Leaky Gut Syndrome

What is leaky gut syndrome?

Leaky gut syndrome is a hypothetical condition. It’s based on the concept of relative intestinal permeability.

Intestinal permeability

Everyone’s guts are semi-permeable. The mucous lining of our intestines is designed to absorb water and nutrients from our food into our bloodstream. But some people have increased intestinal permeability or hyperpermeability. That means their guts let more than water and nutrients through — they “leak”.

Studies have shown that people who have certain chronic gastrointestinal diseases have leaky guts that let larger molecules through — potentially toxic ones. Part of the job of your intestinal lining is to act as a barrier to bacteria and other infectious agents inside the gut. This barrier is an important agent in your immune system.

“Leaky gut syndrome”

Leaky gut syndrome is a theory that intestinal permeability is not only a symptom of gastrointestinal disease but an underlying cause that develops independently. If your intestinal barrier is impaired, it may be letting toxins into your bloodstream. These toxins may trigger an inflammatory response that may manifest as various diseases.

The theory has some appeal as a way of explaining various conditions that we haven't been able to fully explain yet, but the evidence is lacking. We know that the condition of having intestinal permeability or a “leaky gut” is real, but we don’t know that it's a disease in itself, or that it causes other diseases. It’s not currently a recognized medical diagnosis.

What disease is associated with leaky gut?

There are diseases that are known to be associated with intestinal permeability, and there is a lot of speculation about other possible diseases that might be connected to it.

Known disease associations

Intestinal permeability is a recognized feature of several inflammatory and autoimmune diseases affecting the digestive system, including inflammatory bowel disease and celiac disease. In these cases, scientists generally consider it to be a symptom, not a cause. These diseases cause chronic inflammation in the intestines, which leads to erosion of the intestinal barrier gradually over time.

There have been cases where scientists found intestinal permeability in people before they were diagnosed with these diseases. This has led to some speculation that intestinal permeability might develop independently from these diseases, and might even be a contributing cause. But scientists concluded that intestinal permeability in these cases wasn’t enough to cause the disease by itself. It was more likely to be an early sign of disease.

Possible disease associations

Many other diseases have been suggested as possible consequences of leaky gut syndrome. The idea is that “toxins” from your intestines may leak into your bloodstream and cause an inflammatory response. Chronic low-grade inflammation may, indeed, be a factor in many of these diseases, including metabolic disorders such as obesity and diabetes, arthritis, chronic fatigue syndrome, asthma and fibromyalgia. But the rest remains unclear.

Scientists have measured higher levels of gut bacteria products in the blood in people with gastrointestinal (GI) diseases that are known to cause intestinal permeability. In these cases, inflammation is primarily from other causes, though bacteria products could make it worse. They’ve also measured it in liver disease, which is directly related to the gut. Bacteria products traveling from the gut to the liver via the portal vein could contribute to liver disease, but is not necessarily the cause of it.

Who does intestinal permeability affect?

The known causes of intestinal permeability involve systematic erosion of the intestinal lining. This is not a simple feat. Your intestinal lining has many layers of defense. And while it can be injured temporarily, it is designed to constantly repair and replenish itself. To actually wear it down enough to penetrate the lining requires a significant assault. That usually means a chronic disease, chronic drug use or alcohol abuse or radiation therapy.

The theory of leaky gut syndrome suggests that anything that injures your gut lining can lead to intestinal permeability if the injury is persistent enough. Therefore, common everyday factors such as diet and stress may cumulatively wear down your intestinal lining until it becomes permeable. Scientists aren’t sure about this, but they do agree that these everyday factors may cause inflammation in your gut lining and uncomfortable GI symptoms for you.

How does a leaky gut affect my body?

Erosion of your intestinal lining is one thing, and intestinal permeability is another. Most people who think they may have a leaky gut have certain common gastrointestinal symptoms, such as abdominal pain, food sensitivities, bloating and indigestion. These types of symptoms are common and may have many possible explanations, and many of them may injure your intestinal lining. You don’t have to have a leaky gut to experience those effects.

Erosion of the intestinal lining

If your gut lining is under constant assault, eventually it won’t be able to fend off erosion by chemical irritants, abrasive particles or bacteria inside your gut. This is what happens in peptic ulcer disease and SIBO (small intestinal bacterial overgrowth). The wrong kind of bacteria overwhelms the other bacteria that would usually balance them. The erosive acids and enzymes in your gut overwhelm the protective mucus that usually neutralizes them.

Erosion of your gut lining will affect your digestion, your immunity, and your sensitivity to pain in your intestines. And in some cases, it may lead to intestinal permeability. But it doesn’t have to go that far for you to feel unwell. If you have gastrointestinal symptoms, these are likely related to the underlying condition that would be injuring your intestinal lining in the first place. Many gastrointestinal diseases share these same symptoms.

