Digestive Permeability, commonly known as “leaky gut”, is when the small intestine’s lining becomes increasingly porous, allowing harmful substances to escape into the bloodstream.
In a healthy situation, an individual’s gut lining acts like a barricade, shielding the rest of the body from potentially harmful substances while allowing the intestines to absorb vital nutrients. However, a person with increased digestive permeability could lose nutrients and also allow bacteria, harmful waste products, and food particles to escape into the bloodstream. Digestive permeability can lead to a range of health issues, including autoimmune diseases, mental health problems, allergies, and of course digestive health issues. Understanding the factors that contribute to increased digestive permeability is essential for maintaining overall health.
The Gastrointestinal (GI) Barrier: A Quick Primer
The GI or gut barrier is crucial for protecting the body and absorbing nutrients. It lines the digestive organs, including the esophagus, stomach, and colon, and is made up of two main components – the intrinsic barrier and the extrinsic barrier. The intrinsic barrier is made up of a tightly bound system of epithelial cells. These are the primary cells responsible for ensuring the GI tract is sealed. There are varying types of epithelial cells that work to seal in the different substances that pass through the gastrointestinal tract. The epithelial cells secrete mucus, creating the extrinsic barrier. This mucus is not bound to the epithelial lining but does help maintain the barrier function of the GI barrier. Tight junctions between neighboring cells act as seals, regulating the movement of beneficial substances like water and nutrients while preventing harmful ones from passing. Dysfunction in these tight junctions can lead to “leaky gut,” causing inflammation, allergies, autoimmune issues, and even affecting the brain.
Damage to the solidity of these vital junctions can be caused by many factors. The popularity of processed foods in our culture has caused a multitude of health problems, not the least of which is leaky gut. Processed foods are high in inflammatory ingredients. Refined sugars, artificial additives, artificial preservatives, and saturated/trans fats are all inflammation causing. Chronic inflammation in the gut can cause inadequate function of tight junctions and lead to increased permeability. Processed foods are generally low in fiber and nutrients and do not support a healthy gut microbiota. This can affect the makeup of the biome and cause a disbalance of good versus bad gut bacteria which can also affect the seal of the tight junctions. Food additives like emulsifiers have been found to be irritating and cause damage to tight junctions. Examples of emulsifiers commonly found in processed foods are carrageenan and soy lecithin.
Detergents, while not intended for consumption, can sometimes contaminate food products because of packaging, manufacturing, and improper handling. This can be as simple as a dish that wasn’t thoroughly cleansed after soap application that is then used to serve food. Detergents are meant to break down fats and oils, so they can easily disrupt the lipid layer of epithelial cells that make up the GI barrier. The damage caused by detergents can cause inflammation, further disrupting the gut barrier.
A diet high in refined sugar is highly causative of gut inflammation. Refined sugar promotes the growth of bad bacteria in the gut and reduces good bacteria. Bad bacteria can release endotoxins which can cause inflammation because of the immune response the body mounts against them. Sugar can also increase cytokines in the gut microbiota. In elevated levels, cytokines lead to increased inflammation affecting the integrity of tight junctions and gut permeability.
The effect of alcohol on gut permeability is directly related to the amount consumed. The more alcohol consumed, the more affected the gut will be. Moderate consumption will have less of an effect on the gut lining, and leave tight junctions intact. Overconsumption can lead to inflammation. It can also aid the growth of harmful bacteria, offsetting good bacteria in the gut which leads to inflammation.
When alcohol is broken down, it produces substances such as acetaldehyde. Acetaldehyde can cause direct damage to gut cells and cause inflammation. Excessive alcohol consumption can damage the mucosal layer that protects the gut. All of these lead to the breakdown and failure of tight junctions.
Celiac disease is a disorder of the gut that causes the body to have an autoimmune reaction when gluten is consumed. When an affected individual consumes gluten, the immune system mounts a response to this mistaken “invader” and ultimately targets the small intestine’s lining. The damage caused to the barrier can have a large impact on the development of leaky gut. In addition to the damage of the tight junctions, it also damages the villi of the small intestine. Villi are like tiny fingers that project out of the intestinal wall. Their job is to increase surface area for nutrient absorption. Damage to the villi results in decreased surface area, malabsorption of nutrients, and overall damage to gut health from lack of nutrients. Over time, continued exposure to gluten can lead to chronic inflammation and increased incidence of leaky gut. The best thing an individual with this disease can do to begin to heal their gut is to remove gluten from their diet, thus lowering inflammation and decreasing gut barrier permeability.
