A forest is a complex ecosystem with lots of organisms living in a delicate balance with each other. There is a food chain, and animals and plants depend on each other for things like pollination and shelter. Like that, the skin on your face, and on your entire body for that matter, is a complex ecosystem with all sorts of bacteria, fungi, and viruses (and mites!) living together in balance with each other, just on a smaller scale than a forest. You can’t get rid of these tiny organisms just by showering, and you wouldn’t want to get rid of most of them, either! They naturally belong on your skin. Together, the microscopic things living on your skin are a community called your skin microbiome and you need it. The microbiome can protect your skin. For example, some good bacteria can crowd out bad bacteria or make your skin inhospitable to bad bacteria¹ . And some good viruses can naturally keep the bacterial population on your skin in balance². Early in life, the skin microbiome trains the immune system to let it live on your skin without causing an immune reaction and inflammation³. So, you need your skin microbiome; it works alongside your immune system so that you can achieve optimal health! But your skin microbiome isn’t just one big stable ecosystem, it is complex and changes depending on the conditions.

Just like Earth’s forests, your skin microbiome is different in different places on your body. Forests change across Earth: in the far north there are boreal forests filled with pine and fir trees, farther south there are deciduous and coniferous temperate forests with all sorts of trees like oak trees and maple trees, and near the equator, there are tropical forests with lots of wild species like mangrove and palm trees. Like that, your skin microbiome also changes across your body. Mary J. Marples, a skin microbiologist, described it this way:

“The skin is an ecosystem, with a microscopic flora and fauna and diverse ecological niches: the desert of the forearm, the cool woods of the scalp and the tropical forest of the arm pit.”

What Marples is essentially saying is that, for example, the microbiome on your face is different from the microbiome on the rest of your skin in a few ways⁵. Your face microbiome has adapted to the combination of the oily sebum that facial sebaceous glands produce and the dryness of being completely exposed to the air all the time. The sebum allows bacteria like Cutibacterium and fungi like Malassezia to grow on your skin alongside Staphylococcus and Micrococcus bacteria that can grow well on most of your skin. Sometimes, microscopic Demodex mites are part of the face’s skin microbiome, too, where they can eat sebum, bacteria, and even skin cells. If you have a balanced microbiome, all is normal and kept under control! Problems arise when elements are out of balance. That’s when you might get breakouts and blemishes, redness, inflammation, and discoloration.

And one person’s skin microbiome can be different from another person’s skin microbiome. If your face has a different amount of oil (sebum) or hydration than someone else’s face, then your skin microbiome is probably different, too⁶. This difference in skin microbiome partly explains variations in skin appearance amongst people. Researchers are continually discovering new associations between the skin microbiome and skin health and appearance, like those mentioned above, as well as uneven tone and texture⁷⁻⁹. It’s becoming clear that balancing the skin microbiome can improve skin health and appearance, contributing to your overall wellness.

So the next time you look at your skin, remember that your skin has an invisible thriving ecosystem of living organisms called a microbiome, like a forest. Taking care of your skin includes tending to your skin microbiome so that it stays balanced. If you can keep your microbiome balanced, then your skin will look and feel healthier, and you’ll gain the confidence that your self-care routine is built on cutting-edge science.

Citations

1. O’Neill, Alan M., et al. "Identification of a Human Skin Commensal Bacterium that Selectively Kills Cutibacterium acnes." Journal of Investigative Dermatology (2020).
2. Hannigan, Geoffrey D., et al. "The human skin double-stranded DNA virome: topographical and temporal diversity, genetic enrichment, and dynamic associations with the host microbiome." MBio 6.5 (2015): e01578-15.
3. Scharschmidt, Tiffany C. "Establishing tolerance to commensal skin bacteria: timing is everything." Dermatologic clinics 35.1 (2017): 1-9.
4. Marples, Mary J. "Life on the human skin." Scientific American 220.1 (1969): 108-115.
5. Grice, Elizabeth A., et al. "Topographical and temporal diversity of the human skin microbiome." Science 324.5931 (2009): 1190-1192.
6. Mukherjee, Souvik, et al. "Sebum and hydration levels in specific regions of human face significantly predict the nature and diversity of facial skin microbiome." Scientific reports 6 (2016): 36062.
7. Quan, Cheng, et al. "Psoriatic lesions are characterized by higher bacterial load and imbalance between Cutibacterium and Corynebacterium." Journal of the American Academy of Dermatology (2019).
8. Marrs, T., and C. Flohr. "The role of skin and gut microbiota in the development of atopic eczema." British Journal of Dermatology 175 (2016): 13-18.
9. Barnard, Emma, et al. "Strains of the Propionibacterium acnes type III lineage are associated with the skin condition progressive macular hypomelanosis." Scientific reports 6.1 (2016): 1-9.