A decade ago, I gave my senior expert talk at the University of California, San Francisco, department of dermatology on skin care and brought up the controversial topic that sterile or clean skin is bad. At the time, I initiated the conversation on theToday, I not only preach this message to my patients, but I also practice the “less-is-more” philosophy every day. It is my hope that this brief summary of the skin microbiome and the importance of skin bacteria will affect the development of the next generation of skin care products.
The normal human skin is a microbiome colonized by 10,000-1,000,000 bacteria units/cm2 that prevent the growth of pathogenic organisms and maintain the immunity of the skin. The diversity and type of skin bacteria (that is, Staphylococcus or Propionibacterium acnes), as well as their concentration, varies by person, body location, and environment. Symbiotic with bacteria on the skin are yeasts, such as Malassezia, and parasites, such as Demodex. When the composition and diversity of microorganisms are disrupted, the skin can no longer protect its barrier functions, leading to pathogenic bacterial infections, altered skin pH, decreased production of antimicrobial peptides, and increased inflammation. The microbiome also serves to shield the skin from environmental stressors, such as free radicals, UV radiation, and pollution.
What can lead to disruption of our skin is hygiene. Over-washing; stripping of the skin with lathering cleaner; overexfoliation; long, hot showers; and the use of products with antibacterial properties have increased over the last 50 years, and so has skin disease. The removal of these microorganisms, either by overcleansing or with antibiotic use, disrupts the microflora and leads to pH-imbalanced and inflamed skin. Our microflora contains prebiotics, probiotics, and postbiotics. Prebiotics are the “fertilizer” or “food,” so to speak, that encourages these essential microorganisms to grow; probiotics are the microorganisms themselves; and postbiotics are the chemical byproducts of bacteria, such as antimicrobial peptides and fragments of dead bacterial cells that remain on the skin.
Skin care tailored to our unique microbiome is in its infancy. On the frontier of microflora-rich skin care are organisms like Bifidobacterium longum, which increases the skin’s resistance to temperature and product-related irritation. Streptococcus thermophilus has been shown to increase the production of ceramides in the skin, which could help atopic dermatitis. Lactobacillus paracasei has been shown to inhibit the neuropeptide substance P, which increases inflammation and oil production. Enterococcus faecalis, Streptococcus salivarius, and Lactobacillus plantarum have all been shown to decrease Propionibacterium acnes. Bacillus coagulans and Bifidobacterium breve have been shown to decrease free radicals and protect against UV rays.
Probiotic, prebiotic, and postbiotic skin care, however, does have its challenges. Probiotics are live bacteria, and thus need refrigeration. These products are also not intended for use in anyone who is immunosuppressed or neutropenic. Another complexity in the development of probiotic, prebiotic, and postbiotic skin care is that each person may have a different need in terms of their skin microflora and that microflora is inherently different in different body parts. Furthermore, people with skin inflammation may require a different concentration or population of that flora.
In 2007, the National Institutes of Health initiated the Human Microbiome Project, and in 2016, the White House announced the creation of a new National Microbiome Initiative (NMI). Through this research, the identification and importance of our gut bacteria has led to a vast increase in development and near obsession with probiotic supplements, foods, and drinks (examples include Kombucha tea, kimchi, miso, and Kefir). Although oral consumption of prebiotics and probiotics may prove to be helpful, the skin does have its own unique flora and will benefit from targeted skin care. In the meantime, fostering the skins’s microflora is as important or more important than the replacement of it. My recommendations include using “microflora friendly” products that are lather-free, cream- or oil-based cleansers with acidic pH’s, and moisturizing heavily and consistently. I recommend staying away from antibacterial wipes, antibacterial soaps, and sanitizers.
Fostering this bacterial rich environment will help maintain your skin integrity. Squeaky clean skin is damaged skin.
Dr. Wesley and Dr. Talakoub are cocontributors to this column. Dr. Wesley practices dermatology in Beverly Hills, Calif. Dr. Talakoub is in private practice in McLean, Va. This month’s column is by Dr. Talakoub. Write to them at email@example.com. They had no relevant disclosures.
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