The skin microbiome is having a moment
Do you really need to shower every day or at all? And could showering actually be bad for your skin? Scientists and skin care companies are becoming increasingly aware of the billions of bacteria that live in and on our skin and the potential roles they play there, including eating our natural oils and sweat. Modern hygiene habits may be wiping out these good bugs, leaving us greasier, flakier, and at a greater risk of skin infections than if we just left our skin alone. Consequently, a movement is growing around the idea that people should scale back on the harsh soaps and hot water that have become the norm and let the bacteria just do their thing.
One company in particular, Mother Dirt — the cosmetic arm of AOBiome — is leading the charge. It’s developed a line of products that it claims are friendly to the skin’s microbiome and will let the bugs live in peace. Going one step further, Mother Dirt sells a spray containing a live strain of bacteria to repopulate one of the microbes they say we’ve washed away. The strain — Nitrosomonas eutropha, an ammonia-oxidizing bacterium (AOB) — eats the ammonia in sweat and produces nitric oxide, a molecule that’s important for blood vessel health and combating inflammation. Nitric oxide can also act as a natural antimicrobial, keeping bad bugs like Staphylococcus aureus (the cause of staph infections) at bay.
Nitrosomonas eutropha lives in the dirt, and according to Jennifer Cookson, director of research and product development at Mother Dirt, it existed on the skin of indigenous tribes and on people from “many generations ago before we started our westernized routine of washing every day as well as not interacting with our environment as much as we used to.”
Cookson says that adding back these bacteria and their nitric-oxide-producing abilities helps to normalize the skin, improving both oily and dry skin and potentially helping to treat acne and eczema. The company is currently running clinical trials to test the spray’s efficacy. However, until the results come out, dermatologists and microbiome experts are skeptical.
“It’s not a normal skin bacteria; it’s based in dirt.”
“I haven’t heard of people studying that bacteria on the skin. It’s not a major commensal [symbiotic bacteria],” says Tamia Harris-Tryon, an assistant professor of dermatology at the University of Texas Southwestern Medical Center. “Nitric oxide is known to be antimicrobial, so in that way, it could be beneficial. But there’s nothing that we’re doing in other aspects of dermatology that would make you think that nitric oxide should be this big cure-all.”
“It’s not a normal skin bacteria; it’s based in dirt,” says microbiome expert Tami Lieberman, an assistant professor in the Department of Civil and Environmental Engineering at Massachusetts Institute of Technology. “It doesn’t naturally live on faces, but it may do something beneficial while it’s there.”
Rather than focus on AOBs, microbiome researchers are studying other ways bacteria may influence skin health, for better and for worse. For example, people with eczema have a higher concentration of Staphylococcus aureus, especially during a flareup of the disease, but researchers don’t know whether the microbial shift causes or is a result of the symptoms. People with heavy acne also appear to have a microbial imbalance, with higher amounts of Cutibacterium acnes, which feed on the skin’s oil. Again, though, scientists aren’t sure whether the bacteria cause the acne or simply show up in greater abundance to eat the excess oil historically blamed for pimples.
The argument for trying to maintain a “good” microbiome, either through hygiene habits or probiotics, is that the abundance of beneficial microbes allows less room and nutrients for bad bacteria to take hold. However, instead of optimizing for your microbiome, which is harder to pin down, Harris-Tryon recommends focusing on the health of your skin barrier — the top layer of skin that protects you from the environment and is closely linked to the microbiome.
“If you use harsh soaps and hot water and over-bathe, you’re going to have an impact on your skin barrier,” she says. “If the barrier is disrupted, different microbes grow.”
Sometimes, that does mean bathing less. If you have dry skin, showering once a day, especially using hot water, might be too much; Harris-Tryon says some of her patients bathe just twice a week. Also, avoid using antibacterial or harsh soaps with surfactants (detergents, foaming agents, emulsifiers) that can strip the body’s natural oils and the microbes that live there.
This doesn’t mean you should stop bathing altogether, and it definitely doesn’t mean you should stop washing your hands. “It’s important to bathe,” Harris-Tryon says. “For certain, washing your hands is critical. We know that diseases are spread when you don’t wash your hands because you carry bacteria from person to person.”
Mother Dirt doesn’t say that its bacterial spray should replace bathing (Cookson still showers every day). Hypothetically, though, it could: AOBiome founder and microbe fanatic David Whitlock hasn’t showered in 17 years. “While you can replace a lot of your personal care products potentially with this, I think really the idea is about moderation and being more cognizant of the natural support that your skin offers,” Cookson says.
Despite the probiotic craze, bacteria are not universally beneficial, and even “good” bacteria can cause disease if they get inside the body or wind up where they’re not supposed to be. “If you have broken skin or open wounds and you’re spraying bacteria on it or rubbing dirt on it, I would not recommend that because you’re exposing your body that’s now open to bacteria,” says Harris-Tryon.
Lieberman is more supportive of the premise of using probiotics on the skin, but she says it’s too early to say which bacteria should be added or kept at certain levels to treat which conditions. “I’m optimistic about the future of probiotics for our skin,” she says. “[But] the marketing right now is ahead of the science.”
All Rights Reserved for Dana G Smith