The digestive tract (a.k.a. the gut) is a complex system that absorbs nutrients and gets rid of waste, and our overall health is affected by its function. We know how important it is to get all of our essential nutrients from food, and this is a big part of what our digestive tract does. But, there is way more to the story than just that.
When the gut is not working properly, symptoms can appear. Yes, typical gut and abdominal symptoms, but also other seemingly unrelated symptoms. Did you know that things like allergies, autoimmunity, and mental health have been linked with gut problems?
Let’s look at one gut problem in particular, and you may have heard about this lately. Leaky gut. This literally involves tiny “leaks” in our gut lining that can allow more than just needed nutrients and water into our bodies. Researchers are looking at this, and opinions vary, but I want to share the latest with you. I also want to give you some helpful strategies to optimize your gut health and overall health.
The gut, part of the digestive system (mainly the intestines), is an alive and very complex “tube” that acts as a gateway deciding what will enter the internal circulation of the body, and what must not get through. It digests and absorbs nutrients and water, and prevents toxins and “bad” microbes from being absorbed. It also transports all the waste onward to be eliminated.
You may think that symptoms of a leaky gut (a.k.a. “intestinal permeability”) are felt in the gut, and you’re right, but only to a point. Many are surprised to learn that several symptoms and health conditions are linked with poor gut health.
Some diseases associated with leaky gut include autoimmune diseases (e.g. Type I diabetes, celiac disease, etc.), Inflammatory Bowel Diseases (e.g. ulcerative colitis, Crohn’s), psychological stress, and mental health.
Researchers are still figuring out the exact role that leaky gut plays in these conditions. Either way, there is a link, and there are things that you can definitely do to improve your gut health. But first, I think it’s important to look at how the digestive tract is structured, and what can promote it to leak in the first place.
Gut structure – three layers of our gut lining
Our guts have a three-layer lining that helps to allow things we need in, and keep harmful things out. The first (outermost) layer is a barrier that absorbs the nutrients and water we need, and physically prevents undigested compounds, toxins, and bacteria from getting in. This barrier is the area between the internal circulation of our bodies and the outside world (what we eat and drink) and 90% of it’s cells are called “enterocytes.” These enterocytes actively absorb what we need and keep out what we don’t. They also help to create and regulate the other two layers.
Enterocytes are held together with different types of bonds. The one most studied is called a “tight junction.” These tight junctions are made up of several types of protein. When they loosen, it creates tiny holes (or permeations) in this first layer since the cells are not as “tight” as they should be.
The second layer is mucus. This mucus provides physical separation between the outermost layer and the microbes, and food that is inside the centre of the gut. It also contains special proteins that help fight against invaders. This mucus and its special compounds are produced by the enterocytes.
A thick mucus layer provides a better barrier between the one-cell layer of enterocytes and protects them from “bad” bacteria that can enter. Interestingly, animal studies show that mice fed a diet low in fibre had thinner mucus barriers.
The third (innermost) layer is our friendly resident gut microbes. Our guts contain billions of microbes and together, they’re sometimes referred to as a “superorganism.” This layer of gut microbiota has two major functions to help promote a healthy gut lining:
● They crowd out “bad” bacteria by taking up space and eating the “good” food (i.e. fibre and resistant starch, which we’ll get into in a bit).
● They help to regulate the digestion and absorption of nutrients to nourish the first-layer enterocytes. One of the types of compounds they produce are called “short chain fatty acids” (SCFAs). These are considered to be anti-inflammatory and are also used as fuel for the enterocytes.
This is a very condensed version of how gut health affects our overall health, however, when the three layers aren’t working optimally, the tight junctions loosen, leaks occur, allowing undesirable “things” to enter into the body’s circulation.
Leaky gut and our gut microbes
Our friendly gut microbes (the third innermost layer of our gut) include hundreds of types of microbes, and studies suggest that problems with our gut microbes might actually begin the whole process of leaking guts. Based on current research, it is believed that this happens when:
● The third innermost layer of the gut lining, the microbiota, gets out of balance.
● Inflammatory molecules (including zonulin, which we will discuss later) are released, and fewer anti-inflammatory ones like SCFAs are available.
● This inflammation disturbs the tight junctions in first layer of enterocytes, thereby creating tiny leaks, which allow passage of harmful compounds into our bodies.
