Acne is a common chronic health condition that affects millions of adolescents and young adults. The direct cost of acne in the United States exceeds $1 billion annually. Despite these high medical care costs, treatment failure rates are as high as 81%. (16) These statistics call for an alternative and more effective treatment approach, highlighting the need to recognize how the gut-skin axis is connected to acne. Acknowledging gut health as a crucial factor in skin conditions may be the missing piece needed for improved dermatological outcomes. 

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What is Acne?

Acne vulgaris, more commonly called acne, is the most common skin condition in the United States, affecting 50 million Americans annually. Acne is characterized by the formation of lesions, called pimples or zits, on the skin. It often occurs during puberty due to hormonal changes, leading to increased oil (sebum) production in the skin. (26) 

Pores are small openings in the skin that release oil and sweat. Acne forms when hair follicles become clogged with sebum and dead skin cells. This creates an environment for bacteria to thrive, causing inflammation and acne lesions. (26) 

There are two main types of acne: inflammatory and noninflammatory. Inflammatory acne includes red, swollen lesions such as papules, pustules, nodules, and cysts, which can be more severe and prone to scarring. Noninflammatory acne consists of blackheads (open comedones) and whiteheads (closed comedones), which are milder and typically do not cause swelling. (12) 

Conventional first-line treatments for acne include topical and oral medications. Topical treatments often involve benzoyl peroxide, retinoids, and antibiotics. Benzoyl peroxide helps to reduce bacteria and inflammation, while retinoids promote cell turnover and prevent clogged pores. Topical antibiotics work by locally eliminating bacteria on the skin. (12, 27) 

Oral antibiotics, such as tetracycline, doxycycline, or minocycline, may be prescribed for more severe cases of acne. These antibiotics help to control inflammation and bacterial growth. Females may be prescribed oral birth control pills or spironolactone to regulate hormonal imbalances contributing to acne formation. (12, 27)

While these treatments can be effective for some, they have limitations and potential side effects. Topical treatments may cause skin irritation, dryness, or redness, especially during the initial stages of use. Oral antibiotics can lead to side effects such as gastrointestinal upset and increased sensitivity to sunlight. Prolonged use of antibiotics raises concerns about antibiotic resistance. While these interventions may address the symptoms of acne, they often don't target the root cause of the skin lesions. (27) 

Oral isotretinoin (Accutane) is often prescribed when other treatments have been ineffective at improving acne lesions. Isotretinoin has an FDA black box warning for its potential to cause life-threatening congenital disabilities; therefore, it is contraindicated for patients who are or may become pregnant. Other side effects associated with isotretinoin include hepatitis, pancreatitis, osteopenia, dry skin/eyes, nosebleeds, and depression. (12)

The Gut-Skin Axis

The gut-skin axis is a concept that highlights the bidirectional relationship between gut and skin health. It underscores the idea that the condition of the gastrointestinal tract can significantly influence the appearance and overall health of the skin. This connection is mediated through various factors, with the gut microbiota playing a crucial role. 

The gut microbiome is a diverse community of microorganisms residing in the digestive system that actively communicates with the immune system and other organs, including the skin. An imbalance in the gut microbiota, known as dysbiosis, can contribute to systemic inflammation and breaches in skin barrier function. Additionally, increased intestinal permeability, often called "leaky gut," allows substances like bacteria and toxins to enter the bloodstream. This can trigger immune responses and inflammation that may manifest on the skin. Dysbiosis has been associated with numerous inflammatory skin conditions, including eczema, rosacea, and psoriasis (35). 

Understanding the profound impact of gut health on skin health becomes crucial, especially in conditions like acne, given the intricate and multidirectional interactions between the gut microbiota, immune system, and endocrine system. The gut, hosting up to 80% of the body's immune cells, becomes a central hub where these systems converge. The balance of microorganisms in the gut microbiome actively shapes immune responses, and dysbiosis is implicated in steering the immune system toward a pro-inflammatory state. (9) 

Moreover, the relationship extends to hormonal regulation, as microbial metabolites, including short-chain fatty acids (SCFAs) and beta-glucuronidase, play a role in modulating hormonal systems. Dysbiosis can disturb the equilibrium of these metabolites, giving rise to conditions such as insulin resistance, estrogen dominance, and androgen overload. These imbalances are intricately linked to the pathogenesis of acne. For instance, insulin resistance is associated with increased sebum production, while estrogen and androgen imbalances influence factors like keratinization and sebaceous gland activity, contributing to acne development. (9)

