What Is “Leaky Gut?”

Although leaky gut is not a clinically recognized condition, intestinal permeability is associated with inflammation that can impact the digestive system and lead to disease.
what is leaky gut?

Have you recently experienced gas, bloating or other uncomfortable gastrointestinal symptoms? If so, you’re not alone. According to one study, over half of the American population experience such symptoms in a typical week. This has led to a cacophony of fad diets and catch phrases in an attempt to explain and cure such frustrating symptoms, which often evade a straight diagnosis. One of the most popular mainstream concepts is “leaky gut syndrome,” which has emerged as a catch-all self-diagnosis for general indigestion. But what is leaky gut?

Leaky gut is a controversial subject, and many clinicians refuse to recognize leaky gut as something real. But the science suggests that intestinal permeability does cause “leakage” of food particles and pathogens across the gut lining, which can be associated with serious gastrointestinal and systemic illness. In this article we’ll separate fact from fiction and hype from myth so you can understand the truth about leaky gut — and how you can avoid it.

What is leaky gut? The basics

While leaky gut is the mainstream term about which you’ve probably heard, the more accurate description is “intestinal permeability,” which occurs when the tight linkages — called tight junctions (TJs)  — that bind our intestinal cells together are compromised in some way. These TJs are critical for a healthy digestive tract because they allow nutrients and water to cross over our intestines, but keep things like bacteria and viruses out. 

TJs also play an important role in our immune responses to the things that pass through our digestive tracts, including food particles. Under healthy conditions, our intestinal cells use specialized vesicles to take in food particles or pieces of cells from our gut microbiomes. These particles are too small to elicit a full-on immune response, but they do “train” our immune systems not to react to them. It’s why healthy people don’t have allergic reactions to everything they eat.

When TJs aren’t functioning as they should, however, particles from our intestines bypass entrance into our cells and can cross directly into the body’s circulation and other tissues, eliciting system-wide inflammation and causing a range of conditions, from food allergies to more serious digestive problems and fatigue. It is this large-scale passage of particles directly across the intestinal barrier that has been coined “leaky gut,” and when you understand what’s happening, the name makes sense.

Does leaky gut cause disease?

There are several known and suspected disease associations to leaky gut, and most of them comprise a complex interplay between intestinal permeability, inflammation and disease:

  • Inflammatory bowel diseases (IBD) – Crohn’s disease and ulcerative colitis
  • Celiac disease (i.e., gluten sensitivity)
  • Obesity
  • Diabetes
  • Chronic fatigue syndrome
  • Fibromyalgia
  • Asthma

However, it is difficult-to-impossible to establish a causative role for leaky gut in any of these conditions. A major reason is that inflammation is a common driver behind both intestinal permeability and these diseases, so clinicians tend to treat intestinal permeability/leaky gut as just another symptom of disease, rather than a cause of disease. To  make matters even more complicated, many of these diseases on their own also cause (or worsen existing) intestinal permeability. We can liken the clinical attitude toward leaky gut as similar to that toward the microbiome: it’s real, and important, but whether it’s a cause or a symptom of disease remains unknown.

Nevertheless, there is some very early research that points to a possible causative relationship: intestinal permeability has been noted prior to the onset of symptoms in cases of IBD and celiac disease, for example. But until a larger body of clearer and more scientifically robust clinical research hits the scene, it is unlikely that leaky gut is going to be viewed as a serious medical condition.

So do I have leaky gut or not?

Given all of the information on the internet, it can be tempting to consider that you might have leaky gut yourself, especially if you’re suffering from some of the common gut disturbances that are typically attributed to a leaky gut. But, more likely than not, your symptoms are due to general inflammation in the gut — which, as we discussed above, is a precursor to compromised intestinal permeability. There are some key risk factors that can increase inflammation and eventually cause the intestinal lining to wear down:

If you have any of these risk factors and suffer from gas, bloating, abdominal pain, heartburn, diarrhea and/or constipation, the integrity of your intestinal barrier might be at risk. The best thing to do is to talk with your doctor, who can help you sort through the possible causes of your specific symptoms and create a treatment plan to get you on your way to better health. One of the things your doctor might prescribe, along with certain medications, is a change in diet.

Our diets: Does fat cause leaky gut?