It starts when there is an “imbalance” of “good” and “bad” gut microbiota, often referred to as dysbiosis. This promotes an inflammatory response because some of the “bad” microbes are pushing out the “good” ones that produce the anti-inflammatory short chain fatty acids. Some of these SCFAs promote the production of the mucus layer (the second layer), and even help to improve the tight junctions in the enterocytes in the first layer.
Another possibility that researchers are looking at is that some of these “bad” bacteria produce a toxin that mimics the protein zonulin. Zonulin is naturally released by our enterocytes when they’re exposed to certain things we eat, like “bad” bacteria on our food, and gliadin (part of the gluten protein found in wheat and other grains).
Interestingly, blood levels of zonulin tend to be higher in people with autoimmune conditions like celiac disease and type 1 diabetes.
All of this increased inflammation then irritates the gut, which can result in loosening of those tight junctions. Based on the research so far, this is the way we think we develop leaky guts. But, how does this relate to autoimmunity?
Leaky gut, allergies, and autoimmunity
Allergies and autoimmunity are directly linked to our immune system and they result when our immune system works a bit too hard; when our immune cells become a little too active.
Allergies occur when our immune system is activated to fight things that are not harmful, like certain foods, pollen, or pet dander. The body thinks they’re dangerous invaders that must be fought, and sends out immune cells that cause inflammation to try and eliminate the allergen.
Autoimmunity, on the other hand, is when our immune system is activated to fight our own cells and tissues. The immune system becomes “intolerant to self.” For example, type 1 diabetes (an autoimmune disease) occurs when our immune system fights the insulin-producing cells in our pancreas. After continued inflammation, enough of these cells die and we eventually need to start monitoring our own blood sugar levels and provide our bodies with external insulin.
Many things can contribute to autoimmunity, and leaky gut may be a bigger factor than we once thought. This is because of the impact of allowing undigested food, bacteria, etc. to enter our bodies and how our immune system tries to fight them. A large part of our immune system is located just on the other side of that first layer of enterocytes.
When our bodies detect things in our internal circulation that don’t belong, our immune system kicks in. This immune response to things that “leaked” into our bodies can cause the release of even more inflammatory compounds, this time inside our bodies and bloodstreams (i.e. on the other side of the first layer of enterocytes). The allergic and inflammatory responses that happen around our guts may affect the gut directly, and once these are absorbed into the bloodstream, they can affect other parts of the body as well.
This is the connection we see between leaky gut, allergies, and autoimmunity. It’s not just the leaky gut, it’s the interactions between what leaks into our bodies and our immune system’s response to them.
Having a healthy gut microbiota plays an important role in how our immune systems mature from when we were infants. Dysbiosis in our gut at an early age can promote changes in our immune response, and increase the risk of developing allergic and autoimmune diseases, as children, and later in life.
It seems that gut dysbiosis and “leaky gut” might be part of the chain of reactions that lead our immune cells to start attacking things they really don’t need to.
Leaky gut and mental health
Stress hormones and moods can result in reduced levels of mood-boosting neurotransmitters in the brain and increase the risk of developing gut disorders, or flare-ups of existing gut disorders. Several studies have found that patients with inflammatory gut conditions experienced worsening symptoms after stressful events. Chronic, or long-term stress and depression are associated with more gut pain, leaky gut, and other inflammatory conditions such as Crohn’s and ulcerative colitis. Stress can affect changes in the microbiota and the lining of the gut, and can further increase the gut inflammation. In animals, studies show that being under stress increases their intestinal permeability and inflammation.
It was once thought that the brain sent direction down to control all parts of our bodies, but we are learning that a lot of the communication between the gut and the brain actually starts in the gut and goes up to the brain. Research shows that in about half of people studied, gut symptoms arose before the mood issues did.
People who have gut disorders have a higher risk of developing anxiety or depression. Sometimes experiencing symptoms like abdominal pain, bloating, and discomfort can affect the quality of life and moods of people who have inflammatory bowel disease.
These links between the gut and mental health are because of the “microbiota-gut-brain axis.” This axis includes many connections between the two, including nerves and hormones.
When the areas of the brain associated with stress are activated, it initiates the stress response. First, it includes the release of stress hormones that go through the whole body. Second, it includes activation of the “fight or flight” (autonomic) part of the body’s nervous system. Both the hormones and autonomic nervous system affect the gut. And these can affect all three layers of the gut lining.
