Part 1 - Skin - Are your products making you sick?

We typically think of skin only as it relates to beauty—but it's essential 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 has just begun to piece together the important role they play in our health (and more exciting research is on the horizon). 

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. 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? 

1. 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. 

2. 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. 

3. 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. 

4. It might reduce the incidence of autoimmune diseases.  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. 

5. 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. The study found that when mice with the bacteria Staphylococcus epidermidi were exposed to UV rays, they developed significantly fewer tumors than the mice without it.

Are your products making you sick? 

How is the microbiome compromised and what happens? You're probably familiar with the idea that 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, 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, and accelerated skin aging. 

It's compromised by way of two factors: what you put on our skin, and what you put in your body. 

1. You're using the wrong products. 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 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. Also interesting: 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. 

2. Your gut microbiome is compromised, too. Finally, 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 moodregulating neurotransmitters.