What is leaky gut? And how does it impact autoimmune disease?

How increased intestinal permeability can influence many health conditions including

chronic disease and autoimmune disease. 

Gut health is a pretty big topic in the health and wellness world at the moment.

With many people beginning to understand the impacts gut health can have on the way we feel, symptoms we are putting up with, and our health overall. With ever expanding research looking into the relationship between our gut, diet, gut microbiome, and the influence these have on both our physical and mental health.  

What we eat and what we do, diet and lifestyle factors, can influence our gut health and intestinal permeability. 

Increased intestinal permeability, more commonly called leaky gut, can lead to a range of unpleasant symptoms, both to do with our gut and the rest of our body. This increased intestinal permeability can contribute to the development or severity of autoimmune disease, chronic inflammation and many other health conditions, presenting in many different ways for different people. 

What is intestinal permeability? 

Our gastrointestinal system (digestive system) has developed so that we can absorb nutrients and be protected from foreign components that we don’t want or need in our bodies. The intestinal epithelial barrier lines our intestines and is specialised in its function so that it can selectively let the nutrients we need through the surface of our intestines and into the body while keeping our gut microbiota, food antigens (substances our body would have an immune reaction to), pathogens and toxins out.  

The intestinal epithelial barrier is a single layer of tissue cells controlling what gets let through into the body. This barrier has tight junctions which are very small gaps between cells, linked together by tight junction proteins. When these junctions are working well, only the nutrients, water, and electrolytes beneficial for our body are let through.  

Because of the impact compromised gut barrier integrity can have when unwanted substances get entry to the rest of our body the regulation of the intestinal barrier is very important. There are many different components of the gut barrier that work together to maintain barrier integrity and keep unwanted substances out of our body. These include the intestinal epithelial barrier, our gut microbiota, antimicrobial molecules, mucins (these make a mucus layer on the intestinal epithelial barrier which works to keep unwanted substances away from the barrier itself), and immune system components like immunoglobulins and cytokines. When the integrity of our gut is damaged and increased intestinal permeability occurs, the function of these components can change and the tight junctions increase in size. These bigger gaps mean other substances can more freely pass into and circulate around the body. When something changes to influence the way these different components operate, intestinal permeability can increase and this is when “leaky gut” occurs (1, 4). 

What happens when you have a leaky gut? 

When we have leaky gut, external substances, microorganisms, toxins and antigens, from our gut can gain entry to our bodies through the tight junctions in our gut barrier which have increased in size. These substances can make it into the blood or lymphatic system and circulate around the body. This can result in an immune response both locally, at the gut, or systemically, around the rest of the body. This trigger of the immune system can influence the development or severity of many diseases associated with a disrupted microbiome and leaky gut.  

These can include chronic inflammatory conditions and autoimmune diseases like rheumatoid and other autoimmune arthritis, inflammatory bowel disease, type 1 diabetes, coeliac disease, neurodegenerative diseases like Alzheimer’s disease, and some cancers. With research also showing it can be a factor in many health conditions including irritable bowel syndrome, obesity, type 2 diabetes, chronic fatigue, and neuropsychiatric disorders (1,2).  

Autoimmune disease and Leaky gut 

When unwanted substances, food antigens, microbes or toxins pass into the body because of a leaky gut, the immune system can be stimulated, with an immune reaction designed to eliminate these unwanted substances. In autoimmune disease autoreactive immune cells can be generated which create autoantibodies that attack our own body tissues, contributing to chronic inflammation and autoimmune disease (5). 

More recently, research has begun to find the impact gut health can have on autoimmune disease and development of other health conditions. Our gut microbiome composition can affect the immune system and proper functioning of the gut barrier, with evidence showing a relationship between gut barrier dysfunction and microbial translocation (where microbes gain access to the rest of the body via leaky gut), contributing to the development of these diseases (1, 5).   

Factors influencing intestinal permeability  

There are many different factors that can influence our gut microbiome, overall gut health, gut barrier function and increase intestinal permeability. The food and drinks we consume have a big impact on this a well as some medications, environmental toxins, and lifestyle factors like stress and exercise (1,2,4). 

Factors that can negatively affect intestinal permeability include:  

Alcohol: The more alcohol consumed, the greater the negative impact on the gut microbiome and intestinal permeability. 

