Your skin is on display to the world and plays a significant role in your overall health. The skin makes up 15% of the total body weight of adults and carries out an important barrier function as well as wide-reaching effects throughout the body. Microbes found throughout the human body work synergistically to impact many physiological processes, with those found on the skin and in the gut having many impacts on skin health. 

Probiotics are beneficial organisms that are taken to enhance and support the healthy balance of microbes in the body. Both oral and topical probiotics can help treat certain skin diseases, such as acne, atopic dermatitis, rosacea, photoaging, psoriasis, and wound healing.

Topical probiotics allow for the application of beneficial organisms to the surface of the skin. This can help to prevent the overgrowth of pathogenic bacteria, balance the immune response, and soothe inflammation.

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What Are Topical Probiotics?

The skin is the human body’s largest organ and external barrier to the world. It is inhabited by microorganisms, including bacteria, fungi, viruses, and mites that make up the skin microbiome. You acquire your unique skin microbiome at birth, and it remains dynamic throughout your life.

The skin microbiome has two main groups of microbes, the fixed resident microbiome, which is the foundation and can replenish itself after being disturbed, and the transient microbiome, which changes and appears for a few hours or days depending on the environmental conditions. These serve various purposes, including producing antimicrobial and anti-inflammatory substances, protecting the skin from colonization with pathogenic microorganisms, boosting the skin’s immune function, contributing to the sebum barrier, and preventing inflammatory conditions and skin cancers. 

Various areas of the skin have different microenvironments which support a unique balance of microbes. Overall, the most common phyla residing on the skin include Actinobacteria, Firmicutes, Proteobacteria, and Bacteroides, with Corynebacteria, Propionibacteria, and Staphylococci making up the most common genera of bacteria. The microbes which inhabit the skin have adapted to utilize the lipids and sebum on the skin to allow them to live in the dry, desiccated environment of the skin’s surface.

Probiotics are live microorganisms that are taken or applied to the body in hopes of maintaining or improving the balance of beneficial microbes. Topical probiotics are formulations that allow for the application of such microbes to the skin’s surface. This exogenous application of beneficial bacteria to the skin promotes a positive bacterial balance to alleviate inflammation and the skin conditions it can cause. Under proper conditions, topical probiotics can persist and successfully colonize the skin to favorably shape microbial communities. While still being studied, topical probiotics are considered safe treatments without many of the adverse effects that can occur with some conventional treatment options for skin conditions.

How Do Topical Probiotics Support Skin Health?

Research shows that the topical application of probiotics to the skin has beneficial effects on the prevention and treatment of many inflammatory skin conditions, including acne, atopic dermatitis, and rosacea. In addition, topical probiotics help with appropriate wound healing and are being incorporated into cleansing and anti-aging skincare products. 

These benefits result as probiotic bacteria prevent pathogenic microbes from colonizing the skin while also improving immune tolerance, reducing inflammation, and releasing biochemicals that inhibit the growth of harmful microbes. Oral and topical probiotics benefit the skin by modulating the skin microbiome and gut-skin microbial interactions. Multiple mechanisms seem to be involved in these benefits, including reducing oxidative stress, inhibiting remodeling of the extracellular matrix, inhibiting inflammatory cytokines, and maintaining balance in immune responses.

The topical application of probiotics to the skin helps to support the skin’s natural barrier function at the site of application and also has wider-reaching impacts by influencing inflammation and immune system function. These effects are thought to result from probiotic microbes producing antimicrobial amino peptides that benefit immune responses in the skin and help in balancing out the skin’s microbiome to reduce pathogenic microbes that can contribute to skin inflammation and rashes. 

What Are The Top Benefits of Using Topical Probiotics?

When the skin maintains a balanced level of microbes, it stays healthy and free of excess inflammation. When environmental stresses and other factors cause a shift in the balance of microbes on the skin’s surface, pathogenic microbes can grow out of control and contribute to clinical signs that suggest an imbalance between your skin and its microbiome. These include inflammation, itching, scaling, and other rashes. Topical probiotics help to repair and strengthen the skin barrier, reduce inflammation, and prevent the overgrowth of pathogenic microbes to improve skin health. 

