SKIN MICROBIOME


available in the market, these findings may just be a drop in the ocean. However, they also provide a flavour of what the cosmetic industry could achieve if their goal is to improve the skin properties and coincidentally to enhance the microbiome with currently available products.


What is the effect of the substances that are designed to modulate skin microbiome? There are three major groups of products that are being researched for their usefulness to positively modify the microbiome. These are probiotics, prebiotics, and postbiotics. Probiotics are the live microorganisms that can promote beneficial effects to the skin, prebiotics are nondigestible food ingredients that stimulate the growth or activity of microorganisms, while post- biotics are metabolites or components of the microorganisms.2,28 The application of prebiotics, probiotics, and


postbiotics for the treatment of skin alterations have been a topic of interest in the dermatology field. The data suggest that in some instances, due to gut-skin microbiome axis, sometimes it is enough to supplement microorganisms orally, and certain skin conditions tend to improve.29 Quite a lot of attention has been paid to


exploring topical use of gut microorganisms, especially Lactobacilli and Lactococcus. The intent is to use them as a skin probiotic which is based on in vitro research showing that these bacteria produce bacteriocin, which can help control the growth of pathogenic bacteria, such as S. aureus and C. acnes and reduce the inflammations associated with these microorganisms.29 There are several clinical studies that found


positive topical probiotic or postbiotic effects on skin diseases: ■ Several good candidates to be applied topically for acne treatment that were able to reduce inflammatory lesions: Enterococcus faecalis SL-5, Lactobacillus plantarum30


and


Nitrosomonas eutropha.31 ■ The severity of atopic dermatitis was reduced by transplanting Roseomonas mucosa onto skin,32


using the lysate of Vitreoscilla filiformis (postbiotic)33 and sonicated Steptococcus thermophillus (postbiotic).34 A


successful trial using phage endolysin against S. aureus led the technology which was approved a “drug” for eczema treatment.35 ■ The severity of seborrheic dermatitis was positively modified by improving bacterial diversity using the V. filiformis probiotic36


and


postbiotic.37 The intentional incorporation of


S. epidermidis into the skin microbiome (applied with gel) resulted in improved skin barrier function and maintained skin acid mantle, however, and regretfully there was no microbiome study done to evaluate its changes.38 Given that the majority of the discussed


probiotics and postbiotics are intended for disease treatment, their use as cosmetic treatments might be complicated due to regulatory requirements.


Regulations and limits for cosmetic manufacturers The regulations guiding cosmetics that affect microbiome is complicated in both the US and EU. In the US, the inclusion of probiotics in


cosmetic products is not restricted, although the stability of microorganisms have to be ensured till the products’ expiration date.39


Despite all the


scientific evidence that companies could gather about product effectiveness, it is expected that claims of cosmetic products will not advertise nor publicise any effects or functions on the body/ tissue structure.40


are often advised to significantly “minimise” the observations during clinical trials. For example, reduces the appearance of redness instead of manages or prevents rosecea outbreak.39 EU, legislation is both complex and strict.


According to EU Common Claims Criteria (2013) and Technical Document on Cosmetic Claims (2017), claims on cosmetic products should conform to the following common criteria (from 1 July 2019):41 ■ Legal compliance (follow the law, and don’t claim on something that is legally required anyhow), ■ Truthfulness (do not make false claims), ■ Evidential support (have data to support


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your claims), ■ Honesty (interpret your support data accurately and fairly, and use representative data), ■ Fairness (don’t denigrate others), ■ Informed decision-making (write your claims clearly). A good example of how such a system works


is recently Advertising Standards Authority (ASA) issued ruling regarding Unilever’s claim that Baby Dove wash and lotion could “nourish” a baby’s skin microbiome.42


The claim was


considered misleading and insufficiently substantiated. The more interesting reasons for that were: (i) failure to convince ASA that the “good” bacteria are truly good; (ii) the evidence that the “good” bacteria species increased while the bad ones have remained the same was obtained while studying adults with dry skin and not the babies who are the target consumer; (iii) the study that was done on babies showed no difference in microbiome. This ruling serves as a warning to other


cosmetic manufacturers that more rigorous testing is required for even basic claims such as nourishing microbiome.


Therefore cosmetic manufacturers


So what can be done by cosmetic manufacturers? Due to the lack of research by government bodies, the regulatory agencies may need to rely on available scientific literature that can confuse at best and contradict at worst. As the examples above showed, even such innocent terms as “good” and “bad” microorganisms may get in the way of acceptable claim substantiation: when can a transient microorganism be considered good because it aids the commensal microbiome, although it is not resident to the skin but applied by cosmetic products? Until regulatory bodies decide how much change in microbiome that affects tissue structure and functions are acceptable for cosmetic treatments, the path to microbiome claims will continue to remain a maze without an exit. As it is one of the more difficult challenges we face, is it worth concidering an alternative of choosing a path of over-the- counter-drug similar to suncreens, deodorants, creams for eczema (including the ones with phages), lip balms etc.? Consumers would also appreciate clear, scientifically proven statements with a slightly higher price tag than a cheaper but vague promise.


PC


References 1. Berg G, Rybakova D, Fischer D, Cernava T, Vergès MCC, Charles T, Schloter M. Microbiome definition re-visited: old concepts and new challenges. Microbiome, 2020; 8(1):1-22.


2. Sfriso R, Egert M, Gempeler M, Voegeli R, Campiche R. Revealing the secret life of skin - with the microbiome you never walk alone. Int. J. Cosmet. Sci. 2020; 42:116–126.


3. Grice EA, Segre JA. The skin microbiome. Nat Rev Microbiol. 2011;9(4):244–253.


4. Dréno B, Araviiskaia E, Berardesca E, Gontijo G, Sanchez Viera M, Xiang LF, et al. Microbiome in healthy skin, update for dermatologists. JEADV, 2016;30:2038–2047.


www.personalcaremagazine.com September 2021 PERSONAL CARE


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