all autoimmune diseases.

While there is some evidence to suggest an association between leaky gut and some autoimmune diseases, there is not yet enough evidence to say all autoimmune disease is caused by leaky gut.

Some studies link certain autoimmune diseases like celiac disease, Crohn’s disease, and rheumatoid arthritis with intestinal permeability. 

  • In one study, Crohn’s disease patients and their close relatives were evaluated for intestinal permeability. The relatives showed evidence of intestinal permeability, even though they were asymptomatic, indicating that leaky gut may precede the development of Crohn’s intestinal symptoms.[54]
  • In several animal studies, intestinal permeability was shown to occur before the development of disease. [55, 56, 57]

More research is needed to fully understand these and related phenomena. But the bottom line is that there is not currently enough data to suggest that ALL autoimmune disease is caused by a leaky gut.

How to Improve Leaky Gut

Whether you have autoimmune disease, chronic inflammation, or annoying symptoms, there is plenty you can do to improve your gut health. Anything you do to improve your gut health will also help with leaky gut.

There are three main strategies to improve leaky gut:

  1. Diet Changes
  2. Habit Changes
  3. Key Supplements

Diet Changes

If your skin reacts to a deodorant you’re using, you wouldn’t go get a prescription for cortisone cream. You would find a different deodorant that didn’t cause a reaction!

It’s much the same with diet. If you continue to eat foods your body is sensitive to, you continue to create inflammation and irritation. Improving your diet is one of the most important steps you can take for gut health.

There are several anti-inflammatory diets that could be a good leaky gut diet plan for you. The right one for you is the one your body responds to best. Here is a summary of the diets that have been shown to improve intestinal permeability:

Diet How it Heals Leaky Gut
Gluten-Free Diet Decreases zonulin and FODMAPs.
Low FODMAP Diet Decreased fermentable carbohydrates that may be irritating your gut by feeding gut bacteria.
Paleo Diet Decreases processed foods, dairy, sugar, and carbs. Emphasizes a whole-foods, low-carb diet high in veggies, healthy fatty acids like coconut oil and avocado, and healthy protein.
Fasting/Intermittent Fasting Gives your gut a rest to decrease inflammation and allow healing.
Elemental Diet Gives your gut a rest to decrease inflammation and allow healing.

Working with a nutritionist may help you find the right diet to use faster. You can read more about improving your diet for leaky gut in Leaky Gut Diet Plan.

Habit Changes

Simple changes to your daily habits can significantly improve leaky gut. You don’t need to necessarily do ALL these things to experience a benefit. Chances are there are one or two of these options that you know are most out of balance.

Habit Change Why It’s Important
Regular Moderate Exercise Over-exercise can increase leaky gut [58, 59], while regular moderate exercise has been shown to decrease inflammation. [60]
Increase Nightly Hours of Sleep Decreased sleep is associated with increased intestinal permeability. [61]
Improve Your Stress Management Psychological stress has been shown to increase leaky gut. [62, 63]
Reduce Alcohol Consumption Alcohol consumption can increase leaky gut. [64, 65]
Chew Your Food Well Complete chewing decreases stress on your digestive system, and promotes more complete digestion.
Use Alternatives to NSAIDs and Aspirin Several studies clearly demonstrate that NSAIDs and aspirin increase intestinal lining damage and leaky gut. [66, 67, 68]
Use Alternatives to Birth Control Pills for Contraception Birth control pills may negatively affect the gut microbiome, and increase the risk for Inflammatory Bowel Disease (IBD) and other digestive problems. [69]

Supplements to Heal Leaky Gut

There are lots of supplements that benefit the gut barrier and gut health. Here are the top three I encourage you to start with:

  • Probiotics improve the health of the gut microbiota  and help to maintain a healthy intestinal barrier, while an overgrowth of bad gut flora or bacteria, such as SIBO (Small Intestinal Bacterial Overgrowth) can lead to increased intestinal permeability. [70, 71, 72, 73]
  • L-Glutamine is an amino acid that has a significant body of research showing its restorative properties for the gut lining, especially during stress. [74, 75]
  • Vitamin D seems to help maintain immune system balance in the gut and prevent gut health problems.

Other supplements, like digestive enzymes, prebiotics, zinc carnosine, and more may be helpful, but may not be as necessary as probiotics, L-glutamine, and vitamin D.


Leaky gut, a loosening of the tight junctions between the cells of the small intestine, may sound a bit complicated. But the simple truth is that eating well, maintaining good health habits with sleep, stress, and exercise, and a few key supplements can begin to restore your intestinal wall barrier within a matter of weeks and can lead to rapid symptom improvement.

Though there isn’t yet enough evidence to claim that all autoimmune diseases are caused by leaky gut, we do know that many medical conditions and distressing symptoms can be improved by taking a few simple steps to improve gut health.

For more about how to heal your leaky gut, see How to Heal Leaky Gut.

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