In some instances, individuals may have a gluten sensitivity that is unrelated to celiac disease. Non-celiac gluten sensitivity may be identified when a person has GI symptoms after ingesting gluten but celiac disease and wheat allergy have been ruled out. Some controversy exists over whether this type of sensitivity exists, but one cannot deny a person’s claims of bloat, diarrhea, pain, constipation, and various symptoms outside the gut after the ingestion of gluten-containing foods. It has been proposed that those with this sensitivity will have a larger incidence of inflammation, thus causing increased gut permeability, but additional research is needed.
Medications and Drugs
Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) are designed to alleviate pain and inflammation. Oddly enough these anti-inflammatories can actually cause inflammation in the gut because of irritation to the GI lining, and thus increased gut permeability. When the gut lining and its protective mechanisms are compromised, the risk of ulcers increases. Gastric and duodenal ulcers add to the existing inflammation and increase the risk of leaky gut. These drugs can also increase the incidence of GI bleeding from the deteriorated GI tract. Individual sensitivities, duration of use, dosage, and type of NSAID all contribute to the likelihood of these issues. NSAIDs can cause the gut to have heightened sensitivity to other inflammation-causing things like alcohol, leading to more severe gut barrier disruption. Long-term use, overuse, and high dosages are more likely to cause problems. It is very important that individuals take them in the recommended dose and not for longer than prescribed.
Antibiotics are designed to stop bacteria. The development of antibiotics has been critical to human health through the stopping of disease and lowering of mortality rates. Whether by killing the bacteria or keeping it from reproducing, they can affect both disease-causing bacteria and good gut bacteria, lowering the diversity of gut bacteria. Because good bacteria are normally responsible for making sure pathogens do not thrive in the gut, there is an increased risk of opportunistic infections, like C. diff, to occur after antibiotic use. Because of all the disturbances to the gut microbiota that antibiotics cause, they can disrupt the gut barrier and lead to inflammation. Both are causative of increased gut permeability. It is possible after the use of antibiotics for the implications to be reversed. However, for those on long-term antibiotic therapy or repeated exposure to the same antibiotic, it is possible for the gut microbiota to never completely be restored to its pre-antibiotic state.
Infections and Pathogens
Certain bacteria, viruses, and parasites have been shown to disrupt the intestinal lining and compromise its integrity. For example, pathogenic bacteria like Escherichia coli (E. coli) and Salmonella can release toxins that directly damage the tight junctions between intestinal cells, leading to increased permeability. Similarly, some viruses, such as the norovirus, can cause inflammation and injury to the gut lining, further exacerbating the issue. Parasitic infections, like those caused by Giardia and Cryptosporidium, can also damage the intestinal barrier, making it more permeable.
Infections play a dual role in promoting leaky gut by both directly compromising the gut barrier and also by inducing inflammation. When the gut comes under attack from pathogens, the immune system triggers an inflammatory response to neutralize the invaders. However, chronic or severe infections can lead to prolonged inflammation, which, in turn, can weaken the tight junctions and increase intestinal permeability. This chronic inflammation can perpetuate the cycle of gut dysfunction and barrier impairment. Therefore, the link between infections and leaky gut underscores the importance of balanced gut microbiota, as a healthy microbiome can help protect against pathogenic invaders and maintain gut barrier integrity. Promoting a diverse and beneficial gut microbiota through a diet rich in fiber, probiotics, and prebiotics can contribute to overall gut health and reduce the risk of infection-related gut issues.
The gut-brain connection, otherwise known as the gut-brain axis, is increasingly gaining popularity in research and in understanding the way the body regulates fundamental processes and overall health. The gut-brain axis is the way in which the gut and brain communicate with one another. The vagus nerve connects the brain to the gastrointestinal tract and functions like a telephone between the two organs. This communication is also accomplished through hormones and neurotransmitters. For example, the gut makes dopamine and serotonin which influence mood. On the other hand, the brain sends messages to the gut to make digestion function. The gut houses about 70% of the body’s immune system. These cells can signal the brain which influences mood and how well the brain functions.
The other piece of the gut-brain connection is the microbiota-gut-brain axis. The network of organisms living in the gastrointestinal tract produces various compounds that affect the working order of the brain. Changes in gut bacteria have been linked to anxiety, depression, autism, and obesity. Any problems within this important circuit can affect the entire communication system.
Stress management plays a key role in the function of the gut and its microbiota, and gut issues can directly influence stress response. Chronic stress can lead to changes in the motility of the gut, causing either constipation or diarrhea. It can also make an individual have a heightened awareness of pain in the gut, which is called visceral hypersensitivity.
