Gut Health

What Causes Leaky Gut: The 19 Hidden And Little Known Reasons

For many people, it can be difficult to try and find the root cause of their Leaky Gut Syndrome. This makes treatment a frustrating event that can seem to go around in circles. But, many people don't know that the root cause of their Leaky Gut Syndrome (Intestinal Permeability) could be a variety of health issues. We're going to cover the symptoms of Leaky Gut, along with 19 science-backed causes next.

Defining Leaky Gut

Leaky Gut is a broad term that many people and medical professionals use to describe a broad range of problems dealing directly with your digestive tract. However, Leaky Gut is actually a condition where small holes or cracks form in your intestinal wall. Everything you eat has an increased risk of passing through these small holes or cracks, and the bacteria that thrives in your digestive tract also passes through. (1)

Since these things are not supposed to be in your body, your immune system can view it like an infection. In response, it sends inflammation too and around your digestive tract, the inflammation can slowly spread throughout your body as the bacteria and toxins from your digestive tract spread through the cracks or holes. This is when other problems start to occur.

What Are the Signs and Symptoms of Leaky Gut?

Leaky Gut comes with several signs and symptoms that can vary in severity. They can flare up and fluctuate, and this can make your other health problems fluctuate in severity as well. Common signs and symptoms of Leaky Gut include:

  • Autoimmunity
  • Bloating
  • Brain Fog
  • Constipation
  • Depression
  • Diarrhoea
  • Eczema
  • Excessive Fatigue
  • Gas
  • Headaches
  • Immune System Issues
  • Nausea
  • Nutritional Deficiencies
  • Skin Issues

What Causes Leaky Gut: 19 Hidden and Science-Backed Causes of Leaky Gut

Several conditions can cause your Leaky Gut to get worse over time. We've rounded up the top 19 causes of Leaky Gut, and we're going to link them to scientific studies so you get a good understanding of why and how they cause this condition.

1. Large Intestinal Fungal Overgrowth

Large Intestinal Candida or Fungal Overgrowth is where specific strains of fungi start to overtake portions of your large intestine. They can cause inflammation, intestinal permeability, abdominal pain, cramping, bloating and diarrhoea. Several types of fungi are involved, and they include but are not limited to: (1)

  • Candida - There are 20 different species of Candida that can cause infections or overgrowth in your large intestine. One study took mice and purposely increased their Candida count to see if it negatively impacted the large intestine. They found that the Candida broke down the mucosal barrier and increased intestinal permeability by causing cell death and inflammation. (2)
  • Galactomyces - Another fungi in the yeast family, Galactomyces typically works to improve your skin barrier. It also naturally occurs in your intestines, usually without an issue. However, problems quickly arise if the fungus begins to overgrow. One study took people who were having common leaky gut symptoms and did a faecal test. They found that the people who were experiencing the symptoms had far higher numbers of Galactomyces than the control group. It contributes to inflammation and cell damage in your mucosal lining. (3)
2. Large Intestinal Bacterial Overgrowth

Bacterial overgrowth is more common in your large intestine than in the small intestine, simply because there is more bacteria present in the large intestine. When the conditions in your intestines create a perfect storm, bacteria levels can skyrocket. Things like chronic inflammation and damage to the cell walls like you get when you have leaky gut can encourage the "bad" levels of bacteria to outweigh the "good" ones. Common bacteria include: (4)

  • Streptococcus - Streptococcus can cause widespread inflammation throughout your digestive tract. One study took 34 healthy subjects and 34 subjects with an infection of Streptococcus and tested their intestinal permeability. They found that the infected group had more increased levels of inflammation throughout their large intestine than the control group. (5)
  • Clostridium - Clostridium is a type of bacteria that causes widespread cell death and damage because it releases toxins into your large intestine. A study showed that an overgrowth of Clostridium significantly alters the bacteria levels in your large intestine. This leads to worsening symptoms, cell inflammation and cell death, and this increased intestinal permeability. (6)

3. Small Intestinal Bacterial Overgrowth (SIBO)

Small Intestinal Bacterial Overgrowth is a condition where too much bacteria accumulates in the small intestine. Or, certain types of bacteria that typically inhabit other parts of our body start to colonise your small intestine. When this area of the gut is healthy, it doesn't contain much bacteria, so overgrowth can quickly become a problem. SIBO commonly results in more than one bacteria overgrowing and throwing off your natural "good" and "bad" levels of bacteria. (7)

One study took 20 patients and gave them the hydrogen glucose breath test to determine whether or not they had SIBO. They wanted to see how an active infection could cause intestinal permeability. All 20 of the patients tested positive, with 15 displaying peak infection levels. The researchers found that 55% of the patients with an active SIBO infection had damage to the intestinal wall, as well low-grade inflammation that prevented it from healing. (8)