Intestinal permeability

Some people do have increased intestinal permeability, but it’s difficult to separate symptoms of intestinal permeability from the inflammation that precedes it. When your gut lining is more permeable, bacteria living in your gut could cross the intestinal barrier, but we don’t know if this does significant harm separate from the original disease or injury that caused it. Some studies suggest that bacteria products traveling from the gut to the liver may contribute to liver disease.

What is the main cause of a leaky gut?

If your intestinal barrier has been breached, it has been under significant assault, probably for some time. The most direct causes of intestinal permeability include:

• Chronic inflammatory states, such as IBD and celiac disease.
• Other diseases that cause intestinal injury, such as HIV/AIDS.
• Chemotherapy and radiation therapies that degrade the intestinal mucosa.
• Chronic overuse of alcohol or NSAIDs, such as aspirin and ibuprofen.
• Food allergies that cause an immune response to certain foods.

What are the symptoms of a leaky gut?

There are no symptoms associated directly with intestinal permeability. But intestinal permeability usually follows from injury to your intestinal lining, and you may have symptoms from that.
For example:

• A burning feeling of ulceration in your gut.
• Painful indigestion from the loss of intestinal mucosa.
• Diarrhea
• Gas and bloating from fermentation by overgrown bacteria in your gut.
• Low energy from the reduced ability to draw energy from your food.
• Gastrointestinal mucositis from radiation therapy.

How is intestinal permeability measured?

There is no standard test to measure intestinal permeability directly in patients, which is one reason why intestinal hyperpermeability is not a current medical diagnosis. However, there are several kinds of tests currently under investigation in clinical research to look for evidence of intestinal permeability in patients. Tests include:

• Urine test. For this test, you drink a solution containing different kinds of sugars with molecules of different sizes, some of which are not usually absorbed in the intestines. Then analysts measure the sugar levels in your urine to see which ones made it through your gut wall.
• Blood test. This test analyzes a sample of your blood for evidence of gut bacteria infiltration. Specific antibodies and endotoxins are some of the biomarkers analysts look for.
• Tissue biopsy. This more invasive test examines a sample of your intestinal tissue in something called an Ussing chamber. The test uses electrical current to measure ion transport across the intestinal barrier. The ion transport measurement is parallel to water transport.
• Confocal endomicroscopy. This is an enhanced endoscopy exam that allows scientists to look at your intestinal lining in high resolution and magnification. A contrast fluid injected into your vein may show up in your gut if there is a gap in the lining.

What is the fastest way to heal leaky gut?

The only known cure for a leaky gut is to treat the underlying condition that causes it. Specific treatments for IBD, celiac disease and others associated with intestinal permeability have been shown to repair the intestinal lining in those who were affected. On the other hand, treatments that target the intestinal lining independently have not been shown to improve these diseases or prevent intestinal permeability from recurring.

How can I take care of my gut?

Scientists are continuing to investigate the benefits of various therapeutics for improving the general health and integrity of the gut lining. These therapies may not be able to mitigate a pathological disease, but they may help mitigate the effects of everyday factors such as diet, stress and bacterial overgrowth that can wear on your intestinal lining. They may even help alleviate your general gastrointestinal symptoms. Therapies include:

• Probiotics. Specific probiotics are being tested separately for their ability to restore gut barrier function. But in general, probiotics may help maintain the health of your gut lining by preventing overgrowth of the wrong bacteria in your gut, especially your small intestine.
• Prebiotics. Prebiotics are food for the good bacteria in your gut to help give them an edge in the fight. They are usually plant fibers — one more reason to eat your veggies.
• Reduce dietary fats and sugars. These encourage the growth of the wrong kinds of gut bacteria, and they trigger the release of harsh dietary emulsifiers that may inflame your gut.
• Nutrition. A balanced diet, complete with all the necessary macronutrients and micronutrients (vitamins and minerals) can help fortify your gut. Vitamin D and an amino acid called L-glutamine may specifically help repair your gut lining.
• Low FODMAP Diet. This specific diet is often suggested for people who have IBS and certain food sensitivities because it systematically eliminates most of the common food triggers. Using it briefly may give your gut the rest it needs to repair, while also clueing you in to which food triggers you are sensitive to.

A note from Cleveland Clinic

Many people have vague gastrointestinal symptoms, and many times the causes are frustratingly elusive. In the absence of straight answers, “leaky gut syndrome” has emerged in the mainstream as a catch-all diagnosis for general indigestion — and possibly many other conditions. But true intestinal hyperpermeability is too specific and too extreme to explain most people’s symptoms.

Most people simply have general gut inflammation — the precursor to intestinal permeability. This may be due to a specific disease, or it may be a cumulative effect of poor diet, chronic stress and other common factors. Try reducing these factors. If that doesn’t help, seek medical advice. A qualified gastroenterologist can help you sort through the possible causes of your specific symptoms.