One skin condition where topical probiotics have been shown to have a beneficial impact is acne. Acne develops due to inflammatory changes in the skin, which occur when sebaceous follicles become overly colonized with Cutibacterium acnes (formerly Propionibacterium acnes) and other imbalances in the skin microbiome that can occur with hormonal changes, stress, anxiety, and lifestyle changes. 

These bacteria feed off the lipids produced there and release substances that cause local injury and inflammation that disrupt the skin barrier. Topical probiotics, including L. plantarum and L. acidophilus, reduce acne lesions and inflammatory pustules by inhibiting several inflammatory mediators, cytokines, and related signaling pathways while enhancing the production of ceramides that strengthen and heal the skin barrier function and inhibit skin inflammation induced by Cutibacterium acnes.

Topical probiotics have also been studied for their benefits in ​​atopic dermatitis or eczema. This common chronic inflammatory skin condition is characterized by dysbiosis in the skin microbiome, which has low bacterial diversity and increased S. aureus leading to dysregulation of the skin’s innate antimicrobial immune responses that result in dry, red, scaly skin rashes that can be very itchy. 

A systematic review of the use of various strains of topical probiotics for eczema found that manipulating the skin microbiome with topical probiotics offered promising improvement in skin findings with no serious adverse events or treatment complications.

Seborrheic dermatitis or dandruff causes redness and flaking of the skin due to excess growth of yeast with reduced diversity of the skin microbiome. Topical application of Vitreoscilla filiformis and oral administration of Lactobacillus paracasei probiotics bring about a reduction in erythema, scaling, and pruritis in this condition.

Another inflammatory skin condition where topical probiotics are used to rebalance the skin microbiome is psoriasis. This autoimmune condition causes red, scaling, painful skin lesions due to dysbiosis in the skin microbiome that causes dysregulation of the skin’s immune responses. Psoriatic skin lesions have greater amounts of Streptococcus and a decreased amount of Propionibacterium with a lack of microbial diversity. In addition to restoring the gut microbiome balance with oral probiotics, topical probiotics may help to manage psoriasis.

What Is The Connection Between Gut Health and Skin Health?

The skin and gastrointestinal tract are intertwined and can influence each other via the gut-skin axis. The gut microbiome influences signaling processes that help the skin turnover and keep cells healthy to maintain the integrity of its barrier function. When the balance of microbes in the gut microbiome is disturbed, its communication with the immune system is impaired, triggering increased inflammation in the skin and throughout the body. In this way, the gut microbiome impacts the skin and vice versa through complex mechanisms, including influences on inflammation, immune system function, and more. 

Given this connection, studies have shown that imbalances in the gut microbiome often contribute to inflammatory skin diseases. Antibiotics, prebiotics, probiotics, lifestyle habits, long-term diets, and illnesses can all influence the gut microbiome and its impact on the skin. Studies show that an imbalance in the gut microbiome may result in skin conditions, including acne, psoriasis, eczema, and rosacea. 

Therefore, oral probiotics have been studied and shown to benefit the skin by helping to decrease excess inflammation in these skin conditions as well as tame the autoimmunity involved in skin conditions such as psoriasis and vitiligo. Prebiotics like fiber and other nondigestible carbohydrates nourish probiotic bacteria in the gut.

Functional Medicine Labs to Analyze the Gut-Skin Axis

Testing using a functional medicine approach can help guide the treatment of inflammatory skin conditions by rebalancing the gut-skin axis. Functional medicine laboratory tests can provide an understanding of the balance in the gut and skin microbiome and assess other factors that can contribute to skin health, including inflammation and metabolites that are impacted by microbial balance.

Comprehensive Assessment of Gut Health

The GI-MAP provides a comprehensive analysis of gut health by examining gut microbes, along with markers of dysbiosis, inflammation, and intestinal permeability, via measuring zonulin, a protein that impacts the permeability of the gut lining. Looking at the composition of the gut microbiome in this way measures the balance of pathogenic and commensal bacteria, yeasts, and parasites to identify imbalances in the gut microbiota (dysbiosis), which may be contributing to skin inflammation.