4. Small Intestinal Fungal Overgrowth (SIFO)

Small Intestinal Fungal Overgrowth is a medical condition where you have an overabundance of fungal organisms present in your small intestine. People who have SIFO have an increased intestinal permeability, inflammation, bloating, gas, abdominal pain and fluctuations in their bowel movements. Although this condition is far more common in patients who have autoimmune disorders or liver disease, anyone can get it under the right conditions. (9)

One study took 19 patients with active fungal infections and compared their inflammation levels to that of 10 healthy controls. They found that the patients that had the fungal infections had higher inflammation levels, particularly if there was Candida present, compared to the control group. This inflammation level can rupture cells and prevent the cells from healing, and this leads to leaky gut. (10)

5. Celiac Disease

Celiac disease is a medical condition where you have an abnormally high sensitivity to gluten. This protein is extremely common in wheat and rye. Unless you stick to a gluten-free diet, your immune system will attack your cells and tissues. This can lead to widespread and low-grade chronic inflammation, abdominal pain, bloating, diarrhoea and damage to your intestinal walls. Unfortunately, this also means that it can make your leaky gut much worse by further damaging the cell walls and allowing more bacteria through. (11)

A study took 24 patients with untreated celiac disease, 12 patients with treated celiac disease and 10 healthy controls. They measured the inflammatory markers across all of the patients over a period of several days. They found that the patients who were on a gluten-free diet and the healthy controls had significantly reduced inflammatory markers in their blood than the untreated celiac disease patients. This constant inflammation can lead to intestinal permeability because the cell's can't heal properly from any damage. (12)

6. Non-Celiac Gluten Sensitivity

People who experience brain fog, abdominal pain, low-grade inflammation, bloating, diarrhoea, constipation, nausea or vomiting but don't have celiac disease can have a condition called Non-celiac Gluten Sensitivity. This condition results when you eat something containing gluten and your immune system is hypersensitive to it. It reacts by increasing the inflammation levels in your intestines because it sees the gluten as a "threat" that it has to eradicate. (13)

Non-celiac Gluten Sensitivity can contribute to intestinal permeability because it causes heightened levels of inflammation and tissue damage due to your immune system attacking your digestive tract to try and get rid of the gluten. One study took people with celiac disease, a control group and a group of people with Non-celiac Gluten Sensitivity and gave them a lactulose and mannitol probe to determine their levels of intestinal permeability. Researchers found that people with both celiac and Non-celiac Gluten Sensitivity had higher inflammatory markers present in their digestive tract, leading to increased intestinal permeability. (14)

7. Chronic Stress

Your stress response is how your body and brain responds to demands you place on them. These demands include things like work, school and exercise. Your stress response can push you to perform better in short-term applications. However, long-term stress or chronic stress can cause a variety of health problems, including leaky gut. (15)

Stress contributes to leaky gut by raising the levels of stress hormones present in your body. Over time, constant exposure to these hormones can damage your gut lining because your gut depends on having balanced hormone levels to function properly. A recent study showed that there were strong links between chronic stress and disruptions in your gut's intestinal barrier. The study found that participants who had chronic stress had higher concentrations of gram-negative bacteria in their digestive tract than the control group did. These gram-negative bacteria can lead to an increased immune response as your body attempts to fight off the bacteria, and this leads to high levels of inflammation. (16)(17)

Another study involving weaning pigs found that having higher amounts of cortisol in the body can alter the effectiveness of the gut lining. Researchers compared the inflammation levels and cell damage of weaning pigs who had higher cortisol levels to that of a control group. The control group had lower inflammation levels and lower intestinal permeability. (18)

8. Parasitic Infections

A parasitic infection is an infection of a living organism in your body. You can get a parasitic infection from a bug bite, sexual contact or contaminated food and water. They can wreak havoc on your body, especially in your digestive tract because this is where many of the parasites settle. Common parasitic infections include: (19)

  • Helminths - Helminths are a class of parasites that include tapeworms, roundworms and pinworms. A study showed that an active infection of Helminths could decrease the electrical impedance across your mucosal barrier. This stops the cells from functioning as they should, and it eventually led to cell death. (20)
  • Protozoa - Protozoa are single-celled organisms like cryptosporidium and giardia. Protozoa can spread and multiply in your digestive tract, and this can lead to inflammatory markers that cause damage to the epithelial walls. A study compared 39 patients with active protozoa infections to 10 healthy control patients. They found that the patients who had the infections had more inflammation, a thinner mucosal barrier and an unbalanced bacteria level when compared to the control group. (21)
9. Certain Medications

When we think of medications, we think of things that will help us overcome some form of illness or infection. However, certain medications can cause damage to your digestive tract, especially if you take them in excess. Additionally, some have side effects that can cause problems throughout your system. These medications include but are not limited to:

  • NSAIDs - NSAIDs are a class of anti-inflammatory drugs that you can get over the counter. They include medications like aspirin and Ibuprofen. If you take more than the recommended dosage, NSAIDs can cause irritation in your intestinal walls, impair how well your mucosal barrier keeps bacteria out of your system, restricts blood flow through your gastric muscles and stop the repair process. (22)
  • PPIs - PPIs are specially designed to reduce your amount of stomach acid in order to relieve your GERD symptoms. PPIs can create problems for your lower GI tract by enhancing the probability of developing ulcers. Since they're typically prescribed with NSAIDs, you could end up with holes in your digestive tract that don't heal. (23)
  • Antibiotics - Antibiotics can significantly alter the bacteria levels in your gut, and this can lead to an overgrowth of "bad' bacteria that can cause inflammation throughout your intestines. Long-term use of antibiotics can lead to chronic diarrhoea, abdominal pain, bloating and discomfort. (24)
10. Alcohol Abuse and Binge Drinking

Excessive alcohol usage and binge drinking can cause problems throughout your body. It's a very serious but preventable health problem. Binge drinking is drinking consistently until your blood alcohol concentration is at or above 0.08 grams. This can lead to severe irritation in your digestive tract. (25)

Alcohol abuse and binge drinking can lead to significant alterations of your digestive tract's mucosal lining due to functional and metabolic changes. Once this happens, your mucosal barrier will be unable to function as it should. Eventually, this damage can lead to ulcers and lesions in your stomach and intestines. It'll also bring on chronic irritation that makes it very difficult to heal these ulcers and lesions. (26)

One study demonstrated this by taking 54 patients with alcohol abuse issues, and comparing their intestinal permeability to those of 30 non-alcohol-using controls. They found that the intestinal permeability was five times higher in the alcoholic patients than in the controls, and the alcoholic patients also had higher inflammation levels. (27)

11. Dairy Consumption

Dairy products include things like milk, milk products, cheese and eggs. In many parts of the world, dairy products make up a significant part of your daily diet. But, dairy can cause issues with leaky gut, especially if you have sensitivities. (28)

One study wanted to test how dairy can cause inflammation in your digestive tract by taking 140 healthy men and women and splitting them into two groups. Group A got a dairy-rich diet for the duration of the study, and group B got a dairy-free diet for the duration of the study. Over a period of four weeks, At the end of the study, researchers found that group A had significantly increased levels of inflammation while group B had significantly decreased inflammation levels. (29)

Dairy consumption can also cause digestive problems because your body has a difficult time breaking down dairy's lactose (sugar) content. When your body can't break this down, you get inflammation, bloating, gas and abdominal pain. This inflammation prevents your cells from healing, and this leads to leaky gut. (30)

12. Poor Diet (SAD Diet)

The Standard American Diet (SAD) is a dietary pattern that is characterised by high consumption of pre-packaged food, processed meat, red meat, dairy products, eggs, corn and refined grains. This diet is historically difficult on your system, especially on your digestive tract because it contains a lot of processed and artificial ingredients that your body can't easily break down. Additionally, the higher levels of Omega-3 and Omega-6 fatty acids lead to higher inflammation levels. (31)

Research shows that there is a direct connection between the Standard American Diet and the disruption of your tight junctions in your intestines. They noted that a diet that was high in fatty acids like the SAD caused increased inflammation levels, and this inflammation activated mast cells that disrupted the normal function of the epithelial cells. (32)

Another study looked at the epithelial walls of people who ate the Standard American Diet and compared them to people who ate a balanced and healthy diet. They noted that the people who ate the Standard American Diet had a breakdown and small fissures in their intestinal barrier compared to the control group's healthy intestinal barrier. (33)

13. Radiation

Radiation is a common treatment and test for several health problems. Every time you get an MRI, CT scan or an x-ray, you have minimal exposure to radiation. Additionally, radiation therapy is a popular form of treatment for certain cancers because it shrinks tumours and kills cancer cells. However, high or repeated exposure to radiation can lead to health problems. (34)

One study showed that exposure to radiation led to changes in the small intestine in as little as two weeks after the initial exposure. Researchers exposed rats to radiation and measured their intestinal permeability for 14 consecutive days. They found that the radiation disrupted junctional proteins in the epithelium and caused a massive disorganisation that affected their ability to communicate. By day three, the rats had a significant increase in their symptoms, including their intestinal permeability. (35)

14. Sleep Disturbances and Circadian Disruptions

Your body has a 24-hour clock that it uses as an internal timing device. It features specific cells that perform a variety of functions throughout the body, notably your sleep/awake response, hormone cycles and digestion. Sleep disturbances and disruptions to this circadian rhythm can cause widespread problems throughout your body. Travel and jet lag would be a good example of having a disrupted circadian rhythm. (36)

