The skin microbiome, sometimes called the skin flora, is the term for the trillions of bugs that live on our skin. There are 1,000 different bacterial species and up to 80 different fungi species. Some of these are also residents of 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.
How does it play a role in our health:
Communicates with our immune system.
We once 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, which were found all the way to the subcutaneous fat layer. While the researchers noted that more studies are needed, it appears that the most intimate communication between the microbiome and our immune system takes place at this layer.
- Protects us against infection.
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 the growth of pathogens.
- Tempers inflammation.
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.
- Protects us from environmental aggressors.
The microbiome also aids in wound healing, limits exposure to allergens, minimizes oxidative damage, and keeps the skin plump and moist. In fact, new research shows that it can protect us from harmful UV rays.
How is the microbiome compromised, and what happens:
You're probably familiar with the idea that loads of antibiotics, other medications, and a poor diet can damage the gut microbiome. There's a lot of research to support this important concept. Ditto for the skin microbiome. Use of soaps are important for hygiene and protecting us against sickness—but it does contribute to skin dysbiosis and antibiotic resistance, thus stoking various skin conditions, research shows. An imbalanced microbiome, or skin dysbiosis, is associated with many health conditions, including psoriasis, allergies, eczema, contact dermatitis, acne, poor wound healing, skin ulcers, dandruff, yeast and fungal infections, rosacea, accelerated skin aging and much more.
It is compromised by two factors: what you put on our skin, and what you put in your body.
- You're using the wrong products
So if you're addicted to "clean," you could be damaging your skin microbiome. Take soap and sulfates, for example: By their 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 up to about 10. Thus, we may actually be damaging our microflora with soap or other alkaline topical products and setting the stage for increased risk for skin issues.
- Your gut microbiome is compromised, too.
New research shows that anything damaging to your gut microbiome also influences what's happening to the skin. It's called the gut-skin axis, and scientists are just beginning to understand the connection. To date, much of the research has been done on the gut-acne connection, but the connection is strong: "The lines of communication, as mediated by gut microbes, may be direct and indirect, but ultimately influences the degree of acne by a systemic effect on inflammation, oxidative stress, glycemic control, tissue lipid levels, pathogenic bacteria, as well as levels of neuropeptides and mood-regulating neurotransmitters.”
3. You over-do it with skin care in general.
While this is a very recent area of study and hypothesis, most dermatologists and experts are coming to the understanding that the very act of applying too many skin care products has the potential to damage our skin barrier and throw our biomes out of whack. This is likely because potent activities in topicals change the behavior of the skin, and therefore the bugs that live on it.
- Modern lifestyle.
It's good to get outdoors and in nature for your physical health, mental health, and it turns out, your microbiome. And unfortunately, people are increasingly living in urban environments—some without regular access to green parks, meaning human micro floras are becoming less diverse overtime.
In fact, research finds that contact with nature—or the lack of contact—directly influences your microflora diversity. "In industrialized countries, non-communicable diseases have been increasing in prevalence since the middle of the 20th century," the study elaborates. "While the causal mechanisms remain poorly understood, increased population density, pollution, sedentary behavior, smoking, changes in diet, and limited outdoor exposure have all been proposed as significant contributors.
Can topical biotic ingredients help?
Topical biotics—like pre-, pro-, and postbiotics—are a growing area of research and development. Many brands have come out with products and collections intended to help nurture the skin's microbiome. These ingredients typically are toward barrier support and nurturing a thriving microbial community—though, of course, the ingredients do so to varying degrees. (Like most skin care items, some products work well, while others are just hype. Biotic skin care is no exception.) This branch of skin care typically comes down to three categories.
Prebiotic : Your microbiome needs a certain amount of nutrients to help it keep on doing its job. You can think of prebiotics as food for probiotics. Look for plant sugars, algae, and minerals.
Probiotics : Probiotic formulas contain strains of the bacteria found naturally on the skin, such as Lactobacillus or Bifidobacterium. These may help reduce inflammation and calm skin
Postbiotics : Postbiotics are the latest, most advanced iteration on biotic skin care. Researchers have been able to identify very important outputs fermented from the bacteria living on our skin. These are things such as antimicrobial peptides and short-chain fatty acids. The idea here is that rather than replanting the bacterial strains (as in probiotics) or feeding the strains we have naturally (prebiotics), postbiotics do the work and supply skin with these natural byproducts from the start.
However, it's just about using topical biotics—in conjunction with these, you must also use hydrating and barrier supporting ingredients, as well as skipping harming ingredients (like harsh soaps and surfactants.) Finally, if you are one to DIY, research also shows that kefir or yogurt on skin also benefits the microbiome.