Skin City: The Microbiome

Have you heard people talking about the "microbiome" and wondered what all the fuss is about? Over the last 10-15 years, microbiome research has exploded and revolutionized our understanding of human health and disease. Researchers have uncovered how the body's different microbiomes (that's right, there is more than one "microbiome") influence everything from digestion and immune function to mental health and chronic disease - it's truly fascinating! Before the nerd in me gets too carried away, let's focus on the skin microbiome and why it's important for skin health!

What is the Skin Microbiome?

Imagine your skin as a bustling city. Just like a city has people, buildings and vehicles, your skin has its own tiny residents - bacteria, fungi, viruses. This micro-crew is the skin microbiome. It's a diverse ecosystem that plays a major role in keeping your skin healthy, balanced and glowing. There are also multiple skin microbiomes depending on where on the body we are talking about. The skin microbiome on the face, for instance, will be quite different to the skin microbiome on the scalp or in the armpits! A consistent caveat when discussing this topic is IT'S COMPLICATED! For simplicity, lets think about the face.

Why it's a big deal

1. Barrier Protection: Your skin microbiome acts like an army troop, defending against harmful bacteria and viruses and environmental aggressors. Remember your skin barrier is the outer layer of skin (epidermis) plus the lipids, peptides and immune factors that create an impenetrable shield. A healthy microbiome helps maintain the skin's barrier, keeping out unwanted germs and preventing infections.
2. Balance and Harmony: A well-balanced microbiome keeps your skin's moisture, oil and pH level (level of acidity) in check. When it's out of whack, you might experience dryness, oiliness, acne or irritation.
3. Healing Power: "Good" microbes on your skin can aid in the repair process. They can help soothe inflammation and support skin regeneration, which can be beneficial for healing cuts, scrapes or other skin issues.

The changing landscape

Our microbiome changes throughout our lives. We are born naked (duh - but microbiologically speaking!) and over the first 3 years of life our skin and gut are colonised with increasing diversity of the microbiome. Hormonal changes during puberty shift the skin microbiome, and as we age the sebum (oils) on our skin change which also affects the microbiome and how it functions. Other lifestyle and genetic factors also play a role in changes to your microbiome throughout the lifespan.

Fun Fact: your skin microbiome is YOUR skin microbiome and unique to you!

Just like fingerprints, everyone's skin microbiome is unique. Factors like where you live, what you eat, and even your pets can influence your skin's microbial community. For these reasons there is no true definition of what a "healthy" microbiome looks like because it's different for everyone! What we do know is that balance is key. When things are out of balance and there is an overgrowth of certain bacterias, this can lead to inflammation or skin diseases.

How to keep your skin Microbiome 'happy'?

1. Choose Gentle Products: Opt for skincare products that contain gentle ingredients and are not too harsh on the skin. Look for cleansers and moisturizers with ingredients that support your skin’s natural barrier and provide hydration.
2. Avoid Over-Cleansing: Washing your face too often or with overly aggressive cleansers can strip away the good bacteria and put the balance out. Stick to a routine that’s gentle and unless you wake up oily or sweaty, it's ok to just cleanse once a day in the evening.
3. Moisturise: Keeping your skin hydrated and moisturised helps maintain a healthy microbiome.

Generally speaking, when your skin is healthy, it is really good at re-balancing itself so using small doses of skincare products is unlikely to adversely affect your microbiome. The problems may arise if you use too much or too many products with harsh actives that strip or damage your skin barrier.

Can skincare products improve the skin microbiome?

You might have seen skincare brands marketing products with "microbiome friendly" ingredients, or probiotics, prebiotics or postbiotics to support your skin microbiome, but what do these claims really mean?

Let's do some definitions first -

Probiotics: are live microorganisms, often called "good bacteria".

Prebiotics: are non-digestible compounds that serve as food for the beneficial bacteria on your skin.

Postbiotics: are either inactivated probiotics (dead bacteria) or their DNA. Others say that postbiotics are the metabolites, enzymes, peptides, and other bioactive compounds that probiotics release but this definition is controversial.

With these definitions in mind, you can imagine it's a huge challenge to formulate a topical skincare product with live microorganisms. While there are certain techniques that can be used to overcome these formulation challenges, marketing of creams or serums that mention probiotics should be taken with a healthy dose of skepticism. A more feasible approach is to incorporate pre- or postbiotics into skincare formulations which may provide a benefit to the skin barrier and the microbiome, however the evidence is limited. Dr Kristin Neumann from MyMicrobiome says that there is currently no evidence to support improvement of a healthy microbiome with skincare products (check out The Eco Well podcast episode here). If you have a skin condition, then that might be a different story but you can make the assumption that if you have healthy skin, you have a healthy microbiome and it probably doesnt need improving!

The Takeaway

Like I said - it's complicated!! There is so much still to learn about the skin microbiome. What we do know is that we all have a unique, thriving, dynamic ecosystem living on our skin that's working hard to keep us healthy (kind of icky but also cool!). Doing the regular stuff like keeping your skin clean, hydrated, moisturised and protected will help keep your microbiome happy and healthy. Using products that suit your skin type and being in tune with changes in your skin and modifying your routine accordingly are good ways to support your microbiome and skin health overall, without getting caught up in the 'microbiome marketing'!

As always, if you have significant concerns about your skin it's always best to seek medical advice from your GP or dermatologist.

This is an exciting topic and the research will continue to advance so watch this space!

References:

1. Scharschmidt, T. C., & Fischbach, M. A. (2013). What’s the deal with skin microbiomes? Nature Reviews Microbiology, 11(4), 235-244.
2. Smith, A., Dumbrava, R., Ghori, N. -U. -H., Foster, R., Campbell, J., Duthie, A., Hoyne, G., Rademaker, M., & Bowen, A. C. (2025). An Overview of the Skin Microbiome, the Potential for Pathogen Shift, and Dysbiosis in Common Skin Pathologies. Microorganisms, 13(1), 54. https://doi.org/10.3390/microorganisms13010054

3. Marianne Mychaskiw (January 25, 2023). What's the Deal With Probiotics and Prebiotics in Skincare? Derms Explain the Difference. Byrdie. https://www.byrdie.com/probiotic-vs-prebiotic-skincare-6834767. accessed 3rd January 2025.

4. Yang, Y., Qu, L., Mijakovic, I. et al (2022). Advances in the human skin microbiota and its roles in cutaneous diseases. Microb Cell Fact 21, 176. https://doi.org/10.1186/s12934-022-01901-6
5. Grice, E. A., & Segre, J. A. (2011). The human microbiome: Our second genome. Annual Review of Genomics and Human Genetics, 12, 151-170.
6. Tung, J. L., & Hsu, K. C. (2020). Skin microbiome and its role in inflammation and acne. Journal of Dermatological Science, 99(2), 110-118.