Consuming a low fibre diet 

A high fat diet and high saturated fat intake 

A standard western style diet with low fibre, fruit and vegetables, and high in processed foods and sugar. 

Gluten: more specifically gliadin the protein found in wheat and gluten containing foods  

Highly processed foods and food additives: high salt intake, sugar, emulsifiers, surfactants, and organic solvents  

Infections: e.g. bacterial and viral 

Factors that can have a positive effect on intestinal permeability include: 

Consuming a high fibre diet with a range of plant foods: Short chain fatty acids are produced by our gut bacteria from fermenting fibre rich foods. Butyrate, acetate and propionate have been shown to support the health of our intestinal barrier. 

A Mediterranean style diet: Provides high fibre, anti-inflammatory foods, beneficial antioxidants and polyphenols and minimal processed foods. All of which help to support gut health. 

Vitamin D: get it from the sun or fatty fish, eggs, meat, dairy products and mushrooms if they have been exposed to UV light. 

Certain amino acids like glutamine and tryptophan:  

• Glutamine is the main source of amino acids making up the gut barrier. Glutamine rich foods include animal protein, meat, seafood, eggs, dairy and plant sources include legumes, nuts and seeds like almonds, peanuts and sunflower seeds, wholegrains like oats and rice, spinach, cabbage and soy products. 

• Tryptophan is metabolised by gut bacteria which produce substances to support gut barrier health. Tryptophan rich foods include animal protein like chicken, beef, fish, eggs, cheese, and plant foods like pumpkin seeds, lentils, chickpeas, quinoa soy products, almonds, walnuts and cashews.  

Retinol: the active form of vitamin A. Animal sources provide retinol, found in eggs, oily fish, dairy products and liver. Plant sources of vitamin A can be converted to retinol, sources include lots of orange foods, carrots, sweet potatoes, pumpkin, and dark green leafy vegetables. 

Polyphenols: These are plant compounds with beneficial effects for humans. Some of these specifically found to have benefits on gut health include quercetin, found in many foods including onions, capsicum, asparagus, apples, and broccoli. Myricetin, found in blueberries, tea, oranges and tomatoes. Kaempferol found in broccoli, spinach, kale and tea. Curcumin, found in its highest quantities in turmeric. 

Zinc can help reduce intestinal damage, support healthy cells of the gut barrier and help reduce inflammation. Food sources include oysters, red meat, pumpkin seeds, legumes, oats, cheese, peanuts and eggs. 

Probiotics can promote the balance of good microbes in our gut to support our gut health. You can find them in foods like yoghurt, kimchi, sauerkraut, and kefir.  

Prebiotic rich foods provide food for our beneficial gut bacteria and support gut health. These include onions, garlic, asparagus, artichoke, flax seeds, apples and many fibre rich foods.  

Overall

Eating a well-balanced diet with lots of variety, plants foods, fibre, and minimal intake of processed foods, alcohol and sugar, help to support good gut health and well-functioning intestinal permeability. With specific nutrients and foods that can provide added benefits.  

For people with autoimmune disease, chronic inflammation, struggles with gut health and other health conditions with a gut health and increased intestinal permeability component, it can require a more specific individualised approach. In these instances, there can be many contributors impacting the functioning of our gut and immune system, with the potential for food sensitives to have developed as well as lifestyle factors like stress, exercise, sleep and environmental factors all possibly contributing to overall wellbeing and gut health. 

If you want to improve your gut health, have been struggling with inflammation, autoimmune challenges, ongoing fatigue or symptoms that are stopping you from feeling your best. Lets chat! Book a free 15-minute online wellness investigation with me, we can get started on finding the root cause and creating a personalized plan to help you feel better, reduce symptoms, and reclaim your health. 

References

1. Leaky gut as a danger signal for autoimmune disease 2017. DOI: 10.3389/fimmu.2017.00598

2. Diet, microbiota, and gut permeability – the unknown triad in rheumatoid arthritis 2018. DOI: 10.3389/fmed.2018.00349

3. The influence of nutrition on intestinal permeability and the microbiome in health and disease 2022. DOI: 10.3389/fnut.2022.718710

4. Nutritional keys for intestinal barrier modulation 2015. DOI: 10.3389/fimmu.2015.00612

5. Gut microbiota, leaky gut and autoimmune disease 2022. DOI: 10.3389/fimmu.2022.946248