The skin microbiome is often considered a separate organ – and one with great complexity and sophistication. The activity that occurs in this vast ecosystem is essential for our health and wellbeing. We are increasingly aware of how human health correlates with individual, diverse and site-specific microbiomes that need to be protected. For the skincare industry, the traditional approaches that focused on eradicating microbes, or skin bacterial flora, no longer applies. Current research on the complex interplay between the skin microbiota, the barrier function and the immune system indicates that the microbiota has a beneficial role, much like that of the gut microbiome. Understanding what constitutes a healthy and unhealthy (dysbiotic) skin microbiome is essential.1
“The question remains, how do we apply this expanding knowledge to skin treatments or cosmetics approaches?”
In respect of skin microbiome, the research is lagging behind the science of the gut and oral microbiome by more than a decade. The array of factors that impact and change the microbiome composition are vast. Skin conditions are of course one, but also factors such as ageing or the environment alter our microbiome make-up. We are continually discovering these: a US Amway study identified two distinctive Corynebacteria species that could serve as potential targets in anti-ageing skincare.2 One species was associated with older and one with younger participants, replacing one another at middle age (40-49), and the two bacteria did not exist simultaneously. Additionally, the “old” Corynebacterium was associated with wrinkles, skin redness and age spots – the tell-tale signs of ageing.3 Discoveries of this ilk are a catalyst for new thinking and approaches in the skin care industry. The question remains, how do we apply this expanding knowledge to skin treatments or cosmetics approaches?
Three core approaches
Strategies for a more selective modulation of the skin microbiome are on trend. An increasing number of products with substrates (prebiotics), live bacteria (probiotics) and bacterial metabolites (postbiotics) to modulate skin microbiome and promote skin health are brought to market.
As is established, the skin ecosystem is a complex environment with a diverse and individual microbial community and microbes i.e. Staphylococcus, Streptococcus, Micrococcus, Corynebacterium, Propionibacterium. These resident or transient microbes exert a beneficial or pathogenic effect on the skin – or at least have the capacity to do so. So, how can we develop the best technologies to benefit skin health? Among other possible ‘microbiome modulating’ solutions this article focuses on pre-, pro- and post-biotic ingredient approaches. These should be able to optimise, maintain and restore the healthy microbiota of the skin, but what are they and what impact do they have?
Probiotics include various strains of bacteria, e.g. Lactobacillus and Bifidobacterium, that selectively increase the activity and growth of ‘normal’ skin microbes and help produce antimicrobial peptides to support immune stimulation and eliminate pathogens (colonisation resistance). The most known and recognized probiotics are lactobacteries (g. Lactobacillus and Bifidobacterium ). Probiotics can alsobe skin bacteria (eg Actinocateria). The challenges of introducing live bacteria bring up the question of product stability and preservation.
Prebiotics are substrates that serve as a source of nutrition for microbes and induce the growth or activity of beneficial microorganisms by optimising their metabolism, and consequently protecting and nurturing the skin, eg. prebiotic sugars are xylitol and fructooligosaccharides. An example of this is Bioecolia, launched by Solabia. It is a prebiotic, α-glucan oligosaccharide, obtained by enzymatic processing, that claims bio-selectivity and competitive inhibition to avoid dysbiosis. Bioecolia also claims to strengthen the skin natural defences by stimulating the production of antimicrobial peptides.4
Postbiotics are metabolites and/or cell-wall components released by beneficial bacteria e.g. lysates, vitamins and phospholipids, and lactic acid. Working in close collaboration with the probiotics specialist Probi, Sweden, Symrise has developed a specific Lactobacillus strain Lactobacillus plantarum HEAL19 for topical applications. Thanks to a mild heat-treatment to prohibit vitality while maintaining the bacterial structures the technology shows probiotic-like benefits: barrier strengthening, skin soothing, modulation of the cross-talk between skin cells and microbiota. It has been proven clinically to significantly reduce TEWL versus placebo within a week. However, the mild head might lyse the bacteria partially, leading to the first probiotic and postbiotic technology on the market.5
“Unravelling functional relevance of microbiome changes in relation to skin hydration, radiance, redness or itching is in its infancy.”
Regardless of the trend and new product launches, scientists are far from understanding the efficacy of these synergistic ingredients and which combinations are best for healthy skin and chronic skin conditions. A mix of probiotics, prebiotics and postbiotics, such as lysates, seems to help reinforce skin health, function and improve its overall appearance but more research is required. Rebalancing the skin microbiome can help to:
- Enhance the skin’s natural defence systems and ability to respond to environmental aggressors.
- Alleviate dehydration and dryness, including a tight uncomfortable skin feel, reduce triggers of skin sensitization.
- Restore a healthy pH balance to skin surface.
In addition to the cosmetic applications and benefits, there is a growing bank of research illustrating the medical and health benefits of rebalancing the skin microbiome.
Skincare products should, in the least, preserve a healthy skin microbiome – a step-change from approaches in the recent past. Given our limited understanding to date, their effect on the microbiome composition and activity, and non-invasive skin parameters, should be tested in clinical trials to determine the real-life consumer benefit
With the demand for personalized skin care, a number of companies are driving the research field. Recently, L’Oreal Technology Incubator have partnered with uBiome to conduct research on the skin’s bacterial ecosystem and connect consumers with insight on their individual skin microbiomes. L’Oréal is just one example of the key players with a strong focus on scientific innovation and exploration into the skin microbiome, linking it to the skin barrier function, ageing and the immune system. Whilst uBiome reportedly hosts the world’s largest database of human microbiomes, built from at-home microbiome sampling kits, this union will advance scientific research and leverage new technologies for the future of personalized skin care enhancing our grasp of the interplay between bacterial diversity and skin health.6
Microbiome marketing or science?
The strong market pull is the current driver as scientists scramble to apply sound scientific approach to this new trend in skincare. The skin is a complex and individual system of hundreds of species and strains. Unravelling functional relevance of microbiome changes in relation to skin hydration, radiance, redness or itching is in its infancy. There are many extrinsic and intrinsic influencing factors and high inter-individual variability. So much is unknown about the detection and maintenance of a healthy skin microbiome and its functionality; the definitions of a healthy and normal skin microbiome, ‘good/beneficial’ and ‘bad/adverse’ microorganisms and their relevant metabolites are being questioned and understanding advanced. Carefully conducted, multidisciplinary research involving microbiologists and immunologists is called for.