The potential of probiotics and postbiotics in skin care
Probiotics are defined as live microorganisms that, when administered in adequate amounts, confer health benefits to the host. Different to them, postbiotics are inactivated microorganisms or molecules produced and/or secreted after the lysis of bacteria that provide positive effects. Studies show that both probiotics and postbiotics for external use contribute to the prevention and treatment of signs of aging and various skin conditions, with the advantages of being natural, safe and sustainable active ingredients, with lower allergenic potential. However, queries related to the production, regulation and substantiation of claims are still a challenge for probiotics in skincare, opening space for clarifying the use of postbiotics and their consolidation as a viable alternative for cosmetic applications.
In addition to being a physical barrier in organized layers of different cells (1), the skin houses a non-harmful microbial and symbiotic community that is invisible to the naked eye. Thanks to the advances in DNA sequencing methods, it is now possible to analyze microorganisms in their habitat using in vitro culture-independent methods (2) and therefore it is possible to visualize and quantify the microbial population that inhabits the skin. A diversity of more than a 100 species and 1 million microorganisms inhabits each square centimeter of the skin while the skin appendages, sebaceous glands, and hair follicles, contain around 1 billion bacteria (3).
According to Foxman (4), humans have more microbial cells on the skin surface than human cells throughout the body. The set of all these communities by the extension of the skin defines the skin microbiota (5). In fact, microbial genes are not only found in the epidermal region of the skin surface, but also in deeper dermal layers as discovered through DNA metagenomic techniques (6, 7).
As a fetus, the baby has contact with the maternal microorgan ...