We’ve all heard of gut bacteria, but what about skin bacteria?
The skin microbiome is a new and exciting area of research—and it could change how we look after our skin forever. This article covers what we know about our skin bacteria so far, and how to harness their power for clear, radiant skin.
What is the skin microbiome?
What do we know about the human skin microbiome?
So, can you get bacterial acne?
What about a staph skin infection?
Do gut bacteria affect skin bacteria?
Can you get probiotic skincare?
How to cultivate balanced skin bacteria
Your skin is home to a diverse collection of bacteria, viruses, fungi and even mites . Together, these are known as your ‘skin microbiome’. We used to think that these little critters resided only on your skin surface, but newer research suggests they get down into deeper layers of your skin too . See below:
Wait! Resist the urge to take a shower. You want to keep these little creatures because they play a crucial role in maintaining healthy, glowing skin.
Think of it like this: you’re a castle, and your skin microbiome is an army of soldiers. The castle wall represents the physical barrier of your skin—it does a great job of keeping things out, but sometimes it needs extra support. This is where the soldiers step in. They train the residents of the castle with wily tactics and use their special ammunition to keep the castle safe.
That’s what your skin microbiome does for you. Not only does it defend you against invading pathogens, but it also helps to train your immune system . A strong, balanced microbiome is so important to the health of your skin that when it’s disrupted, it’s associated with conditions such as acne, rosacea, psoriasis and atopic dermatitis .
Like the gut microbiome, we’re only beginning to uncover the secrets of the human skin microbiome. So far we know skin bacteria vary according to the region of the body. We also know that we can influence bacterial populations from both the inside and the outside.
Let’s start at the beginning. As soon as a baby is born, bacteria from its environment start to colonise its skin. The very first bacteria will either come from the mother’s vagina if the baby is born naturally, or from her skin if the baby is born via caesarean [5, 6].
The gut microbiome is usually established by the time a child reaches three years old, but the skin microbiome is more changeable . It undergoes a big shift when the child reaches puberty. This is because certain types of bacteria and fungi feed on skin oil (sebum) so—during the greasy teenage years—these microbes have a feeding frenzy and start to take up more space .
By adulthood, lots of external factors influence skin bacteria. These include:
– Geographical origin
– Drug use
– Exposure to UV light
– Owning a pet
A person’s sex and age play a role too . However, the most significant factor affecting any colony of bacteria is where on the body it’s found. Certain bacteria like dry areas, others prefer a moist environment, and others want nothing more than a nice oily spot.
In a funny way, your body is a microcosm of the earth. Just as you find different creatures in the desert, rainforest and ocean, you’ll discover different species of bacteria in different skin environments. If you’re a visual person, you’ll find this colour-coded diagram from a 2011 research paper brings these differences to life:
(Quick aside: we talk mainly about skin bacteria because that’s what scientists have studied the most. We also know that human papilloma virus hangs out on most people’s skin and that fungi are found all over the body too . Research into skin viruses, fungi and other microbes is ongoing.)
Wherever the bacteria and other microorganisms are found, they need to be in balance. In the right ratios, they help to keep each other in check. If something changes the environment of the skin and enables one type of bacteria to dominate, it has the potential to turn nasty—leading to inflammation, itching, scaling and more .
Most cases of acne have a bacterial component, but not in the way we once thought.
We used to think that a bacterium called Cutibacterium acnes (formerly known as Propionibacterium acnes) was the guilty party. However, newer research suggests that everyone has Cutibacterium acnes on their skin, regardless of whether they suffer from acne or not .
Now it seems that certain types of C. acnes are more inflammatory than others. If the skin-aggravating types are allowed to flourish, they get down into the follicles, start munching on sebum and incite an immune response that leads to angry pimples .
But what enables the problematic C. acnes to flourish? We can’t yet say for sure, but it’s likely that an imbalance in the skin’s overall bacteria enables renegade C. acnes types to run amok .
Another type of acne can be caused by the yeast Malassezia. You can read more about that in Fungal Acne (35+ Studies): The Ultimate Guide.
Staph infection can cause symptoms such as painful red lumps, swelling and blisters. Infection occurs when staphylococcus bacteria—which usually live harmlessly on the skin surface—get down into deeper layers of the skin via a scratch or bite.
But even in the absence of a scratch or bite, it seems some staph bacteria can turn from friend to foe. Again, it’s all about balance. Most people have some pathogenic Staphylococcus aureus (S. aureus) hanging around, but they also have Staphylococcus epidermidis (S. epidermidis), which helps to keep its naughty cousin in check .
Interestingly, people with atopic dermatitis or eczema seem to have more S. aureus . We don’t yet know whether this causes eczema or blooms as a result of it—but, either way, there’s a clear imbalance in the skin microbiome.
That’s right. Do you see a pattern here?
More and more evidence points towards treating your skin well from both the inside and the outside to create the right environment for bacterial balance. To find out how to do this, keep reading.
The gut-skin axis is a hot area of research right now. We know that the gut and the skin are connected, and scientists are working hard to figure out exactly how they communicate.
It’s an odd thought, but your gut and your skin aren’t separate at all. Your skin runs from the outside into your mouth, all the way down into your oesophagus and through your digestive system, until it eventually loops back out at the other end. The environment changes in certain parts of your body and, as you learnt above, that affects which bacteria proliferate—but it’s still one big connected structure.
When you realise that, it makes sense that things that affect your gut bacteria also affect your skin bacteria. Antibiotics change gut bacteria, and they also change skin bacteria . Probiotics can modulate both gut and skin bacteria too .
