Written by Dana Trentini, May 26, 2020

Gut, Brain, Skin, They Are All Connected

In 1930, dermatologists John H. Stokes and Donald M. Pillsbury first proposed the gut-brain-skin theory. They hypothesized that emotional stress (like worry, nervousness, depression or anxiety) could disturb the normal gut microbiota, increase intestinal permeability, and contribute to local and systemic inflammation that often manifests in the skin.[1]

The Gut-Brain-Skin Axis

This concept of a gut-brain-skin axis has been whirring in my mind for years ever since reading about this genius theory that lay dormant for decades in the scientific literature.

When client after client with a whole host of skin conditions, from acne to eczema to rosacea to hives, as their main health complaint inevitably go on to tell me about their years of digestive upset and mood imbalance, it is not shocking really, not anymore, not since I learned about the gut-brain-skin axis. 

I have yet to see someone with a skin issue without an accompanying gut imbalance. And here’s the thing. Oftentimes people with gut dysfunction have no expected gut symptoms. There can be zero digestive symptoms yet lab markers tell a completely different story. And by gut dysfunction I mean a myriad of underlying dysfunctions including low stomach acid, low “healthy” gut flora, opportunistic pathogens, small intestinal bacterial overgrowth (SIBO), leaky gut, blunted villi. Skin conditions abound including acne vulgaris, rosacea, dermatitis, psoriasis, eczema, hives, and let’s not forget the skin on our scalps including dandruff and hair loss.

And let’s not forget the power of stress, including emotional stress, to throw our bodies completely off kilter. If you’ve ever developed sudden symptoms after a major stressful event like the loss of a loved one, divorce, job loss, or major surgery, you know what I’m talking about.

Gut, Brain, Skin, They Are All Connected

The Gut-Brain Axis

There is growing scientific evidence that the gut and brain communicate with one another in a bidirectional manner through what’s known as the gut-brain axis. And that our gut microbiota play a critical role in that communication. 

Researchers in this study included a long list of the studies providing evidence of the modulatory role of the microbiota in brain-related pathological conditions including anxiety, depression, mood, and decreased cognitive function.[2]

More than 90% of the body’s “happy” neurotransmitter serotonin is produced in the gut. New research illuminates the critical role of the gut microbiota as a regulator of serotonin synthesis.[3]

The gut is an incredible piece of art. Not surprisingly, it is often referred to as the “second brain”.

Probiotics, Prebiotics, Omega 3

Way back in 1930, Stokes and Pillsbury even proposed the use of probiotic Lactobacillus acidophilus cultures (we now know probiotics are helpful in restoring healthy gut flora) and cod liver oil (we now know omega 3 fatty acids are anti-inflammatory) light-years ahead of their time.[4] 

Eating live microorganisms? Remember our gut is home to trillions of beneficial microbes that help keep our bodies in tip-top condition. It’s about boosting the microorganisms that are “good” for you to help act as a competitive barrier against the unwanted pathogenic “bad” ones. 

And then there are the powerful diagnostic tests that have exploded on the scene over the last decade that analyze the vast army of “beneficial” and “harmful” microbes living in our guts and that has elevated our ability to optimize health by leaps and bounds.

These two pioneering researchers also cited research that as many as 40% of people with acne have hypochlorhydria, that’s low stomach acid, and that low stomach acid sets the stage for microorganisms that normally live in the large intestine to migrate up to the small intestine where they shouldn’t be. Today we refer to this condition as SIBO (small intestinal bacterial overgrowth).[5]

Today’s researchers have finally turned their attention to probiotics, prebiotics, and omega 3 fatty acids in fish oil for skin disorder management.[6,7]

Your Skin Is The Window To Your Gut

The gut and skin connection has been extensively studied. In a population-based cohort study of almost 50,000 Danish patients with rosacea, for example, prevalence of the GI diseases celiac disease, Crohn’s disease, ulcerative colitis, Helicobacter pylori (H Pylori) infection, small intestinal bacterial overgrowth (SIBO), and irritable bowel syndrome was higher.[8] 

One study of over 13,000 adolescents found gastrointestinal dysfunction (halitosis, gastric reflux, abdominal bloating, constipation) a significant risk factors for sebaceous gland diseases, namely seborrhea, acne, adrogenetic alopecia, and rosacea.[9] Seborrhea is a common skin problem that presents with itchy rash and white scales. When it affects the scalp, it is called dandruff or cradle cap in infants.

A study was conducted in China of children under 6 months of age suffering from eczema. High levels of opportunistic pathogens were detected in their stool samples such as Klebsiella, Salmonella, and Shigella.[10]

New Fields of Medicine

And here’s a big move forward. The relationship between chronic skin conditions and mental health is becoming more widely accepted, and burgeoning fields of psychodermatology and neurodermatology in medicine have even emerged. 

In my crystal ball, I see a future where the silos of medicine are broken down and interdisciplinary fields of all kinds develop. Thinking about the gut-brain-skin condition, I wouldn’t be surprised if a day comes when a field that combines gastroenterology, dermatology, and psychiatry emerges but hey this is a great start. 

I wonder if those dermatologists John H. Stokes and Donald M. Pillsbury ever thought this day would come. 90 years later and it is about time.


[1] Stokes JH, Pillsbury DH. The effect on the skin of emotional and nervous states: theoretical and practical consideration of a gastrointestinal mechanism. Arch Dermatol Syphilol. 1930;22:962–93.

[2] Mohajeri, M.H., et al. Relationship between the gut microbiome and brain function. Nutrition Reviews. Jul 2018;76(7):481-496.

[3] Yano, J.M., et al. Indigenous bacteria from the gut microbiota regulate host serotonin biosynthesis. Cell. 9 Apr 2015;161(2):264-276.

[4] Bowe, W.P., Logan, A.C. Acne vulgaris, probiotics and the gut-brain-skin-axis – back to the future? Gut Pathogens. 2011;3:1.

[5] Bowe, W.P., Logan, A.C., Patel, N.B. Acne vulgaris, probiotics and the gut-brain-skin axis: from anecdote to translational medicine. Beneficial Microbes. 2014;5(2):185-199.

[6] Szántó, M., et al. Targeting the gut-skin axis – Probiotics as new tools for skin disorder management? Experimental Dermatology. Nov 2019;28(11):1210-1218.

[7] Huang, T., et al. Cosmetic and Therapeutic Applications of Fish Oil’s Fatty Acids on the Skin. Marine Drugs. Aug 2018;16(8):256.

[8] Egeberg, A., et al. Rosacea and Gastrointestinal Disorders: A Population-Based Cohort Study. Br J Dermatol. 2017 Jan;176(1):100-106.

[9] Zhang, H., et al. Risk factors for sebaceous gland diseases and their relationship to gastrointestinal dysfunction in Han adolescents. The Journal of Dermatology. 2008; Oct 2008;35(9):555-61.

[10] Wang, H., et al. Dysfunctional gut microbiota and relative co-abundance network in infantile eczema. Gut Pathogens. 2016;8:36.

Gut, Brain, Skin, All Connected

Dana Trentini

Dana Trentini

One day my body suddenly broke from hypothyroidism. I clawed my way back to health by devouring the scientific literature. You see, I was once the team leader of an Ivy League professor’s research team with no clue then that those skills would one day save my life and that my site Hypothyroid Mom would spread across the internet like lightening. And then came the day to share all my other precious health nuggets and Yes! Healthier was born.

Please help spread the word (I appreciate every share!)

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