How Does the Gut-Skin Axis Impact Skin Disorders?
When things go awry with our skin it can be the source of substantial physiological and psychological torment. The skin serves as the barrier between the external world and our precious organs and systems inside our body. It is also the organ that makes up the majority of our appearance, to which we apply beauty products, adorn with jewelry, and tan in the sun. It is the material with which we face the world. It is also a critical factor in how the rest of the world views us, and thus skin diseases pose a unique challenge as not only do they create a disturbance in our first line of immune defense, but there is often a reduced quality of life that comes with physical alteration. Redness, swelling, rashes, and pus are not only painful, itchy, and uncomfortable for us, but they makes us feel self-conscious and sometimes prompt us to withdraw from engaging with our community.
In the Global Burden of Disease report from 2013, skin and subcutaneous disorders ranked globally as the 18th leading cause of disability-adjusted life years. Not to mention the financial burden that costs hundreds of millions of US dollars per year. With all this money spent, why is this still such a pervasive problem?
Recent research has begun to reveal exciting connections that are already changing the way practitioners view and address disorders of the skin.
While there have been associations made between the skin and the microbiome in the gut, studies are now finding a strong causal link between the two.
What does this mean and why does it matter?
This means that it isn’t just similar populations that have both skin diseases and gut diseases due to common lifestyle factors, but that there is a direct relationship between the two. This matters because with our existing technology and the tests available, we are able to determine what is disturbed in an individual’s gut microbiome and formulate treatment protocols that are tailored to that specific person’s profile.
Many of the common treatments used by dermatologists today do not address the gut microbiome and often have unwanted side effects that can persist for the duration of the patient’s treatment, or even their lifetime.
We’ve previously explored the connection between the brain and the gut, so in this article let’s take a look at what’s really going on with the gut and the skin. We will find out what the gut-skin-axis actually is, what makes a healthy gut or an unhealthy gut, what factors influence the axis, and how we can use this knowledge to address many skin diseases once and for all.
What Exactly Is the Gut-Skin Axis?
The connection between the skin and the gut has finally been determined to be bidirectional and causal, which means that they both influence each other directly. It isn’t necessary to be literate in scientific jargon to understand what is happening, but we’ll review some of the functions of each system in case anyone forgot from high school biology class, and then it will make a lot more sense when we look at the way it is all interrelated.
The skin covers 2 square meters and is the largest organ in an adult’s body.
Its main roles are as both an immune and a physical barrier which protects us against external pathogens and act in both innate and adaptive functions. The gut microbiome has trillions of microorganisms and has its own protective barrier lining the gut that addresses what comes into the gastrointestinal tract, as well as what comes through internal pathways through the blood and endocrine system. It influences our immunity in this way, as well as our metabolism and hormone regulation.
When we are born, the quantity and diversity of our gut microbiota rapidly increases for the first three years of life before leveling out for most of our youth and adulthood and then declining in our aging years. We gain our initial microbial community from the birth canal and through breast milk (which contains high levels of fatty acids and oligosaccharides), and then later through our external environment. In addition to the gut, there is a different profile of microbial species in the areas of the vagina, oral tissue, airways, and the skin. Within the skin, different sites also differ in composition of bacteria such as the forearm, the forehead, and the sternum.
When the gut is impaired, or the balance of good bacteria to ‘bad’ bacteria is disturbed (called ‘dysbiosis’), then there is increased permeability in the lining. When this occurs, the proinflammatory molecules and metabolites can leave the gut and travel through the bloodstream directly to the skin where they accumulate.
Over time this leads to conditions such as acne, psoriasis, rosacea, dermatitis and photoaging, often accompanied by gut symptoms such as those seen in Irritable Bowel Syndrome (IBS) and Inflammatory Bowel Disease (IBD). In fact, when the gut of those with some of these skin diseases is investigated, they will have a different microbiome profile compared to those without skin diseases, even in lieu of obvious gastrointestinal symptoms.
While the effects of the gut on the skin can cause unsightly rashes, it is important also to appreciate the impact that is occurring on the immune system of the host. There is a range of complex activities taking place involving T cells, B cells, Mast cells, macrophages and inflammatory mediators as well as lipids, nucleic acids, liproproteins and proteins. The gut works hard to take indigestible polysaccharides and convert them into vitamin K, and B12 primarily, as well as Short Chain Fatty Acids (SCFAS), such as poprionate and butyrate. These are critical in maintaining and repairing the integrity of the gut lining and the functioning of the innate and adaptive immune systems, and the balance of bacteria in both the gut and the skin.
