Nearly 10 years ago, the National Institutes of Health launched the Human Microbiome Project, setting off a frenzy of research into how the microbial colonies that live in and on our bodies affect our health. Since that time, more than 650 scientific papers have been published with an additional 289 active clinical studies on the human microbiome currently underway. The findings of these studies are changing the way we view skin disease and skin care.
“There is very solid evidence emerging showing that the microbiome on our skin is very influential when it comes to the overall health of our skin as well as our risk for skin diseases, specifically chronic, recurring skin diseases that have inflammation at their root, such as acne, rosacea, eczema, psoriasis and premature aging,” says Whitney Bowe, MD, medical director of Integrative Dermatology, Aesthetics & Wellness at Advanced Dermatology in New York City, clinical assistant professor of dermatology at the Icahn School of Medicine and author of The Beauty of Dirty Skin.
Healthy skin has a diverse array of bacteria. “The microbiome on the skin is like a rainforest, and the more brightly colored plants that grow in our rainforest, the healthier our skin,” says Dr. Bowe. In patients with chronic skin conditions, this diversity is decreased and there is an overgrowth of pathogenic or harmful bacteria. Historically, treatment has been geared toward destroying bad bacteria, but our growing knowledge of the skin microbiome is piquing new interest in probiotic-based care.
In recent years, researchers have identified several beneficial strains of bacteria that can help reduce flare-ups of chronic skin concerns and protect against premature skin aging. For example, Lactobacillus paracasei, which inhibits skin inflammation, and Streptococcus salivarius, which inhibits the overgrowth of P. acnes, can help to reduce flare-ups in patients with acne and rosacea, says Dr. Bowe.
In addition, certain bacteria provide relief for skin concerns that involve poor skin barrier function. “Probiotics, such as Streptococcus thermophilus, can modify the barrier function by increasing ceramide production,” says Mary-Margaret Kober, MD, of Riverchase Dermatology in Naples, Florida, and co-author, with Dr. Bowe, of “The effect of probiotics on immune regulation, acne, and photoaging” (International Journal of Women’s Dermatology, June 2015).
Bacterial strains Streptococcus thermophilus, Staph hominis and Staph epidermidis “all seem to be very beneficial for patients who struggle with eczema and sensitive skin,” says Dr. Bowe.
How the microbiome affects skin aging is less studied than how the skin’s flora impacts disease, but we are learning more. “The photoaging component is growing,” says Dr. Kober. “The key characteristic of aging skin is that the skin’s pH increases, and this can allow the enzymes that break down collagen to become more reactive. Probiotics can help maintain that optimum skin pH of 5, which suppresses some of those enzymes that break down collagen and elastin and lead to the visible signs of aging.”
We also lose our ability to fight oxidation as we get older because we have a lower number of antioxidants in our skin. “Several beneficial strains have free radical scavenging properties. So they can help fight skin aging that way,” says Dr. Kober.
Currently identified antiaging strains found on the skin include Bacillus coagulans, Lactobacillus plantarum, Lactobacillus paracasei and Bifidobacterium breve. “These are all probiotics that have been shown to have either antioxidant, free radical scavenging properties or they boost ceramide production in the skin, reduce the depth and number of wrinkles in the skin and protect against UV rays,” says Dr. Bowe.
Putting It in a Bottle
As researchers identify specific strains of beneficial bacteria, they are also working to find the best ways to deliver those good bacteria back to the skin. Topically, the three options include products that contain either probiotics, which are the live bacteria; prebiotics, which act as fertilizer or food to encourage the growth of good bacteria; or postbiotics. “Postbiotics are the substances produced and secreted by the live bacteria, such as antimicrobial peptides,” explains Dr. Bowe. “If you grow a bunch of bacterial cells and then separate the cells from the broth surrounding them, that broth is considered a postbiotic. Also in this category are lysed or heat-killed bacteria. What we are learning is that you don’t actually need the live bacteria to have an impact on the health of the skin.”
Thermal water is a prebiotic used by brands including La Roche-Posay and Eau Thermale Avène. “There are certain aspects to thermal water that can make it a prebiotic—things like the mineral content and the pH of the water,” says Dr. Bowe. “The types of molecules in the water can encourage the growth of a very diverse array of bacteria on the skin’s surface.”
Johnson & Johnson presented a poster on the use of colloidal oatmeal as a prebiotic for atopic dermatitis at the 2018 American Academy of Dermatology Conference in San Diego, California. Fang Liu-Walsh, et al, compared Aveeno Eczema Therapy Moisturizing Cream, an emoillent cream containing 1 percent colloidal oatmeal, to a daily moisturizing lotion. The patients using the Aveeno cream showed a significant increase in skin hydration and microbial biodiversity and a decrease in skin pH, while no change was observed with the daily lotion. “Staph epidermidis grows faster than S. aureus and P. acnes in the presence of the oat flour, which also lowers the skin pH,” says Kimberly Capone, PhD, head of Johnson & Johnson’s microbiome platform.
“There are a few probiotic creams available on the market—including Aurelia, Mother Dirt and the Eminence Clear Skin Probiotic Mask—that have several different bacterial strains. But because they are in the cosmeceutical realm, they have not been clinically tested,” says Dr. Kober.