Given that one of the major roles of TJs is to keep food particles from causing inappropriate immune responses, it should come as no surprise that a growing body of research connects diet with intestinal permeability. In fact, you may have heard that fat — specifically, unhealthy saturated fat — can cause leaky gut. As a recent scientific review summarized, there might be some truth to this:

  • Celiac disease, IBD and other gut disorders are much higher in Westernized countries (United States, Canada, and Europe) where a high-fat, low-fiber diet is common. Underlying all of these disorders is increased intestinal permeability. While the cause of this permeability remains unknown, diet does seem to be an important factor.

  • Similarly, migrants from countries with low rates of IBD moving to Westernized countries have an increased risk for IBD, which has been connected to changes in diet.

  • IBD flares — periods of increased inflammation and worsening symptoms — are linked to both increased intestinal permeability and high dietary fat consumption.
  • Dietary fats have been shown to alter the distribution and expression of proteins that comprise tight junctions, thereby impacting intestinal permeability.

  • Dietary fats can also increase bile acids, which have been associated with increased intestinal permeability and diseases such as Crohn’s (a type of IBD).

  • High-fat diets also recruit inflammatory molecules and alter the gut microbiome in ways that favor inflammation, a precursor to a disrupted intestinal barrier.

It’s important to note that the research is still early and scientists are still trying to unravel the precise mechanisms behind high-fat diets and intestinal permeability. Nevertheless, there does appear to be a connection, suggesting that certain dietary interventions could decrease GI inflammation and reduce the risk for leaky gut. In fact, according to the Cleveland Clinic, there are several dietary approaches that — while they might not address diseases associated with leaky gut — can help protect the gut against the negative effects of stress and diet, and could in turn help alleviate some GI symptoms.

How to keep your gut healthy through food

Potential therapies for minimizing gut inflammation include:

  • Probiotics: Specific probiotics are being tested for their ability to protect/support a healthy gut barrier. However, be wary of grocery store probiotics sold to support general GI health and well-being: Due to their “generally recognized as safe” status from the U.S. Food and Drug Administration (FDA), they aren’t required to undergo specific scientific studies to prove their efficacy.

  • Prebiotics: These dietary components are utilized by beneficial bacteria in our guts. By consuming prebiotics — which are found predominantly in high-fiber carbohydrate foods such as vegetables, fruits and whole grains — we are encouraging the growth and activity of bacteria that produce molecules such as short chain fatty acids (SCFAs), which play a role in maintaining a strong intestinal barrier.

  • Reduced consumption of dietary fats and sugars: Although the mechanisms aren’t fully elucidated, it’s clear that the typical Western diet, so high in unhealthy fats and sugars, is damaging to the intestinal barrier. Reducing fats and sugars, especially those found in processed foods, will pay dividends in improving your gut health. Just be sure to only reduce bad fats (i.e., saturated fats), as healthy fats such as Omega-3s and other PUFAs have plenty of health benefits.

  • A balanced diet: Variety is the spice of life — and the key to a healthy gut. A balanced diet filled with a variety of multi-colored fruits, vegetables, nuts, seeds and whole grains will provide all of the necessary micro- and macronutrients for optimal gut health and for maintaining healthy tight junctions. Adding in fish and very modest quantities of lean meats and diary foods to an otherwise healthy vegetarian-focused plate appears gut-healthy for most of us, too.

  • A low-FODMAP diet. This diet was specifically designed to help alleviate symptoms in patients with IBS, but it could also be beneficial to individuals that might have some food sensitivities and general GI discomfort. By eliminating foods that contain FODMAPs (carbohydrate molecules that interact with gut bacteria in such a way that flatulence and bloating can result), and then reintroducing them one at a time, you can identify problem foods and eliminate them from your diet while enjoying the foods that don’t exacerbate your symptoms.

Key takeaways

It is not uncommon for many of us to experience occasional symptoms of gastrointestinal distress — such as bloating, abdominal pain or other symptoms. While not necessarily a sign that you have a gut disease, these uncomfortable symptoms could represent an early warning sign that you’re suffering from gut inflammation — which could be benign or, if left unchecked, could lead to a compromised intestinal barrier and more serious issues. So if your symptoms persist, the best thing to do is visit your doctor, who can help you get to the bottom of your symptoms and get you on your way to improved gut health. In most cases, the condition isn’t serious, and lifestyle improvements such as a healthier diet (focused on fruits, vegetables and healthy fats) and better mental health (reduced stress, healthier sleep patterns) can go a long way to reducing gut inflammation and preventing a leaky gut.

Related Articles

Get insights
in your
inbox too.

Sign up for our newsletter to read
the latest in metabolic health.

Decode your metabolic health through personalized data

January’s virtual CGM analyzes your blood sugar to help you learn which foods to eat and avoid.