The connection between gut health and all manner of other wellness interests has been the subject of study for decades. In the last fifteen years or so, commentary on thegut-brain axis has even brought to light theirrefutable relationship between compromised gut health and deficient mental well-being (see: excessive stress, anxiety, depression, and more).
An even more recent (and exciting!) development is scientific exploration of thegut-skin axis.
Ahead, we’ll explain the gut-skin axis, how one affects the other, immune risk factors, how gut health contributes to specific skin conditions, and solutions that may help to assuage disturbances in contentment of your bellyand skin.
What Is the Gut-Skin Axis?
The gut-skin axis refers to the tightly connected, cyclical relationship between the gut microbiome and skin health – between which the immune system acts as a mediator.
The associations between the gut and skin are so strong that research has specifically connected several inflammatory skin diseases with a compromised gut microbiome.One study suggests that gut imbalances are directly correlated to acne;another found a strong connection between an altered gut microbiome and prevalence of psoriasis.
Often, when we look below the surface of these (and other!) skin conditions, we also find gut inflammation and/or a dysfunctional intestinal barrier, which can allow toxins and other harmful microorganisms toleak into the bloodstream, triggering an aggressive immune response, which can manifest on the skin.
To understandwhythese two organs have such a great impact on one another, we can first look at their innate similarities.
Similarities Between the Barriers of the Gut and Skin
You’ve probably heard that the skin is your body’s largest organ. Similarly, the gut microbiomeis considered the largestendocrine organ; and the resemblance doesn’t stop there!
Both organs are jam-packed with nerve endings and blood vessels, which help facilitate immune and neuroendocrine function. The inner surface of the gut and outer surface of the skin are both imbued withepithelial cells,which teach the immune system the difference between helpful and harmful materials.
Because of this similarity, the gut and skin have challenges in common – largely associated with dysfunction in the epithelial barrier. In fact, many autoimmune disorders arethought to be a result of confused epithelial cells, which have a hard time distinguishing between the good and bad and tend to err on the side of caution, attacking everything in sight – even perfectly healthy tissue.
(Case in point: both Inflammatory Bowel Disease (IBD) and psoriasisare characterized by such a dysfunction, as well as an accelerated rate of epithelial cell turnover.)
How Gut Health Affects the Skin
First of all, it’s important to note that thewaysby which the gut microbiome affects the skin’s immune system (and the other way ‘round) are still an object of investigation. That said,several studies have demonstrated the bidirectional link between gut dysbiosis and skin homeostasis imbalances.(Source)
In plain English: science says, when the gut ain’t happy, ain’tnobodyhappy.
A couple of the most prominent theories currently supporting this idea (in addition to the implications ofleaky gut, as mentionedabove) are:
The gut produces a massive array of hormone-like compounds – fatty acids, cortisol, neurotransmitters (like serotonin and dopamine –hello, gut-brain connection), and more. When these compounds are released into the bloodstream in happy moderation, they can have a positive impact on more distal organs, like the skin. When the gut isn’t functioning well, these compounds can become restricted or imbalanced, which may contribute to skin issues.
- How well your gut is able to digest and metabolize foodcan also have a dramatic impact on your skin. For example, theenzymes in the digestive tract have no idea what to do with dietary fiber – but your gut flora do! When those bacteria are healthy and in plentiful supply, they’ll happily consume the fiber, triggering a fermentation process that produces short chain fatty acids, which improve the health of theskin’smicrobiome.
How the Skin Affects Gut Health
Although the relationship between the gut microbiome and that of the skin is consideredbidirectional,there is not a lot of research explaining how modulation of the skin’s immune system impacts gut health. One thing wedo know,though, is that exposure to ultraviolet B (UVB) light drives up serum vitamin D levels, and vitamin Dis the gut microbiome’s best friend.
In fact,research has shown that decreased UVB exposure (and consequent impaired vitamin D production) are contributing increasingly to chronic inflammatory diseases, such as IBS and MS, in the Western world. The good news: the same study showed increased bacteria diversity after just three UVB exposures in participants who had not been taking a vitamin D supplement throughout the winter prior to the study’s start.
How Do Gut Health & the Skin Affect Overall Immunity?
As you may have gathered, there is a delicate and intimate symbiosis between the gut microbiome, the skin, and the body’s immune responses. In fact, the gut contains a whopping70% of the immune system! That being the case, it stands to reason that if you want to tend to your overall immunity, these organs are a great place to start.
Many of the most prominent skin conditions (which are evidence of a compromised immune response)are correlated to imbalances in the skin microbiome. That said, science has found it difficult to determine which is the cause and which is the effect.
Something a bit more clear is the way stress andsystemic inflammation (which often begins with gut health – or lack thereof) diminish the skin’s ability to protect itself. When systemic inflammation is present, the skin produces less of its anti-bacterial front-line defenders, leaving it (and the rest of the body) more vulnerable to malignant invading forces. (Source)
The intestinal tract is ahaven for a diverse assortment of microorganisms that are essential for myriad purposes – not least of which is the metabolization of indigestible complex polysaccharides into vitamins and acids the body uses to reinforce the epithelial barrier.
A strong epithelial barrier keeps microbiota where they belong, protects the gut from inflammation, and helps to keep the body’s immune responses in check.