Inflammation Levels

Levels of systemic inflammation that can reflect imbalances in the gut and/or skin microbiomes can be assessed by measuring C-Reactive Protein (CRP), a protein made by the liver as a response to inflammation in the body. Elevated CRP levels reflect systemic inflammation that can occur with dysbiosis in the gut, inflammatory skin conditions, and leaky gut. Repeating CRP measurement over time can help with monitoring treatment with oral and topical probiotics and assessing the effectiveness of mitigating inflammation and improving skin health.

Organic Acids Testing

Organic Acids can be measured in the urine to get a view of the efficiency of various metabolic pathways, including those influenced by gut microbiota. This testing provides a comprehensive view of metabolites formed during the body's cellular processes, including short-chain fatty acids (SCFAs) like butyrate that are critical for maintaining a healthy gut barrier and modulating systemic inflammation to maintain healthy skin health and complement treatment with topical probiotics. 

Functional Medicine Treatments That Complement Topical Probiotics

Since the gut and skin are so connected via the gut-skin axis, diet and lifestyle habits can have a significant impact on skin health and complement the use of topical probiotics. Imbalanced gut bacteria, infections, food allergies, and/or leaky gut can contribute to the underlying inflammation and oxidative stress that occurs in many of the inflammatory skin conditions for which topical probiotics are used. Addressing these factors and the whole person’s health can make treatment more effective and improve quality of life. 

A Mediterranean diet, which emphasizes plenty of whole fresh vegetables and fruit while avoiding processed foods and additives as well as foods that one is allergic to or sensitive to, caffeine and alcohol, is an anti-inflammatory way of eating that can nourish the microbiome and balance inflammation. 

Temporarily eliminating foods that interfere with the gut microbiome's equilibrium and then introducing foods rich in prebiotic and probiotic elements and fermented foods via a Microbiome Diet can help to restore a balanced microbiome and inflammation throughout the body. Focusing on including plenty of probiotic-rich foods like kimchi and sauerkraut and sources of prebiotics like fiber and other nondigestible carbohydrates to nourish probiotic bacteria in the gut helps establish a healthy gut microbiome to complement the restoration of a healthy skin microbiome with topical probiotics. 

Oral probiotic supplements, such as Lactobacillus strains and Bifidobacterium breve B-3 have shown promise in addressing skin conditions such as acne and eczema. An individualized supplementation regimen can be tailored based on the results of comprehensive stool testing, as discussed above.

Industrial trans-fats and refined and hydrogenated oils (e.g., sunflower, soybean, canola, corn, safflower, and other vegetable oils) contribute to increasing the number of harmful microbes (such as Desulfovibrionaceae and Proteobacteria) while suppressing populations of beneficial microorganisms (e.g., members of Bacteroidetes, Lachnospiraceae, and Bacteroidales) leading to inflammation which manifests on the skin. Healing of the skin is also impaired with high-fat diets and alcohol consumption, so removing these from the diet can complement the use of topical probiotics for healing the skin. 

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Summary

There is a growing understanding of the importance of microbes on the skin and how imbalances in this skin microbiome affect skin health. As the science supporting important connections between gut microbes and the skin grows, research is also exploring the importance of the microbes that inhabit the skin. 

The balance of the skin microbiome can be disrupted by exposure to environmental toxins, illness, changes in pH, lifestyle habits, diet, medications, and the use of certain skincare products. Oral and topical probiotics are used to balance the populations of microorganisms within the gut–skin axis and improve the microbiome on the skin. 

Topical probiotics show great promise for reducing inflammatory and autoimmune skin disorders and contributing to skincare and wound healing without adverse side effects. Certain probiotic strains and their metabolites (postbiotics) can strengthen the skin barrier function, reduce inflammation, and improve the appearance of inflammatory skin conditions such as acne and eczema.

Dietary and lifestyle changes can complement the use of topical probiotics to allow the skin to heal and remain in balance. An anti-inflammatory diet that incorporates natural sources of probiotics like kimchi and sauerkraut, along with prebiotic fibers to nourish healthy gut bacteria, can help restore balance to the microbiome and complement treatment with topical probiotics.