There is a strong correlation with stress and irritable bowel syndrome which is when an individual has high incidences of bloating, pain, and constipation/diarrhea. Stress can disrupt the neurotransmitters responsible for mood such as serotonin, making the production slow and the transmitters less active. In contrast, stress can cause the body to overproduce stress hormones (cortisol) and cause widespread inflammation in the body. Stress may reduce blood flow to the gut resulting in the inability of the lining’s tight junctions to heal and regenerate. Over time, chronic stress can lead to increased gut permeability through increased inflammation, hormones that affect the gut lining, microbiota changes, and reduced blood to the GI tract.
Zinc plays a vital role in the functionality of tight junctions in the gut barrier. Zinc supports the biochemical reactions involved in the synthesis of the proteins that compose tight junctions. Zinc, so to speak, keeps tight junctions “tight”. Zinc also is anti-inflammatory and plays a crucial part in cell division and the healing of the gut barrier. Cellular stress can weaken tight junctions, but zinc protects these from cell damage as an antioxidant. It regulates immune system response. An unregulated immune system can cause inflammation and tight junction damage. Zinc keeps it balanced. It supports the overall health of tight junction function and prevents leaky gut. It is important to be mindful of zinc levels in the body, and if they are low, consider supplementation.
Environmental stressors can play a key role in the development of leaky gut. We are assaulted from everywhere by environmental toxins. Water is “cleaned” with chemicals, the air is filled with pollution, the soil is contaminated with runoff from factories and farms, and overburdening the body. These common environmental stressors can cause gut microbiota disruptions, can cause inflammation in the gut, and can damage cells and tissues by causing oxidative stress. There are some toxins that physically break down and are toxic to the gut barrier. Repeated exposure to environmental stressors can lead to the immune system reacting to it. This can cause inflammation and lead to increased permeability. When metabolized, these toxins may break down into substances that are damaging to the gut barrier. All of these factors may lead to the leakage of harmful molecules into the blood and have widespread effects on the body as a whole. For these reasons, reducing exposure is critical to a healthy gut. Exposure may be reduced by consuming filtered water, eating a balanced organic diet, being sure to wash produce carefully, consuming probiotics, and managing stress levels.
Potential Consequences of Increased Digestive Permeability
Current research shows that increased digestive permeability can lead to systemic inflammation, food allergies/sensitivities, autoimmune diseases, and impaired absorption of nutrients. Immune response to molecules leaking out of the gut and into the bloodstream can cause inflammation. Inflammatory responses can cause cytokines to be released. These are molecules that send signals to control immune response and are inflammatory.
Chronic immune response from repeated exposure to food molecules that have escaped from the gut can cause a food allergy. The body mistakenly starts associating a particular food as an invader and mounts an allergic response against it. When the gut microbiota is balanced, it tells the immune system not to attack vital things like food.
There is a possible connection between leaky gut and the incidence of autoimmune disorders. This could be because of the immune system response that is mounted against leaking particles. It is also thought that molecular mimicry may play a role. This is when molecules that accidentally get past the GI barrier look like or share structural features with molecules in bodily tissues. When recognized as an invader, the body may mistakenly target similar bodily cells. Systemic inflammation may also be causative of autoimmune development from chronic immune response.
When the gut lining is unhealthy, undigested molecules can pass through. This leads to impaired nutrient absorption. Ideally, the tight junctions function properly and only let digested nutrients pass through to the bloodstream. Increased permeability can affect the function of the transporters that carry nutrients to the bloodstream. Disruptions in the gut microbiota can cause nutrients to not be broken down properly. Chronic inflammation can cause the enzymes needed to digest food to be sluggish. Due to damage to the mucosal layer that frequently accompanies leaky gut, the support it normally gives to nutrient absorption is compromised. It is important to note this is a complex field and not all individuals who develop leaky gut will develop widespread inflammation, food allergies, autoimmune disorders, and malabsorption.
Prevention and Restoration
Preventing and restoring a healthy gut barrier involves a multifaceted approach. First and foremost, dietary interventions play a crucial role; a diet rich in fiber, antioxidants, and nutrient-dense foods can promote gut health. Additionally, stress management is vital, as chronic stress can disrupt the gut-brain axis and contribute to leaky gut. Probiotics and prebiotics also play pivotal roles; probiotics can help maintain a balanced gut microbiota, while prebiotics nourish beneficial bacteria. Together, these strategies aim to support and protect the gut lining, ensuring optimal digestive health and overall well-being.
In conclusion, the factors contributing to increased digestive permeability, are multifaceted and can include dietary choices, chronic stress, microbiota imbalances, and environmental toxins. Recognizing the interplay of these factors highlights the importance of a holistic approach to maintaining a healthy gut. This approach involves adopting a balanced diet rich in fiber, nutrients, and probiotics, practicing stress management techniques, minimizing exposure to environmental toxins, and addressing any underlying health conditions. By nurturing the gut lining and promoting its integrity, individuals can support not only digestive health but also overall well-being.