And yet it appears the connection is even more interesting. Let’s look at a few research findings:
Gut bacteria produce food for skin bacteria. Gut bacteria break down the fibre in your food to create special substances called short-chain fatty acids. These short-chain fatty acids can travel to the skin and affect which types of bacteria grow there .
Gut bacteria can move to your skin. In cases of intestinal hyperpermeability (a.k.a. leaky gut) gut bacteria and their metabolites can slip out of the intestines, ride in the bloodstream and accumulate in the skin—causing irritation .
Gut bacteria modulate the immune system. Your gut bacteria have an intimate relationship with your immune system, which directly influences how immune reactions show up on your skin .
There’s much more to learn. For now, it’s safe to say that looking after your gut bacteria can have a positive effect on your skin bacteria too.
More and more skincare companies are hopping on the skin microbiome bandwagon, adding probiotic-like substances to their formulations to create ‘probiotic skincare’. But do these products work?
Early evidence suggests they have potential. One study found that applying S. epidermidis directly to people’s skin not only increased the population of this natural skin bacteria, but also improved skin moisture levels . Another study found that Streptococcus thermophilus, a bacterium often found in yoghurt, boosted natural levels of ceramides .
Further studies (in petri dishes) have found that applying Lactobacillus bacteria—which, interestingly, are some of the first bacteria to colonise a baby that’s born vaginally—may have a skin-enhancing effect too [20, 21].
And yet there’s a big problem with probiotic skincare: shelf life. Bacteria tend to cause spoilage, which is why most skincare products contain preservatives to keep bacteria at bay. It’s a technical nightmare to try and include live bacteria AND keep a product safe and useable for months.
To overcome this, many skincare companies are stretching the meaning of the term ‘probiotic’. Rather than live, genuine bacteria, they use bacterial ferments (similar to the concept of pasteurised yoghurt) or they kill the bacteria before putting them in the product. They also use lysates, which are fragments of dead bacteria . This is summarised in the handy diagram below:
Other companies use prebiotics instead, which are food for bacteria. Prebiotics tend to be carbohydrate extracts but—as many bacteria that live on the oily regions of your face prefer to eat fats —they may feed the bacteria less effectively than the oily ingredients in the skincare product.
The bottom line? Probiotic skincare is an inexact science. Further research is needed before we can truly manipulate the bacteria on our faces using lotions and potions.
From what we know so far, cultivating balanced skin bacteria is both an inside and an outside job. You can’t control every factor that affects these bacteria but—much like your gut bacteria—you can take steps to help them become a happy and balanced community.
Let’s start on the inside:
Balance your blood sugar. Imbalanced blood sugar can lead to high levels of insulin, which makes your body produce more sebum . More sebum = more oil-loving bacteria, including the acne-associated Cutibacterium acnes. In practice, balancing your blood sugar means eating some protein with every meal or snack, and cutting down on sugar and white-flour products.
Load up on fibre-rich vegetables and fruits. As mentioned above, your gut bacteria feed on fibre, producing special substances that travel to your skin and influence the bacterial populations there. Aim to fill half your plate with vegetables at every meal.
Try probiotics. One animal study found that mice consuming probiotics developed more lustrous fur and a ‘glow of health’! . You’re not a mouse, but studies show that probiotics have beneficial effects on human skin and its bacteria too—from improving moisture levels to helping to combat eczema . Look for a formulation that contains Lactobacilli and Bifidobacteria strains, with 10-50 billion colony forming units (CFUs).
As you can see, much of what you can do to look after your skin bacteria is good for your health as a whole. It’s a win-win.
Moving to the outside:
Take a ‘less is more’ approach. Did you know that molecules from skincare product stay on your skin for weeks, no matter how much you wash? Crucially, they also alter skin bacterial diversity . Reconsider how many products you’re using: are there any you can cut out?
Think twice about harsh treatments. If your skin barrier is damaged, bacteria can travel down to deeper layers of your skin and trigger an inflammatory immune reaction . Treatments such as microdermabrasion and chemical peels may feel like a quick solution, but long-term they run the risk of driving skin-irritating bacterial imbalance.
Protect your pH. The pH of your skin is critical for creating the right environment for good bacteria to flourish . A slightly acidic pH—the natural state of your skin—also kills pathogens . Look for products that have a pH between 4 and 5.5. They’ll often say ‘pH balanced’ on the label.
We still have a lot to learn about the skin microbiome. Here’s what we know so far:
– Your skin is home to bacteria, viruses, fungi, mites and other microorganisms. Together these are known as your ‘skin microbiome’.
– These little critters are important: they keep your skin healthy by protecting you from pathogens and training your immune system.
– Your skin microbiome starts to develop as soon as you’re born. It goes through shifts as you age, but the main thing affecting bacterial populations is whether your skin is dry, moist or oily.
– Skin bacteria can play a role in conditions such as acne and eczema, but scientists are still working out exactly how.
– Your gut bacteria influence your skin bacteria too.
– You can look after your skin bacteria from the inside by balancing your blood sugar, eating fibre-rich fruits and vegetables and taking probiotics.
– You can protect your skin bacteria from the outside by using fewer products, avoiding harsh treatments and maintaining your skin’s acidic pH.
Fiona Lawson is a former national magazine editor turned registered nutritionist and skin specialist. She holds an MSc in Nutritional Medicine and a BANT-registered post-graduate qualification in Nutritional Therapy.