Your circadian rhythm genes also play a direct role in regulating your intestinal barrier. Research has found that circadian rhythm disruption involving mice through environmental factors or genetics significantly increased their intestinal permeability because their circadian rhythm wasn't able to perform as it normally would due to the disruptions. This led to increased inflammation, a breakdown of the epithelial wall and small fissures or cracks. (37)

Additionally, sleep disturbances can influence the amount of inflammatory cytokines that your body releases into your digestive tract. Studies have found that people who had sleep disturbances had higher levels of inflammatory markers, and this influences how well the digestive tract functions and heals from fissures or cracks. (38)

15. Low Microbial Diversity (Limited Gut Species)

People who have limited species of bacteria in their gut are more prone to having problems with leaky gut. If you have a higher amount of fungi species present in your digestive tract, they can cause a reduction in the number of bacteria. This makes it more difficult for the bacteria in your gut to stay in balance with one another, and it's common to see increased intestinal permeability or digestive issues in general. (39)

Although research in this area is relatively new, it's starting to form links between a reduced level of gut species and chronic, low-grade inflammation. The bacteria aren't able to find a balance between "good" and "bad" levels, and your immune system sends inflammation to try and reduce the "bad" bacteria. This leads to chronic irritation or inflammation of your digestive tract. Eventually, this chronic inflammation can turn into cell damage, and your cells won't be able to start the healing process. This is when you get the fissures or cracks associated with leaky gut. (40)

16. Heavy Metal Toxicity

Heavy metal toxicity is a condition that results from exposure to heavy metals that starts to negatively impact your everyday life. You can get exposure to heavy metals at your work, home, through your diet or medications. Common heavy metals that cause intestinal permeability include: (41)

  • Mercury - Mercury is quickly and easily absorbed in your gut, and it causes a disruption with the cells that line your intestine. Excessive exposure can cause significant disruptions in your mucosal layers. (42)
  • Lead - Exposure to lead can disrupt the bacteria levels in your gut. This can cause inflammation that further complicates your gut dysbiosis. This means that your intestinal permeability will get worse as your exposure to lead goes on. (43)
  • Arsenic - Arsenic is another heavy metal that can lead to a disruption in the bacteria levels in your digestive tract. These altered bacteria levels can cause low-grade inflammation that spreads throughout your digestive tract and makes it difficult for your mucosal lining to heal from any fissures or cracks. (44)

17. Mould Toxicity

Mould toxicity, or any mould-based illness is often overlooked by medical professionals because it's more uncommon. It can manifest in a variety of different ways, including psychiatric with depression and anxiety, or physical with brain fog and leaky gut. Mould toxicity comes about due to excessive exposure to mould spores. This can happen in your home if you live in damp and humid conditions, in the surrounding environment or at work. (45)

Moulds leave behind mycotoxins, and these particles play a critical role in your development of chronic inflammatory response syndrome. This syndrome can impair your gut's health on both a functional and structural level. First, it can alter the bacteria levels in your gut to give you a higher level of "bad" bacteria and a lower level of "good" bacteria. Second, it can weaken the protein bonds between your epithelial cells. When this happens, it decreased the level of mucus production, and this weakens your intestinal barrier. (46)

18. Drinking Tap Water

Did you know that your tap water contains chemicals that can irritate your digestive tract? Two of the most common chemicals found in tap water are fluoride and chlorine. Chlorine is effective at killing of certain strains of bacteria, and fluoride can help to strengthen the enamel of your teeth and prevent tooth decay. (47)(48)

Studies show that chlorine and fluoride can alter your bacteria levels in your gut. They can kill both good and bad bacteria without discriminating between the two. Studies took two groups of mice and gave one water with fluoride and chlorine, and gave the control group purified water. They found that the mice who received the non-purified water had significantly altered bacteria levels, and this can lead to inflammation and cell damage, or leaky gut. (49)

19. Vitamin D Deficiency

Vitamin D is essential for calcium absorption, reducing inflammation and for promoting good bone health throughout your life. (50)

One study took patients with lower vitamin D levels and split them into two groups. One group received a vitamin D supplement each day of the trial, while the other group received a placebo. They measured the levels of inflammatory markers in blood samples from both groups. At the end of the study, they found that the group who received the vitamin D supplement had significantly less inflammatory markers compared to the placebo group. This shows that a vitamin D deficiency can lead to increased intestinal permeability and higher inflammation levels. (51)

Bottom Line

Leaky Gut Syndrome can come from many different sources, and it routinely goes unnoticed. However, you should talk to your physician if you believe that you have this condition. They could perform tests and start you on a treatment plan that can help not only your leaky gut, but the underlying condition as well.

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