Gut Health and Acne: The Research

While research on the link between gut health and acne is ongoing, several studies have explored the association between gut dysbiosis, inflammation, and the role of specific gut bacteria in acne development. In a 2018 study by Deng et al., the intestinal microbiota of 43 treatment-naïve patients with varying degrees of acne was compared to that of 43 age- and sex-matched healthy controls. The study revealed a decreased diversity of commensal flora in acne patients. At the phylum level, patients with acne exhibited a reduction in Firmicutes and an increase in Bacteroidetes. Notably, there was a significant decrease in Clostridial families such as Lachnospiraceae and Ruminococcaceae, known for their potential benefits and production of SCFAs.

A more recent study by Deng's research group revealed gender-specific dysbiotic patterns in patients with acne. At the phylum level, men with acne exhibited a considerable increase in Firmicutes and a decrease in Bacteroidetes compared to healthy control men, differences not observed in women. At the genus level, men with acne showed reductions in 18 bacterial genera. Women with acne exhibited an increase in Clostridium sensu stricto and a decrease in Oscillibacter and Odoribacter. Furthermore, the study highlighted gender-specific alterations in fecal metabolites. Men with acne demonstrated impaired fatty acid metabolism, while women with acne displayed impaired amino acid metabolism.

Studies dating back to the 1900s have shown increased intestinal permeability and endotoxemia in patients with acne. Dysbiosis can lead to increased intestinal permeability, allowing the translocation of bacteria and their toxic byproducts into the bloodstream. This microbial breach triggers systemic inflammation, contributing to the inflammatory pathways observed in acne lesions. (30) 

Furthermore, clinical trials have assessed the effect of probiotics on acne, noting positive clinical outcomes. Treatment using various combinations of oral and topical probiotics, including Enterococcus faecalis, Lactobacillus plantarum, Bifidobacterium bifidum, and L. acidophilus, have significantly reduced acne lesion counts and severity. Additionally, some of these studies have shown greater patient tolerance to oral antibiotic therapy by reducing side effects associated with oral antibiotics. (23) 

Dietary Interventions for Acne

Our dietary choices influence the microbiome's composition and intestinal inflammation levels. Western diets high in saturated fat, processed foods, and sugars decrease microbial diversity and increase intestinal permeability, leading to increased gastrointestinal and systemic inflammation levels.

Conversely, plant-based diets that limit processed foods promote a healthy microbiome. The Mediterranean diet, characterized by a high intake of fruits, vegetables, whole grains, legumes, nuts, and olive oil, with moderate consumption of fish, poultry, and red wine, has several positive effects on gut health. Studies suggest that adherence to the Mediterranean diet may contribute to a more diverse and balanced gut microbiota and support the gut barrier's function. The anti-inflammatory components of the Mediterranean diet, such as omega-3 fatty acids, help modulate the gut immune response, reducing inflammation. The Mediterranean diet's emphasis on high-fiber foods may contribute to higher SCFA production, providing energy for the cells lining the colon and exhibiting anti-inflammatory effects. (31) 

Specific to acne, studies suggest that following a low-glycemic, dairy-free diet may improve acne outcomes. In a study involving more than 2,000 participants who adhered to a low-glycemic diet for weight loss, 87% reported a reduction in acne lesions, and 91% indicated a decreased need for acne medication as a result of the dietary interventions. Another study found that 44% of women who drank at least two glasses of cow's milk daily were more likely to have acne.

Functional Medicine Lab Testing

Functional medicine testing for acne is a helpful way to gain important insights into the underlying imbalances contributing to acne. Based on lab results, functional medicine doctors will work with patients to create personalized treatment plans that incorporate a variety of complementary and integrative modalities. 

Gut Assessment

Given the strong association between poor gut health and acne, lab tests for gut health are critical to a comprehensive evaluation of acne. 

A comprehensive stool analysis evaluates the microbiome composition, identifying the presence of beneficial and harmful bacteria, parasites, and yeast. It provides insights into the overall microbial balance, microbial metabolites, and inflammation levels. 