Brands using postbiotics include La Roche-Posay, which uses heat-killed bacteria in its Lipikar Balm AP+ indicated for dry skin, and GlowbioticsMD. “Glowbiotics has some pretty impressive data showing that its postbiotics, which the company calls ‘probiotic-derived bioactives’ or ‘PDB’ do impact the health of the skin in a number of ways. For example, PDB upregulated the expression of multiple collagen molecules and downregulated the production and expression of inflammatory molecules such as interlucan-6 (IL-6) as well as the expression of MMPs, the enzymes that break down collagen,” says Dr. Bowe.
She notes that even products that contain live bacteria require continued use. “Just because you put something on the skin surface doesn’t mean it’s able to replicate and continue to do anything on the skin,” says Dr. Bowe. “Mother Dirt has some interesting data showing that it does have an impact on the skin over time. But you have to continue to use the products every day.”
The Skin-Gut-Brain Axis
While researchers and formulators continue to work toward creating effective topicals based on the science of probiotics, patients needn’t wait to enjoy the benefits. Oral probiotics can also directly affect skin health, thanks to the skin-gut-brain axis. “If you ingest probiotics, you can actually see some of the effects from the oral ingestion at the skin level,” says Dr. Kober. A number of studies, including a December 2012 study published in Photodermatology, Photoimmunology and Photomedicine and a July 2014 study published in Archives of Dermatological Research, showed that an oral probiotic containing Bifidobacterium breve attenuated UV-induced photodamage. “The mechanism of that is not yet fully understood but it shows the far-reaching effects of probiotics on the skin even when taken orally.” says Dr. Kober.
Dermala, a new probiotic-based skincare line developed by researchers at the University of California, San Diego, is offering an acne line that includes an oral probiotic and a prebiotic-based topical to help restore balance to the skin microbiome through both direct contact with the skin and the skin-gut-brain axis. The company is currently developing similar lines for eczema and skin aging.
Dr. Bowe recommends an oral probiotic to all of her patients and also offers instruction on how to develop a microbiome-friendly skincare regimen. “With any kind of skin issue there is nature vs. nurture,” she says. “We can’t do much about our genetics. However, there is a lot about our microbiome that is under our control, and it can be directly impacted by our skincare routines, our hygiene habits, our diet and our stress levels.”
Preserving a Healthy Skin Microbiome
Hygiene and skincare habits that can wreak havoc on the skin microbiome include overexfoliation and extended hot showers. “Extreme temperatures, over-cleansing and over-exfoliating can damage the skin barrier and damage your skin microbiome,” says Dr. Bowe. “To keep your skin’s microbial community healthy and varied, choose a gentle, low-foam, pH-balanced, soap-free cleanser that leaves skin hydrated, not taut.”
She recommends using only one type of exfoliator—a physical scrub or chemical exfoliant—and limiting its use to once or twice a week. “Using a chemical and physical exfoliant can disrupt the skin barrier and create unhealthy shifts in the type of bacteria on the skin,” says Dr. Bowe. “Also, a lot of bacteria require moisture or water to grow and thrive on the skin. So using moisturizers—anything that is gong to trap moisture—is key. You don’t want to let the skin get very dry.”
Dr. Kober recommends moisturizing products that contain ceramides to her patients. “They help maintain the skin barrier and hydration, and that can help protect the skin microbiome,” she says. “Moisturize frequently in the winter months and wear sunscreen. UV light can cause damage and changes to the skin’s composition.”
Returning to the skin-gut-brain axis, dietary habits can also affect skin health. “Things like refined carbohydrates devoid of fiber can encourage the growth of very unhealthy bacteria in the gut, triggering system-wide inflammation, which manifests in the skin,” says Dr. Bowe. “We’re learning that in terms of diet, we need to look at low glycemic index whole or unprocessed foods, such as multigrain breads, quinoa, sweet potatoes, barley and vegetables vs. bagels, cornflakes or white bread.”
While our understanding of the skin microbiome is growing, there is still much to learn. “The microbiome on different parts of our bodies are very different, and each person’s microbial signature is unique. So what might be good for one patient may not be good for another,” says Dr. Bowe. “And we’re still in the process of learning what are the good bacteria that keep skin healthy on the forehead vs. the back or neck, and how that compares to people who have skin concerns.”
When comparing different sites on the body, researchers at Johnson & Johnson discovered that while the moist underarm area has decreased diversity of bacteria, as expected, dry areas such as the legs have more diversity than healthier facial skin. “This suggests that the ‘increasing diversity is good’ theory is too simplistic,” Capone says.
“It could be more like a pendulum where too little diversity is bad, too much diversity is bad, and your middle is healthy skin,” says Menas Kizoulis, head of beauty and global scientific engagement at Johnson & Johnson.
Dr. Bowe envisions a future where physicians can use an individual’s skin microbiome to identify potential concerns and create personalized product regimens. “We aren’t at the point right now where we can swab someone’s skin and say, ‘Here’s your problem, what you need is more prebiotic A, probiotic B and postbiotic C, and you need to start exfoliating three times a week vs. two. But that is in the near future,” she says, adding that as probiotics become a hotter and hotter topic, it is imperative that physicians and skincare specialists do their due diligence in researching product claims.
“Patients are going to come to us with questions, so it’s our job not only to be aware of what probiotics can do but also to push brands selling probiotic-based products to be transparent about the science they have to back their claims,” says Dr. Bowe. “We need to guide our patients to be savvy consumers so they can get the most out of this new knowledge.”
Inga Hansen is the executive editor of MedEsthetics.
Image copyright Getty Images.