The Gut-Skin Axis & Acne

How Functional Medicine Uses New Research for a More Effective Treatment Approach to Acne

Acne vulgaris is the most common skin disorder in the Western World and 8th most common disease in the world.

Acne vulgaris affects 90% of people aged 15-25, yet is entirely absent in the hunter-gatherer populations and in those living a non-western lifestyle.

What can be learned from this stark discrepancy?

We’ll unravel this question by the end of the article, and the contrast will start to make a lot of sense. Until recently, acne has been treated as a condition of the skin only, primarily through the use of topical therapeutics and sometimes oral antibiotics. When acne is severe, it is not simply a cosmetic nuisance. It can lead to permanent scarring and disfigurement and a notably reduced quality of life due to a lack of self-confidence and engagement in social settings. 

Acne Treatment Options

Current treatment options have variable results in treating acne, but those that are most effective have a high cost when it comes to adverse side effects. Medications like isotretinoin and oral antibiotics may temporarily relieve symptoms, sometimes drastically, yet the resulting damage to the host can be worse than the initial disease and ultimately does not promote health and longevity of acne-free skin.

Emerging research has found not only associations, but a direct and bidirectional, causal relationship between the skin and the gut microbiome, called the gut-skin axis. The implications of this new research inform new options for treating acne and other skin disorders by addressing the bacteria in the gut and the communication between the gut and the skin.

Functional medicine is ahead of the game in its individualized approach to gut testing and treatment planning. If you’re struggling from acne and haven’t been able to resolve it, the deeper reason may lie in this gut-skin axis. 

In this blog we will discuss what acne really is, what is going on in the bacteria of the skin, why the gut bacteria is so important in relationship to acne and skin, and what can be done to treat acne based on the new research. Let’s take a look!

What Actually Is Acne

All of us have seen acne, and statistically most of us have probably experienced it during our teenage years, so we have a general understanding of its presentation. We see red, inflamed lesions that are often pus filled and painful, and sometimes it’s just clogged pores and blackheads. We experience acne most often on the face or the back, and it is unsightly and difficult to cover up, even with makeup.

But what is actually happening here?

Is acne formation really just due to forgetting to wash your face one night, or are there other factors at play?

Acne is one of the most complex skin disorders and has a multi-faceted mechanism of action which we will explore below. It has long been described as a chronic skin condition involving abscesses and inflammation as a result of increased sebum production, sebaceous gland stimulation and proliferation, and keratinocyte obstruction of the excretion ducts. It is a manifestation of the innate immune system, which is primarily regulated by the skin and the gut (including what we put on or into these systems).

Other factors such as stress and neurotransmitters are also important to consider, but ultimately these are connected to and influenced by the skin-gut axis as well. To start with, let’s take a closer look at the skin itself. 

Acne and the Skin Microbiome

It’s pretty easy to make the connection between bacteria on the skin and the formation of acne lesions, which is why we’ve had research on the skin microbiota and acne connected for decades. 

Cutibacterium Acnes (c. acnes) was first observed in 1896 and makes up to 90% of the bacteria in the most sebum rich sites on the body, most notably the face, chest, and upper back. We have the most c. acnes in our teenage and early adult years before it tapers off while we age.

But it’s not so simple a matter as the more c. acnes bacteria the more acne. In fact, c. acnes is considered a commensal, or helpful bacteria, that helps prevent staphylococcus aureus and streptococcus from colonizing, and also maintains a healthy pH balance with the release of free fatty acids. Healthy, acne free patients have plenty of c. acnes in their sebum.

So why do we blame this bacteria for our acne woes?

It seems that rather than the amount of c. acnes being the critical factor in the development of acne, it is the delicate balance of its various strains. When out of balance it can induce and worsen inflammation on the skin by increasing the activity of cytokines through the stimulation of adaptive immune responses.

Acne patients were found to have the most virulent strains of c. acnes, which cause inflammation and deterioration of the skin barrier, and draw in neutrophils and monocytes to the hair follicle, and excessive sebum and bacteria to the dermis. These strains are also more resistant to antibiotics, and they contain biofilm that protects them from antimicrobial agents and the inflammatory cells from the patient. 

So, in summary, the bacteria on healthy skin exists in a particular balance that maintains the integrity of the skin barrier so it can serve as a first line of defense for the immune system as well as acting as a physical barrier against pathogens. When the microbial balance and diversity is disturbed, an inflammatory immune response is activated and leads to overproduction of sebum, sebaceous gland proliferation, and clogging of ducts.

This can be triggered by environmental factors such as the humidity and temperature, cosmetics and other topical formulas, as well as sun exposure. That said, many of you will likely have tried to do everything “right” from the outside, but still suffer from pervasive acne. This is likely due to other important causative factors, such as the influence from the gut! Let’s check that out next. 

Acne and the Gut Microbiome

While it’s often necessary to address the skin directly with topical therapeutics, the gut may be the most important factor to consider for long-term resolution of skin diseases like acne.

The gut-skin axis is a bidirectional, direct pathway between the gastrointestinal tract and the skin, which implies that skin issues and gut issues are not simply correlated, there is an actual causative relationship between the two.

Read further on the gut-skin axis here. For a quick recap we can think of the gut influencing the skin in two main ways; indirectly by modulating systemic immunity, and directly when there is disruption in the intestinal barrier and gut metabolites travel to, and accumulate in, the skin. 

When we’re considering acne specifically, the mTOR (mammalian target of rapamycin) pathway is the key focus. mTOR is a key regulator of many metabolic functions and influences the gut bacteria and the intestinal barrier.