Increased intestinal permeability may allow toxins and undigested particles to enter the bloodstream, potentially triggering systemic inflammation associated with acne. LPS, or lipopolysaccharide, is a component of the cell wall of certain bacteria. Increased levels of LPS in the bloodstream may indicate compromised gut barrier function. Patients with acne often have elevated levels of LPS endotoxins in the blood. Intestinal permeability tests, the Array 2 by Cyrex Labs, help to qualify and quantify the degree of gut leakiness manifesting as inflammation and acne. (3) 

Food Sensitivities

Food sensitivities are implicated in intestinal hyperpermeability and acne. Food sensitivity panels analyze various immune proteins that indicate adverse reactions to foods. These results identify trigger foods and help customize elimination diets for gut-healing and acne treatment protocols.   

Inflammation

Poor gastrointestinal health can lead to an increased risk of systemic inflammation. In addition to gut-specific markers of inflammation and immune activation included in a stool analysis, CRP and ESR are commonly used to quantity and monitor systemic levels of inflammation.

Hormones

Hormonal imbalances, particularly in androgens and estrogen, are linked to acne development. Assessing hormone levels through blood, urine (like the DUTCH Complete by Precision Analytical), or saliva tests like the Saliva Hormone Blueprint by Access Medical Laboratories can help identify potential contributors to skin issues.

Holistic Treatment Approaches

An integrative approach to acne addresses its root causes, as identified during a thorough patient history intake and lab testing, using a variety of holistic acne treatments.

Dietary adjustments in acne management focus on embracing anti-inflammatory eating patterns while restricting or excluding foods known to exacerbate the condition (discussed above). In cases where food sensitivities are suspected as a potential underlying cause, practitioners often recommend an elimination-rechallenge diet. During the elimination phase, individuals temporarily remove potential dietary triggers to provide a respite for the gut, aiding the gut-healing process and lowering inflammation levels. The subsequent rechallenge process helps confirm specific sensitivities and offers valuable insights to patients, allowing them to recognize the direct impact of diet on their symptom presentation. (26) 

Stress can significantly impact the gut and contribute to acne through various interconnected pathways. Stress triggers the release of hormones such as cortisol and adrenaline, which can influence the gut-brain axis, affecting gut function, microbial composition, and permeability. Additionally, stress induces changes in sex hormone balances. A cross-sectional study found that stress severity strongly correlated to acne severity. Therefore, incorporating stress-management techniques, including mind-body exercises, counseling, and herbal supplements, becomes an important aspect of a holistic acne treatment protocol. 

The relationship between sleep and gut health is intricate. Adequate sleep supports the balance and diversity of the gut microbiome. Disruptions in the sleep-wake cycle, such as inadequate sleep duration or irregular sleep patterns, can adversely affect the gut microbiota, leading to dysbiosis. In turn, an imbalanced microbiome may impact sleep quality, creating a cyclical relationship. Prioritizing good sleep hygiene supports the intricate interplay between sleep, the digestive system, and skin health. (24, 33) 

Addressing the Microbiome

Incorporating specific dietary and lifestyle strategies is crucial in supporting a healthy gut microbiome. First and foremost, a diet rich in fiber from diverse plant sources promotes the growth of beneficial gut bacteria. Probiotic-rich foods, such as yogurt, kefir, sauerkraut, and kimchi, introduce live beneficial bacteria to the digestive system, supporting microbial diversity. Prebiotic foods like garlic, onions, and bananas fuel these beneficial bacteria. (25) 

Probiotic supplements can be considered, especially during or after antibiotic treatment or for those with specific gut health concerns. Studies dating back to the 1960s have shown promise for probiotic supplementation in treating acne. In one study, L. acidophilus and L. bulgaricus oral probiotics improved acne in 80% of the subjects with acne, especially those with inflammatory lesions.  

Functional medicine providers often implement a 5R Protocol with their patients to restore gastrointestinal and microbiome health. "5R" stands for Remove, Replace, Reinoculate, Repair, and Rebalance. The protocol involves removing irritants and potential triggers from the diet and replacing them with nourishing foods and supplements that support digestive function. This is followed by introducing therapeutic nutrients to aid gut healing and reinoculating beneficial gut bacteria with probiotics. The protocol also calls attention to lifestyle modifications and practices to maintain long-term gut health. (8) 

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The Gut-Based Approach to Healing Your Acne

Recognizing gut health's role in acne development underscores the need for a holistic approach to skin wellness. Embracing gut health for clear skin is essential, as research increasingly highlights the intricate interplay between the gut microbiome, inflammation, and hormonal balance in acne development. Integrating gut-based approaches, such as dietary modifications, probiotics, and lifestyle changes, can offer a holistic perspective to acne management.