We all know too much sun exposure, tobacco and pollution are bad for our skin.
But the rate at which the skin ages can actually be the bacteria living on it?
It’s a theory scientists are investigating as they study the skin microbiome—the collection of microorganisms that live on the skin’s surface.
Many of us are now familiar with the gut microbiome – the mix of bacteria, viruses and fungi that live in our gut and play an important role in immunity and health.
Now, it seems, the cocktail of bugs living on our skin may be important to skin health — and how fast we age, apparently.
Now, it seems, the cocktail of bugs living on our skin may be important for skin health — and how quickly we age, apparently.
Increasingly, evidence indicates a relationship between the composition of the human skin microbiome and conditions such as psoriasis, acne and dermatitis.
A study published last year in the journal Frontiers in Cellular and Infection Microbiology said: ‘Current knowledge suggests that bacterial, fungal and viral species have under- or over-influence in a number of dermatoses. [skin diseases] Compared to healthy skin.’
Already such research has helped inform treatments for certain conditions, explains dermatologist Dr. Jason Thomson, chief medical officer of the prescription skincare brand, Skin + Me: ‘Many of the effective treatments we use are specific components of the microbiome for certain skin diseases.
‘The antibiotic clindamycin is used to target the bacteria that cause acne. The antiparasitic drug ivermectin is an effective treatment that targets demodex mites in rosacea, and antifungal treatments such as ketoconazole target the Malassezia fungus associated with seborrheic dermatitis,’ he says.
While there is little data on the differences between young and old skin microbiomes, a collaboration between cosmetics giant Chanel’s Paris skincare lab and the Jackson Laboratory, a US research institute, is helping to shed light on the issue.
The scientists analyzed the bacteria in the cheeks of 51 women – a group aged 20 to 26 and an older group, aged 54 to 60 – as well as the quantity and quality of collagen (the protein that thickens the skin).
Not only did younger skin have more moisture and stronger collagen (as expected), but it also had different bacteria.
For example, Cutibacterium acnes, commonly found in oils produced by the skin and associated with acne, was more prevalent in younger people.
Meanwhile, Staphylococcus epidermidis, a bacteria commonly found on the skin that doesn’t cause problems in healthy people but can cause infections in the immunocompromised, was higher in older people than in the elderly in a study published on biorxiv.org.
‘We found many changes in the diversity and types of microbes in aging facial skin,’ said Julia Oh, lead author of the study.
He adds that ‘other studies have shown that the skin microbiome can influence skin barrier repair’.
But are these new discoveries significant? After all, we know that the skin produces less sebum as we age, so it seems natural that the bacteria associated with sebum would decrease as they have less to ‘eat’ on.
It’s also known that collagen decreases with age — but does our skin bacteria play a role?
‘Collagen, elastin and the structures that make them up are much deeper in the skin than the microbiome on the skin’s surface,’ says Dr Catherine Borisiewicz, a dermatologist at Dr David Jack Private Clinic in London.
‘However, we know that these formations can be stimulated by an immune response and so it is possible that working with the microbiome, which we know plays an important role in the skin’s immune system, can have an effect on collagen levels. and elastin.’
Increasingly, evidence points to a link between the composition of the human skin microbiome and conditions such as psoriasis, acne (pictured) and dermatitis.
Dr Gil Westgate, a research scientist at Bradford University’s Center for Skin Sciences, said the research is at an early stage, but broadly speaking, the evidence suggests that it’s the make-up of the skin microbiome rather than the other way around.
‘We know that the environment determines what grows there – in this instance, the most likely explanation is that age changes the skin, which in turn changes the microflora. [i.e. bacteria and other microorganisms].’
However, this is not to say that the microbiome does not play a role in skin aging.
‘One of its roles is its interaction with skin cells and consequently communication between the skin and the immune system,’ says Dr Westgate.
‘It is known that the microflora of the skin helps to train the immune system. If the microflora is altered, this protection may be compromised.
As the immune system declines with age, communication between the skin microflora and the immune system becomes less effective. The result is skin that injures more easily and takes longer to heal,’ she says.
But while it is possible to identify the right microbiome for youthful skin, making permanent changes to a person’s microbiome is not straightforward.
This may involve changing the skin’s environment to encourage the growth of good bacteria – for example, moisturizing daily to relieve dry skin. [studies suggest well-moisturised skin has a healthier microbiome],’ said Dr. Westgate.
This can include using probiotic products, which contain live organisms that increase ‘good’ bacteria — these are now being marketed for acne and eczema, he adds.
Yet ‘although there is some evidence to suggest that you can temporarily change the microbiome by using a topical product, you have to apply it continuously,’ says Dr Thomson.
He points to a study in which researchers took swabs from the skin over a two-year period—results, published in the journal Cell in 2016, suggesting that the skin microbiome is largely stable.
‘This suggests that regardless of our interventions – whether we’re trying to ‘improve’ the microbiome, or worry about damaging it with cleansers or exfoliation – it’s likely to return to our own ‘normal’.’