Skin troubles may be a sign of what’s going on in the gut.
What protects your body from the outside world? You probably first think of your skin. Your skin is an incredible organ (yes, it is an organ!) that keeps your insides in and the outside out. It is large, too; the average person has 1.5-2 square meters of skin. But the skin is just the beginning of our barrier to the outside world. Our gut lining does the same thing, helping us let in the nutrients we need and keep out what we don’t – and its surface is 15-20 times larger than the surface of our skin!
Both of these barriers are covered with their own microbiota – communities of bacteria and other microorganisms that, when healthy, perform important metabolic functions that are vital to our wellbeing. (The term “microbiome” refers to the combined metabolic activity of the microbiota.) Yes, bacteria on our skin are a good thing! Just like in the gut, friendly (also called “commensal”) microbes on the skin help keep away infectious ones and balance our immune responses. These two barriers have a lot more in common, too. The one we can see, our skin, might be a window into the one we can’t – our gut.
In the 1930’s, dermatologists John Stokes and Donald Pillsbury proposed a relationship between skin conditions, mental health, and the gut. (Maybe you’ve heard of the gut-brain axis? More like a gut-brain-skin triangle!) They hypothesized that depression and anxiety alter gut function, causing changes to the normal microbiome, which in turn cause inflammation that can manifest on the skin as acne, dermatitis, rosacea, and more. This may be a vicious cycle – as anybody who’s had blemished skin will attest, it can certainly affect self-esteem. Ninety years later, research is just starting to catch up. We now know that anxiety and depression can alter the gut microbiome, leading to inflammation, and that a dysfunctional gut microbiome may alter brain function, leading to anxiety and depression. The microbiome is emerging as a central piece to the puzzle. Let’s take a look at how gut health may play a role in acne and rosacea.
One bacteria species is typically vilified as the cause of acne – Cutibacterium acnes (formerly Proprionibacterium acnes). (They even named it after the disease!) However, we now know that C. acnes is typically a commensal species, and is equally abundant in the sebaceous oil glands of those with acne and those without. So what might cause them to flip?
Several studies have shown that blood samples from people with acne readily form microclots and activate the pro-inflammatory complement cascade upon exposure to lipopolysaccharides (LPS, fragments of Gram negative bacteria cell walls) and normal colonic bacteria, while those without acne do not. This suggests that individuals with acne have greater exposure to LPS and colonic bacteria in circulation, pointing to compromised intestinal permeability, often called “leaky gut.” High levels of certain types of LPS in the blood – also called metabolic endotoxemia – can independently drive up blood sugar levels, and has been implicated in systemic diseases from fatty liver to diabetes.
Other studies have found that people with acne have altered colonic microbiota. Researchers have found lower levels of healthy microbes like Lactobacillus, Bifidobacterium, Butyricicoccus, and Allobaculum. These microbes support a healthy gut barrier, reduce inflammation, and regulate metabolism, in part through the production of short chain fatty acids like butyrate. You can test for levels of these organisms and metabolites with a functional medicine physician, by doing a comprehensive stool test. Populations of certain bacteria can be altered by using prebiotics, probiotics and antimicrobial herbs.
Inflammation is central to rosacea, and it might begin in the gut. Research has found strong associations between rosacea and inflammatory gut disorders including Crohn’s, ulcerative colitis, IBS, SIBO, and celiac disease.
While the colonic microbiome may be a driver of acne, the small bowel microbiome appears to be the more important factor in rosacea. We see that many people with SIBO (small intestinal bacterial overgrowth) find their rosacea clears after treatment. Research suggests SIBO may be up to 13 times more prevalent in people with rosacea. Common symptoms of SIBO include bloating, abdominal discomfort, gas, burping, diarrhea, or constipation. A functional medicine doctor can test you for SIBO to determine if your small intestinal microbiota may be contributing to rosacea.
Leaky gut may play a role in rosacea as well. A recent study found that serum zonulin, an indirect marker for increased intestinal permeability, is markedly elevated in people with rosacea.
Unlike in acne vulgaris, people with rosacea appear to have imbalanced skin microbiota. But it’s unclear whether these perturbations cause rosacea, or may themselves be caused by changes in the gut microbiome.
It’s unlikely that all acne and rosacea is caused by problems with the gut microbiome. But if you have skin troubles, in addition to working with a dermatologist or your primary care physician, it is important to investigate your gut health – with the help of a qualified functional medicine physician. Even in the absence of gastrointestinal symptoms, supporting the gut microbiome and the selective permeability of the intestinal wall may be the key to clear skin.
If you do have gastrointestinal dysfunction, healing your gut may heal your rosacea. A small study in individuals with SIBO and rosacea found that 69% reported notable improvement or complete clearing of rosacea after treatment with rifaximin (an antibiotic for SIBO). But for many, the answer is not straightforward. As a part of a comprehensive gut restoration protocol, a functional medicine doctor may use probiotics, which are supplemental beneficial live microbes. Several clinical trials have shown that oral probiotics can improve outcomes in acne treatment, likely by modulating inflammation via the microbiome.
A recent systematic review found that the consumption of foods that spike blood sugar is strongly correlated with acne, and many people find that cutting their sugar intake helps. The real reason why may be in the gut: high blood sugar can directly cause pathological intestinal permeability. Ditching sugar is an important first step, but alone it may not be enough – you may have to heal the gut too!
Topical probiotics, applied to the skin, may also be a useful strategy for both acne and rosacea. Many clinical trials have demonstrated their effectiveness , and topical probiotic products abound, though like oral probiotics their quality is variable. Many products have lower numbers of viable cells than they claim, or don’t even contain the strains on the label. Worse, many are contaminated with harmful strains, or contain un-tested strains with unknown effects. A functional medicine doctor can help you identify a topical probiotic that may be right for your skin.
There are no silver bullets for the microbiome. Balance is far more important than any single microbe or test result. But the benefits of optimizing the gut are vast, and extend far beyond the skin. As the father of western medicine, Hippocrates, said, “all disease begins in the gut” – which means it ends in the gut too! The Institute for Functional Medicine’s “5R” program is a powerful framework we use to establish healthy gut function: removing what is getting in the way, replacing missing enzymes and nutrients when indicated, reinoculating with the right probiotic microbes, repairing the gut lining, and rebalancing lifestyle to support ongoing health. With these tools, gut healing is possible for anyone – which may be what you need for healthier skin.
Written by Jonah Udall; reviewed and edited by Dr. Bojana Jankovic Weatherly. Jonah Udall is a nutritionist, herbalist, and functional medicine practitioner in-training, earning his Masters of Science in Human Nutrition and Functional Medicine at the University of Western States. Chronic health challenges taught him the importance of listening deeply, seeking the root causes of dysfunction, celebrating the individual, and finding collaborative paths to vibrant health with nature’s medicines. Jonah is also a professional musician and movement artist, director of New York City-based ECHOensemble, and a certified Deep Listening instructor.
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