Bacteria: The very thought of it might make your skin crawl. But what if, instead of crawling, your skin actually benefited from bacteria? Scientists believe that healthy bacteria play defense for our skin (the body’s biggest organ) and beauty companies are now introducing probiotic products that either promise not to strip the dermis (our skin’s middle layer) of these aid-abiding microbes or reintroduce them if they’ve been cleansed away. Here, we take a deep dive into “healthy” bacteria and its role in skin.
First things first: What are healthy bacteria?
If you were to put a sliver of skin under a microscope, you’d see a ton of activity. That’s because the microbial communities that live in our skin are the most diverse of the human body — and rightfully so! After all, our skin constantly comes into contact with the outside world, making it an apt environment for diverse bacterial communities. Scientists believe that commensal (aka harmonious) skin bacteria service the skin in two ways: They protect us from pathogenic invaders (the infection-causing bacteria and microorganisms) and help balance our immune system.
Despite our skin being prime real estate for diverse microbial communities, three distinct skin microbiomes stand out:
+ Propionibacterium (including acne-causing P. acnes) live in oily places on the head, neck, chest and back.
+ Corynebacterium hang out in the moist areas — like your elbow creases or between the toes.
+ Staphylococcus, in particular, S. epidermidis, are found in dry, broad, flat areas like our legs or forearms.
How does healthy bacteria benefit the skin?
As we mentioned, these healthy bacteria strains stop pathogens from making their way into our skin’s ecosystem. Plus, they help the immune system balance between protection and inflammation. But let’s dive a little deeper.
Even though we associate P. acnes with acne, the strains found on healthy skin actually carry genes for thiopeptides, antimicrobial compounds that inhibit the growth of gram-positives species. Say what?! Translation: These healthy strains of P. acnes actually kill off other bacteria that are harmful to skin!
Then we have S. epidermidis, which is purported to help with immunity because it secretes lipoteichoic acid (LTA), which prevents inflammatory cytokine release from keratinocytes of human skin. A study in Science Magazine showed that the topical application of S. epidermidis to skin also altered T-cell function to boost host immunity — in effect, making the immune system of the skin capable of controlling infection. In fact, topical application of S. epidermidis has also been proven to wipe out Staphylococcus aureus, which plays a role in eczema.
How do we get this “healthy” bacteria to work for us?
Well, the science isn’t there quite yet. Because some microbes secrete protective antimicrobials and others are associated with disease, the balance is a delicate one — and often a very personalized one. That’s because each individual’s skin landscape is quite different and may need a bespoke approach rather than a blanket one. In other words: A spray bottle containing one microbe to replenish populations of beneficial skin bacteria may not work for all people. Although some skin probiotics currently exist on the market, none are regulated by the FDA. Further, scientists have a few worries, mainly that the wearer may transfer the topical probiotics to other people (or just other parts of her own body) and that could be disruptive to all involved. If the “healthy” bacteria infiltrate a scratch, then what? The research isn’t there yet.
On the flip side, products that are too harsh and strip the skin of healthy bacteria are definitely ones to avoid. Make sure you’re picking products that are gentle and appropriate for your skin type — the same way you should remember why having oily skin is actually a blessing in disguise!
The jury’s still out on skin probiotics — but possibly not for long.
What scientists agree on: Healthy bacteria is an exciting field for skin, and once this microbiome is better understood, the hope is a variety of dermatologic conditions will be addressed through various treatments, including cosmetic probiotics. But as it stands, more research needs to be conducted, not just to learn how microbial ecosystems work on healthy skin and change during illness, but how probiotic products could safely be used to our skin’s benefit. Because, ultimately, safety trumps all else, especially where our skin is concerned.