Gut Health’s Impact on Common Skin Conditions
Being that acne is one ofthemost multifactorial skin conditions going, it can be hard to nail down causes and treatment. Fortunately, it’s also been consistently widespread in the Western world for so long, research is not in short supply.
Acne affects79 - 95% of Western adolescents and40 - 54% of U.S. adults older than 25, but isbasically absent in studied non-Western communities. Primary contributors include skin microbiome composition, hormone imbalance, generally compromised immunity, diet, sebum production, and more.
Knowledge of the connection between acne and gut health is long-standing, beginning with the first formal investigations into the gut-brain-skin axisalmost a century ago. Fast forward to 2018, when one study reported that the gut microbiome of individuals who suffer from acne looks distinctly different from those who don’t. According tothe study:
“Acne patients have decreased diversity of the gut microbiota with lower abundance of Firmicutes and increased levels of Bacteroides. Generally, Clostridium, Clostridiales, Lachnospiraceae, and Ruminococcaceae were depleted in the acne cohort.”
Despite the proven tie between gut microbiome composition and acne, it’s prudent to pause before running for the probiotics. Although findings to date are encouraging, limitations related to both products used and study design mean no one can sayfor surethat supplements intended to treat bacteria imbalances can make any substantial difference for acne patients.
Atopic Dermatitis (AD)
AD is the one of the most common inflammatory skin diseases, affecting up to20% of children and1 - 3% of adults worldwide. An individual’s likelihood of developing AD is heavily influenced by genetics, environment, and diet, but there is also a strong association with abnormal gut microbiota.
Studies have shown that patients with AD tend to have greater prevalence of Faecalibacterium prausnitzii, as well as Clostridium and Escherichia coli – both of which can contribute to inflammation. The same patients were found to have lower levels of Akkermansia, Bacteroidetes, and Bifidobacterium, and butyrate-producing bacteria, likeCoprococcus.
By contrast to acne, researchhassubstantiated the incorporation of probiotics – particularly Lactobacillus and Bifidobacterium – into AD treatment regimens.
Psoriasis is an immune-mediated inflammatory disease (IMID) and one of the most common chronic skin conditions, affectingmore than 100 million individuals worldwide. Genetics, lifestyle, stress, and environment all contribute to an individual’s likelihood of developing psoriasis.
It’s extremely common for psoriasis patients to report one or more coexisting conditions, leading researchers to categorize it as a systemic disease rather than one localized to the skin.
As you may have guessed, many of these tagalong conditions have been shown to begin with gut health issues, including:
- Decreased surface in the jejunum (the part of the small intestine primarily responsible for nutrient absorption)
- Intestinal infiltration of lymphocytes (which has alsobeen tied to gluten sensitivity)
- Lactose intolerance
- Compromised intestinal/epithelial integrity
Probiotics have been found to be an effective addition to psoriasis treatment plans!One study proved a combination of strains to reduce symptoms, with fewer relapses – even 6 months post-intervention.
Another study, conducted in 2012, suggested conclusively that an antibody used for the treatment of psoriasis could be used to effectively diminish symptoms of Crohn’s Disease – an inflammatory gut condition – further evidencing the validity of the gut-skin axis.
What Factors Affect Gut and Skin Health?
OK – we know our gut, skin, and overall immunity are inextricably tied. Now, we’ll explore the primary contributors to compromised gut and skin health.
Genetic Predisposition & Overly Hygienic Lifestyle
Whether by way of inherited immune dysfunction or microbiota concentration unique to your family tree, inflammatory diseases of the gut and skin have been shown to be susceptible to genetics.
Additionally, modern health protocols – particularly in the Western world – have created a more sterile existence, which prevents innate microbial stimulationandcan lead to increased prevalence of inflammatory diseases because of reduced exposure to microbes. (Source)
This is abigone. The Western diet – characterized largely by highly processed foods high in salt, sugar, fat, and low in nutrient density – isstrongly associated with inflammatory disorders.
Individuals with bonafide gluten sensitivity or other serious food allergiesoften simultaneously experience autoimmune diseases of the skin, like psoriasis.
For glowing gut and skin health, ditch (or…go easy on) the simple carbs and high-fat meals and opt for:
A diverse, nutrient-dense diet. We havehundredsof species of bacteria in our gut, and many of them – get this – actually have differing food preferences! A variable diet ensures that everybody eats.
All the fiber. One thing all bacteria have in common?Theylovefiber. Eating plenty of plant foods – such as fruit, veggies, and whole grains – will make sure they get enough.
Omega-3s. Omega-3s pump up hydration and enhance the skin’s barrier function. (Hello, strong epithelial cells!) Most of the foods richest in Omega-3s are fish- or nut/seed-based. Think: salmon, fish oil, walnuts, and chia seeds.
Fermented foods. You probably know this one. Fermented foods – such as yogurt, kimchi, and high-quality kombucha – contain their own beneficial bacteria, which can reinforceyourbacteria and assist with digestion and nutrient absorption.
Bitter plants. Bitter plantscan have a positive effect on digestive, endocrine, and autoimmune health. They’re often used to aid in digestive function, detoxify the liver and gallbladder, regulate hormone secretion, and even repair the gut wall. Bitters can be consumed via familiar tea herbs – like chamomile and dandelion – as well as leafy greens, like arugula and kale.
Skin conditions are often notskin deep. The gut-skin axis can help us make important connections between the health of our gut and skin, arm us with information essential for the care of both, and help us live our mostglowylives.