In Antoine de Saint-Exupery’s tender children’s tale The Little Prince, the titular young prince encounters a friendly fox who tells him, insightfully, “What is essential is invisible to the eye.” Like the rest of the book, the remark is a thematic metaphor about life, love, and the absurdity of being an adult. It is not a reference to the crucial importance of the skin’s invisible microbiome — the billions of unseeable microorganisms that live on its physical barrier — but it certainly could be, taken out of context.
If just looking at the word microbiome makes your eyes roll into the back of your head, here’s a simpler way of putting it: It's germs. “The microbiome is the natural colonization of bacteria that's found on the skin,” explains dermatologist Rachel Nazarian, MD. It’s all the stuff that lives on your body that isn’t you, a kind of ecosystem made up of bacteria, fungi, viruses, and the occasional mite.
Until recently, clinical research into skin health has focused primarily on the skin’s moisture barrier, and how important pH balance and proper hydration are to protecting against inflammation and conditions associated with it. Turns out, though, that it’s not just the skin’s exterior moisture levels that matter; changes in pH balance also throw off the composition of the microbes living on the skin, in symbiosis with the physical barrier. Over-washing, harsh cleansers, using the wrong products for your skin type: Dr. Nazarian cites these common mistakes as surefire ways to mess with the microbiome. (And she’s particularly wary of “home remedies” or “Pinterest-type” skin-care tips, which she calls “extremely risky.”)
“When people complain that their skin is too red, too dry, too itchy, too flaky, too oily, too… anything, it’s potentially because the ideal balance of the skin is off,” Dr. Nazarian explains, “and the pH has shifted, creating a cascade of inflammatory factors and unevenness in the natural flora.” Flora: You’ll see that word again. It’s a pretty term for the mixture of microorganisms that make up the microbiome. Once an afterthought, the skin’s flora has now emerged as an equally important piece of the healthy-skin puzzle.
But the goal is not to destroy certain “bad” bacteria — like P. acnes and S. aureus (which are associated with acne and atopic eczema, respectively) — and replace them with “good” bacteria by reaching for every probiotic serum and tub of unpasteurized yogurt you can get your hands on. Rather, it's bacterial diversity, and it’s a healthy balance of all the microbes — yes, even the ones with a bad reputation.
The case for this diversity is strong: A 2016 review published in Nature found that acne patients often suffered from a reduction in microbe variations, with “overpopulation” of one or another, and that the diversity increased as the wounds healed. In another study from 2013, scientists determined that high diversity was typical of “normal” skin, whereas dermatitis and psoriasis displayed distinctly different bacterial populations. Just last month, a biotech company seeking to further its work in using the microbiome for new dermatological treatments received $2.9 million in Series A grant funding. French skin-care brand La Roche-Posay has been instrumental in conducting research into how bacterial diversity can benefit skin (and it's since developed the Toleriane line, which incorporates prebiotics as “food for bacteria,” based on the brand's findings).
There have been plenty of innovations in the past that promised to revolutionize the skin-care industry — handheld LED devices, serums laced with CBD oil, hydrogen water — but if there’s any one discovery of the past decade that will actually change the way we think about taking care of our skin in the long-term, it’s the microbiome. Because the research is relatively new, skin care engineered specifically to work in conjunction with the skin’s flora is still a fledgling category. Along with La Roche-Posay, Mother Dirt has been at the forefront of microbiome-friendly skin care: The AO+ Mist features a patented variety of live “ammonia-oxidizing bacteria” that works to restore the skin’s natural balance without the aid of topical moisturizers. Cutting-edge brands like Tula, Crude, and Biossance all offer formulas that get their skin-strengthening power from bacteria — and many, many more are sure to follow.
The only drawback of the new research is that it’s brought back to the surface the one thing we’d actually hoped to block out from science class: the fact that tiny eight-legged creatures will always be living on our skin. Sometimes it's just better to forget, especially where arthropods are concerned.