Like this article? We’ve got more! Check out the rest of our articles on skincare innovation, skin health, and combatting environmental stressors.
This article was crossposted and reformatted from the original blog post on Apostrophe's website.

Like this article? We’ve got more! Check out the rest of our articles on skincare innovation, skin health, and combatting environmental stressors.
This article was crossposted and reformatted from the original blog post on Apostrophe's website.
Probiotics. Prebiotics. Antibiotics. You may be hearing a lot of buzz around these terms in scientific research communities and from marketing claims in your local skincare aisle. Instead of claiming to eliminate bacteria, many different companies are advocating for improving the bacteria that already colonizes our bodies. But what does the science really say about how these products may help our skin? Apostrophe’s medical director, Dr. Aimee Paik, sat down with Sundaily’s very own co-founder and Chief Scientific Officer, Dr. Emilia Javorsky, to unpack the science around the skin microbiome and bust some marketing myths!
Q: What is a skin microbiome?
Dr. Paik: A microbiome consists of all the microorganisms present in or on the human body. We have talked about the gut microbiome for some time, but now there is much more interest in the skin microbiome. There are trillions of microorganisms in and on our bodies and these microorganisms are estimated to outnumber human cells by a factor of 10. That means there are 10 microbes to one human cell, so it’s a huge part of our makeup. In terms of the skin microbiome, it’s estimated that one billion bacteria inhabit a typical square centimeter of skin (that includes not only the surface of the skin, but also down in hair follicles and sweat glands). I know it gives people a creepy crawly sensation to think they are covered in microbes, but most of them are harmless (i.e., commensal), meaning they neither help us nor hurt us. Some of them are symbiotic, meaning they actually help us, while others are pathogenic, meaning they cause disease.
Dr. Javorsky: That’s a great description! I think the other thing to note when thinking about the microbiome is its diversity. Every microbiome differs from person to person, and it even differs in different areas of our bodies. Areas that tend to be oily with lots of sebaceous glands will have different bacteria compared to moist areas (like the inside of your elbow) or drier areas like your forearm or the front of your leg. It’s really complicated, almost like a whole other organ system, because there’s much variability both between individuals and over the map of our own skin.
Q: Do our microbiomes age with us? Do they change over the course of our lives?
Dr. J: The skin microbiome in general is very new to the research space, unlike the flora in our gut which have been extensively studied, and we’re still only beginning to understand it There’s really interesting work on the “gut-brain-skin axis” which is all about how the microbiomes inside our digestive system can have an impact on our skin via our central nervous system.
Our microbiomes (skin and gut) are dynamic and change throughout our lifetimes. We are first colonized by bacteria when we are born via the mother’s microbiome. How does that change when we go through the stages of life? For the skin microbiome there are well characterized changes during puberty, and also emerging data around how the microbiome continues to evolve throughout adulthood.
The big unknown in this area: do alterations in the microbiome cause skin aging? There is a lot of interest right now, but given the limited data it remains a “chicken or the egg” -type question. Aging involves multiple factors and, in terms of “microbiome’s role,” so far most of the human data is characterizing the changes, not what’s driving them. Does aging change the microbiome because the skin doesn’t hold moisture as well, or do other changes in our skin pH or sweat gland output? What about the different products we use on our skin and how they can affect the environment the bacteria live in? It’s a really interesting area of investigation as to why the microbiome changes as we age. We know that it does, but we’re not 100% sure yet what is driving those changes.
Q: How does the microbiome contribute to skin diseases and what should the typical person be aware of?
Dr. P: “Microbiome” is this trendy new word, but in dermatology we’ve talked about normal skin flora for a long time. We know that microorganisms are part of our skin and that our relationship with them is really complex. For instance, Staphylococcus aureus (or Staph aureus) can be both commensal or pathogenic, meaning it can just live on our skin or in our nose and not cause any problems, or it can cause serious infections of the skin.
The state of the skin also plays a role. There are certain organisms that can live on our skin 