Cortisol, one of the key stress hormones from the adrenal glands, is released into the bloodstream when we’re under stress. Cortisol directly affects the gut by reducing our ability to properly digest food, and instead goes into survival mode. It essentially prepares for “fight or flight” by slowing down digestive functions.
All this being said, what can we do about leaky gut?
When our “good” gut microbes are happy eating their favourite foods they have positive effects on our gut - crowding out the “bad” microbes and producing beneficial anti-inflammatory compounds like SCFAs. An important fact to consider is that the type of microbes that live in our gut is established by the time we’re 3-5 years old, and about 30-40% of it can be influenced by factors such as diet.
According a recent study by Aguayo-Patron, who looked at “Old Fashioned vs. Ultra-Processed-Based Current Diets” and the “possible the implication in the increased susceptibility to type 1 diabetes and celiac disease in childhood”, “Diet is the main factor that influences gut microbiota composition.”
1 - Eat more fresh, unprocessed, and minimally processed foods such as quality fruits, vegetables, nuts, seeds, and fish.
These foods contain higher amounts of fibre and “resistant” starch. Sugars and easily digested starches are broken down and absorbed into the bloodstream as sugar. Resistant starches and fibre, on the other hand, are “resistant” to this process and make it all the way through our intestines to where most of our gut microbes live. These can then become food for our “good” gut microbes and promote their health. Another way whole and minimally processed foods help our gut microbes is because they contain lower amounts of trans and saturated fats, and higher amounts of healthy fats.
2 - Ditch the ultra-processed and fast foods:
These foods lack nutrients and tend to be high in calories, fat, sugar, salt, and additives. Foods that have a lot of sugar are easily digested and result in raised blood sugar. These foods also contain very little fibre and resistant starches, have more total fat (including trans and saturated fats), are not very filling, and promote obesity. They also promote inflammation and gut dysbiosis, both of which are factors associated with intestinal imbalance.
3 - Pay attention to potential food intolerances
Some gut symptoms may be related to food intolerances. Certain people may have undiagnosed celiac disease, or be sensitive to proteins in gluten and can benefit from removing it from the diet. There are a lot of gluten-free foods available now, however ultra-processed gluten-free foods are still ultra-processed and should be avoided in favour of fresh and unprocessed foods.
Also, some people are intolerant to certain carbohydrates called FODMAPS (fermentable oligo-, di-, and mono-saccharides and polyols). These are found in stone fruits, some vegetables, legumes, lactose-containing foods, and artificial sweeteners.
4 - Reduce alcohol
Alcohol can stress our friendly gut microbes and can disrupt the function of our three-layered gut lining. It can cause bacterial overgrowth, and at the same time reduce some of the “good” microbes. Additionally, it’s important to know that some “bad” bacteria, including E. coli can produce alcohol, so this may be one of the ways that they contribute to leaky gut.
5 - Consider probiotics
Probiotics are live microorganisms that have a beneficial effect on human health. They are found in fermented foods like kefir, kombucha, miso, kimchi, and fermented vegetables. They are also available as dietary supplements. Yogurt is also fermented, however commercial yogurts are processed and contain very little benefit, Additionally, they are often high in sugar, additives, and other non-gut-friendly foods. Making your own yogurt, kombucha, kimchi and kefir is very easy to do. Here is a link to making yogurt…http://pecanbread.com/f/tanya/yogurthowto.html.
Infections and use of antibiotics, especially during the first months of life, can have a negative effect on our gut microbiota. If you have to take an antibiotic, ask your healthcare professional if you should also take certain probiotics to help reduce the impact on your gut microbiota.
Clinical trials are being done to test whether probiotics may benefit inflammatory gut conditions even without antibiotic use. More research is needed to confirm which amounts of which types of probiotics are the most beneficial for which conditions.
In conclusion, leaky gut, or “intestinal permeability” is linked with many conditions of the gut, the body, and the mind. While research is still figuring out exactly how this happens and what comes first, there are definitely steps you can take today to help optimize your health.
People who eat a healthy, whole foods diet tend to have happier gut microbiota, less inflammation, and a nice strong non-leaky gut lining. If you are considering the addition of supplements to support your gut health, be sure to consult with a knowledgeable healthcare professional.
This is Janice, inspiring change