It may not seem intuitive, but to understand some of the new skin care claims, you need to know a bit about the gut microbiome and its role in skin health. TheThe gut and skin play a balancing act between beneficial, neutral, and harmful flora that are interrelated with the innate and adaptive immune systems.1 The skin and gut seem to be intertwined and express several comorbidities.2 In this column, the focus is on the cutaneous microbiome’s role in skin health. To understand the cosmeceutical claims about pre- and probiotics, you first need to familiarize yourself with skin microbiome science. The skin-gut nexus will be discussed in next month’s column, which will address the role of the skin microbiome in skin diseases.
Why is the microbiome such a hot topic?
Genetic sequencing has spurred advances in the study of the microbiome and has provided intriguing clues that the gut and skin microbiome have influences on each other. Sequencing assays that focus on bacterial 16S ribosomal RNA genes have been used by investigators to distinguish and describe the wide variety of resident and transient microorganisms on the skin and elucidate their roles in skin health and disease.1 Genomic sequencing has identified species in the skin and gut that were not found previously by cultivating microbial isolates.3,4 Advances in technologies such as whole-genome shotgun sequencing, metagenomics, and functional metabolomics will further contribute to our understanding of the effects of the skin microbiome on skin health and skin type. Of course, many supplement and cosmeceutical companies have jumped on this bandwagon prematurely and claim that their products increase “good bacteria while diminishing bad bacteria.” While there are interesting data that have emerged, we still cannot say which bacteria are “good” and ‘bad” as far as the skin is concerned – with a few exceptions that we have known all along. For example, Cutibacterium acnes and Staphylococcus aureus still remain in the undesirable category. (P. acnes has been renamed and now is officially referred to as C. acnes.) While it is premature to recommend probiotic– or prebiotic–containing cosmeceuticals, your patients will ask you about them. New studies about rosacea and the microbiome have generated a lot of patient questions in my practice, so I am writing several blogs about how to answer patient questions, which can be found at. I’m also educating consumers on Facebook and Instagram so that they will not be taken advantage of by the too early “pseudoscience.” So now that you have heard that it is too early to recommend pre- and probiotic skin care to target skin issues, let’s look at the science that does exist.
- Microbiome: Microbes that live in a particular environment or biome.
- Microbiota: The collection of living microbes that live in or on an environment. This term includes the microorganisms only and not the characteristics of their environment.
- Prebiotics: A nondigestible food ingredient that promotes the growth of microorganisms in the intestines. These can promote the growth of beneficial or harmful microorganisms. Think of them as a type of “fertilizer” for the microbiome.
- Probiotics: Living microorganisms that can provide beneficial qualities when used orally or topically. What probiotics are not? Microbes naturally found in your body and on your skin; microbes that are no longer alive; fermented foods that contain an unknown amount of bacteria.