When the balance of ‘good’ and ‘bad’ bacteria is off in the gut, mTOR may ramp up the metabolism and inflammatory processes of the host which in turn may disrupt the intestinal barrier even more, leading to aggravation of acne symptoms. mTOR is also a key player in maintaining homeostasis in the skin layer. It responds to specific nutrients ingested into the gut and helps form the epidermal layer of the skin. 

So we can see that mTOR is directly involved in both the gut and the skin barriers. So what’s one of the main ways that the mTOR mechanisms get disrupted in the first place? Since we know it responds to specific nutrients in the gut, it’ll make sense to learn that diet plays a big role in acne!

Acne and Diet

As we mentioned in the opening of this article, while acne is rampant in the West, it is practically non-existent in non-western communities such as hunter-gatherers. This isn’t surprising when we look at the differences in the diet.

The most striking difference is that of ultra-processed food consumption. The Western diet is high in ultra processed foods as well as refined sugar, conventionally processed dairy, and inflammatory vegetable oils. It is also often low in fruits and vegetables, and even good quality animal protein is paired with refined carbohydrate sources and processed oils.

This way of eating seems to reduce the diversity of gut bacteria which leads to impairment of the intestinal lining as well as a thinner intestinal mucosa. As a result, there is an increase in inflammatory cytokines causing systemic inflammation as well as metabolites from the gut traveling directly to the skin. 

Another way the Western Diet disturbs the gut bacteria is by way of insulin and insulin like growth factor-1. This pathway is disturbed by diets rich in foods that are high on the glycemic index, as well as excess processed fats and low fiber intake. In turn, the quantity and diversity of gut bacteria is reduced, resulting in the same inflammatory processes that ultimately lead to acne. 

You may have also noticed that acne tends to flare up during periods of high stress and anxiety.

Could the gut possibly be at play here? You bet! Stress has a similar effect as the others mentioned above in that it ultimately alters the gut bacteria in such a way that intestinal permeability is increased and skin inflammation results. So what is there to do?

Why Using Antibiotics for Acne May Be a Problem

Acne has been treated using both topical and oral antibiotics for several decades, primarily with tetracyclines, clindamycin, and macrolides. While these don’t cure the disease, they can be effective in suppressing acne symptoms and toning down inflammation.

However, even with somewhat satisfactory results in the short term, there are issues with this treatment method that are very important to consider. The effect of antibiotics will only work while using antibiotics, and studies show that the level of c. acnes that declines during treatment will go back to the baseline within weeks of stopping treatment. This leads people to use antibiotics for a much longer time period.

This is also problematic as ongoing use of antibiotics eventually leads to major disruption in the gut microbiome which, as we’ve discussed, is a cause in itself of acne. Researchers also found that only 4 weeks of antibiotics led to a significant increase in the bacteria Pseudomonaswhich leads to a gram-negative folliculitis skin infection.

This is commonly observed in acne patients who use antibiotics. Worse still, c. acnes is becoming increasingly resistant to antibiotics, rendering the treatment less and less effective as time goes on yet still carrying the same side effects. 

Ideally, acne patients can avoid using antibiotics altogether and instead of further disturbing their gut bacteria, actually begin to balance it. Let’s check out the other options. 

Treatments for Acne Based On New Research

Aside from antibiotics, there are other common acne therapies that target different mechanisms. Topical retinoids and benzoyl peroxide work to maintain c. acne levels and prevent further imbalance. Azelaic acid blocks the protein synthesis in the c. acnes bacteria without resulting in bacterial resistance.

Generally, topical treatments that can reduce some amount of c. acnes bacteria will help promote more bacterial diversity in the skin. That said, none of these are addressing causes of acne beyond the superficial layer, and they won’t necessarily work if they don’t address the individual patient’s imbalance in bacteria. As we learned earlier, it’s not always about the amount of c. acnes present but rather the balance and interplay of the different phylotypes.

In addition, many popular acne treatments such as isotretinoin can be harsh on the skin and lead to dry skin and rashes or even more serious issues such as depression, chest pain, vaginal discharge, thinning hair, birth defects, gastrointestinal disorders and many more. When these treatments are discontinued, the patient may end up in a worse circumstance than before they began. 

UV light is one well studied therapy that appears to have an anti-bacterial effect as well as lowering inflammation and having an overall beneficial effect on the c. acnes presentation within the rest of the skin microbiota. Again, this is a topical treatment so it may not be a sufficient method on its own if there are other factors at play. 

Pre and probiotics are another option that have been studied for quite some time, with newer research emerging on their beneficial effect on the skin. This is no surprise after everything we’ve covered on the gut-skin connection and acne. Both pre and probiotics appear to modulate the gut microbiome in such a way that promotes more beneficial bacteria and helps to control harmful bacteria.

Historically they have been effective in reducing symptoms of IBD and other gastrointestinal disorders and are now being shown to have benefits for those suffering from skin disorders such as acne. In addition, probiotics play a role in increasing insulin sensitivity which in turns helps to regulate inflammation in the skin through the gut-associated lymphoid tissue. 

There are many different treatment options on the market that claim to cure acne and improve skin appearance, but it’s becoming clear that many of these have shortcomings that can be ineffective or detrimental.

Even the more promising therapies with less side effects, such as light therapy and probiotics, won’t necessarily address a specific patient’s gut imbalance that might be the root cause. This is where it is critical to have personalized care.

Functional medicine is paving the way for acne treatment with individual testing and specific treatment plans that address acne patient’s needs starting at the deepest layer. 

We now know how key the gut microbiota is in both the cause and the resolution of acne. While topical treatment may be very helpful, the most thorough and long-lasting acne treatment will likely involve a plan to treat the gut through diet and supplementation as well as some environmental alterations. Get in touch with a functional medicine practitioner today to start treating your acne from the inside out. 

Dr. Jenny Bisset
Founder of The Bisset Method
JB Wellness
Chinese + Functional Medicine

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