It can get complicated to go deep into the specific compounds and processes, but the main idea is quite simple. Both the skin and gut are critical in the regulation of the immune system, metabolism, and endocrine system, and they communicate directly in order to manage these systems. This direct communication means that when things are disturbed on one end, it can manifest with symptoms and signs on the other end.
What happens in the gut, also happens in the skin.
What Does a Healthy Gut Look Like?
So, we’ve talked about pathogens and inflammation, gut permeability and the resulting skin diseases.
What is the gut actually supposed to look like?
The gut in this context really means the entire gastrointestinal tract (GIT) which begins in the mouth and finishes in the anus, including the stomach and intestines along the way. In order for the GIT to function normally, including its co-regulation of the immune system with the skin, it needs to be free of inflammation and have the appropriate balance of beneficial bacteria and detrimental bacteria. Inflammation and dysbiosis are what lead to impaired permeability resulting in the metabolites and inflammatory cells reaching the skin. So what leads to alterations in the GIT in the first place?
What Factors Influence the Gut-Skin Axis
Early Life
We have already touched on the microbiota at birth but it is worth revisiting for a moment. The early years have a great impact on our personal gut microbiome development and imbalances can affect us well into our adult years if left unaddressed. We gain the majority of our beneficial bacteria from the birth canal during vaginal delivery, and in breast milk during our first feeds.
You can imagine that babies who are born through Cesarean section or are formula fed will have a much different balance of bacteria as a result. Formula fed babies have been found to host more inflammatory species while breastfed babies benefit greatly from the high levels of beneficial bacterial diversity.
Adult Environmental Factors
While we have little control over what happened to us at birth and during infancy, our lifestyles and external environment can play either a healing or harmful role in managing our microbiome. These are some of the main factors contributing to dysbiosis and altered gut bacteria (and resulting manifestations in the skin):
Types of fat in the diet: Refined hydrogenated oils and industrial trans-fatty acids increase the number of harmful bacteria and lead to inflammation and delayed skin wound healing. These include sunflower, safflower, soybean, corn, canola and vegetable oils.
Fiber: Fiber is not digested like the rest of food items but rather metabolized and converted into fatty acids which contributes to anti inflammatory effects. Low fiber diets can be problematic for this reason.
Antibiotics: These are well known for their role in killing harmful bacteria, but also beneficial bacteria and inhibiting the growth of entire microbial groups. This throws off our bacterial balance and leads to problems in the skin such as Candida and faster aging.
Western diet: Much of the common diet eaten in the West has been shown to increase insulin-like growth factor and insulin which influence the gut microbiota. This can lead to dysbiosis.
What Are the Treatment Options
So, what do we do now that we know we probably have some inflammation and bacterial imbalance occurring in our gut, leading to our skin diseases? T
he good news is that there is technology and testing available already which is used to look at the components of our stool, our intestinal lining, and inflammatory markers. While research is beginning to determine which bacteria seem to be most beneficial for specific conditions, it needn’t be a guessing game of trying out every diet and probiotic on the market, or diving into toxins and parasite cleanses we see advertised on social media. It’s really important to determine the state of your individual bacteria to find out which strains are in excess or deficiency before treating them blindly. This is where working with a functional medicine doctor becomes key.
There is a lot of talk on probiotics and prebiotics for gut health in general.
So far the researchers seem to agree that both of these provide some benefits to the skin, although the mechanisms of action are still not completely known. Probiotics provide benefits by increasing the number of beneficial microbes and contributing to diversity which may affect the skin barrier function and its physical presentation. Probiotics may help prevent unhealthy bacteria from colonizing the gut and encouraging anti-inflammatory responses. That said, it’s still important to access appropriate testing before adding these in as some conditions are aggravated by probiotics if they aren’t treated first.
Working one on one with a practitioner will allow you to have individual testing to address what’s truly going on inside so you don’t have to rely on skincare reviews from the internet or medications that provide temporary symptomatic relief while often causing long term adverse effects.
A functional medicine practitioner can offer these tests as well as a personalized protocol to help you find the right diet (that you actually like!) and appropriate additional supplementation to help your skin heal from the inside and in turn, improve the health of your entire body.
In addition to healing your skin, you can improve digestive symptoms, reduce the discomfort of skin disease manifestations, and feel comfortable engaging with the world again.
Dr. Jenny Bisset
Founder of The Bisset Method
JB Wellness
Chinese + Functional Medicine
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