We typically think of skin only as it relates to beauty — but it's actually really important to our overall health, too. After all, it's the largest organ in the body, and the major interface between us and pretty much everything outside of us.
Our skin is also home to a vast array of microbes, and research is just now beginning to piece together the important role they play in our health.
As a naturopathic functional medicine doctor, I'm fascinated by the skin microbiome and how it relates to health and disease. Here's the 101 on the skin microbiome and how to care for yours.
Your Skin Microbiome: What It Is + How It Relates to Our Overall Health
Of the 1 trillion bugs on our skin, there are a whopping 1,000 different bacterial species and up to 80 different fungi species.
Some of these critters are also residents in your gut microbiome, including staph, strep and candida species. There are also a few bifidobacterium and lactobacillus species on certain areas of the skin but much less so than in the gut.
The skin microbiome changes depending on the “eco-niche,” or location. The critters also vary depending on the amount of light and whether the area is moist, dry, hairy, or oily. And the microbiome differs with age and gender. For instance, a hormonal, sweaty teenage boy sports a very different microbiome than a sedentary, postmenopausal woman.
Once upon a time, we thought that our microbiome only existed on the surface of the skin and that the deeper dermal layers were sterile. We now know that’s not true. In 2013, scientists did a deep dive into the dermis looking for microbes. And they were identified all the way down to the subcutaneous fat layer! While more research is needed, it appears that it's here that the most intimate communication between the microbiome and our immune system takes place.
From what we can tell, a healthy skin microbiome protects against infection in much the same way a good gut microbiome does, by crowding out overgrowth of pathogenic organisms. The skin microbiome prefers a relatively acidic environment (pH is around 5.0), which also inhibits growth of pathogens.
The microbiome and skin immune system “talk” to each other regularly, dampening inflammation. When the microbiome is out of line, the immune system can release various antimicrobial peptides such as cathelicidin to help balance things out. Likewise, our good bacterial residents can inhibit the release of inflammatory compounds from the immune system.
Newer research in mice suggests that in early infancy, the skin microbiome is involved in inducing “tolerance,” which researchers hypothesize may reduce the incidence of autoimmune diseases later in life. Antibiotic exposure that damages the skin microbiome in infancy may compromise the development of tolerance, allowing for the development of autoimmunity.
The microbiome also aids in wound healing, limits exposure to allergens and UV radiation, minimizes oxidative damage, and keeps the skin plump and moist.
Dirt Is Good: How to Tend to Your Skin Microbiome
You’re probably familiar with the idea that excess cleanliness and loads of antibiotics and other medications can damage the gut microbiome and could increase the risk of allergy and autoimmunity, among other issues. This is called the “hygiene hypothesis,” and there's a lot of research to support this important concept.
Ditto for the skin microbiome. Excess use of antimicrobial hand sanitizers and soaps contributes to skin dysbiosis and antibiotic resistance, thus stoking various skin conditions. An imbalanced microbiome, or skin dysbiosis, is associated with many diseases, including psoriasis, allergies, eczema, contact dermatitis, acne, poor wound healing, skin ulcers, dandruff, yeast and fungal infections, rosacea, and accelerated skin aging.
So if you’re addicted to “clean,” you could be damaging your skin microbiome. Take soap, for example. By its very nature, it’s alkalinizing. That’s how it works to remove dirt and microbes. But recall that our skin microbiome prefers a pH of about 5. At this relatively acidic pH, the healthy microbiome thrives. It’s also understood that the opportunistic bacteria — the dysbiotic players — do better at a higher, more alkaline pH. And soap has a pH of about 10! Thus, we may actually be damaging our microflora with soap and setting the stage for increased risk for skin issues.
What else can affect the skin microbiome? A recent study showed that kids who hand-wash dishes have a lower incidence of allergies compared to those in families that use a dishwasher. That sounds paradoxical given what I’ve just mentioned about soap, but the authors speculate this has to do with the benefits of skin exposure to the microbes on the dirty plates.
Hand sanitizers, topical steroids, and internal medications (such as antibiotics, oral steroids, acid blockers, and nonsteroidal pain relievers) can also directly or indirectly damage the skin microbiome. Plus, anything damaging to your gut microbiome or immune system will likely also influence what’s happening to the skin.
Finally, while there is less research in the area of toxins and the skin microbiome specifically, we can infer that parabens, phthalates, sulfites, and others are also likely damaging.
Here's what else you can do to keep your skin microbiome healthy:
1. Eat healthy and stay hydrated.
I recommend good fats, proteins, carbohydrates, colorful vegetables, and clean water. Keep processed foods and extra sugar out of the diet. Research shows that what you put in your mouth indeed influences your skin and skin microbiome in many ways. Keep food organic as much as possible.
2. Identify and remove trigger foods.
3. Take care of your gut.
Arguably, all skin issues are influenced by the gut microbiome and gut health in general. I recommend taking a daily high-quality probiotic. Much research exists on the use of probiotics in preventing or treating many skin conditions.
4. Minimize the use of hand sanitizers and soaps.
Let your microbiome thrive! If you find that reducing your showers and soaps leads to you becoming too oily or odoriferous, I recommend consulting with a functional medicine doctor to find out why. And there are many nontoxic, natural moisturizers and cleansers you can try instead.
5. Work up a sweat a few times a week.
If you’re eating well, the sweat you produce is likely a fortifying prebiotic for the skin microbiome.
6. Keep your stress levels in check.
Just like elsewhere in the body, stress likely negatively influences what’s happening with your skin. Find a stress management method that works best for you, such as yoga or meditation.
7. Try a topical probiotic.
This is a new, growing area. In my practice, I recommend patients try applying a probiotic powder mixed with coconut oil or shea butter to their skin. Emerging research on using kefir or yogurt on skin looks promising as well.