Market trends and marketing

The human skin microbiome has recently become a focus of attention for cosmetic industries, with its complexity and variability, opening up several scenarios to consider before launching a new product. Today, understanding the skin microbiota and how to maintain its delicate balance is a fundamental step in understanding the mechanisms responsible for healthy skin appearance. 

The microbiome has become accepted as a major influence on our overall health. This is a positive movement and goes hand in hand with an increasingly health-conscious customer. 

Indeed, cosmetic formulations have greatly expanded their role on the skin: the interactions to be considered have become multiple and complex, not only related to the epidermis, but also to the microbial community present on the skin, which is very different between individuals.

Active ingredients have therefore expanded their efficacy, also taking into account skin micro-organisms, bacteria, fungi and more, including, probably, things that have not yet been considered. The same is true for functional ingredients and even more so for preservatives created to keep cells under control, similar to those of the skin microbiota and which, if not dosed correctly, could affect the balance and health of the skin.

Mintel Global New Products Database market analysis has revealed that since 2017 there has been exponential growth in products launched with microbiome/microbiota claims. This cosmetic revolution has taken hold across the globe: the same comments can be applied to specific analyses on Europe, Asia-Pacific and North America.

In terms of European market figures, articles with microbiota care claims tripled between 2016 and 2019 and doubled again in the last three years. In the Asia-Pacific region, the number of products launched for this purpose increased tenfold.

Meanwhile, in the North American market, finished products targeting microbiota wellness doubled in 2018 compared to the previous year and have been on an upward trend in the four years since.

More and more cosmetics, from oral care to skin care, are targeting the microbiome and are marketed to contain probiotic, prebiotic or postbiotic ingredients. It is also added to a cosmetic product to achieve a cosmetic benefit at the site of application, either directly or through an effect on the existing microbiota.

In addition, it should be noted that some microbiome-related cosmetics do not contain probiotic or prebiotic ingredients. Instead, they are formulated by omitting ingredients that are thought to harm the microbiome and are marketed as microbiome-friendly. These may claim to be free of specific ingredients, such as preservatives or sodium lauryl sulphate (SLS), or generally be formulated as mild and gentle to the skin.

Dermal microbial biodiversity is essential for the proper healthy functioning of the skin. Alterations observed in the dermal microbiome following cosmetic application include changes in skin pH, moisture and barrier function ( Wallen-Russell, 2019 ). 

As scientific evidence suggests that cosmetic products with synthetic ingredients can damage the skin microbiome, the marketing of "microbiome friendly" or "probiotic" cosmetics has emerged.

This growth of the probiotic cosmetic market has resulted in false label claims and may provide misinformation about the use of the term "probiotic" ( Puebla-Barragan & Reid, 2021 ). 

Many labels claim to "balance the skin microbiome, improve the skin barrier and improve overall skin appearance", but there is a lack of scientific evidence to support these "health improvement" claims (Puebla-Barragan & Reid, 2021).

The FDA regulates oral probiotics and similar products ( Venugopalan et al., 2010 ). There is no FDA guidance for claims, but the FDA is aware of the growing problems associated with these "probiotic" claims on cosmetic products, including the fact that most products labelled "probiotic" actually contain postbiotics, which are waste products of live bacteria ( FDA 2019 ). 

The lack of regulatory oversight in this area is not limited to the US, but is increasingly recognised as a global concern.

The International Cooperation on Cosmetic Regulation (ICCR) is made up of regulatory bodies from around the world and meets annually to discuss cosmetics issues. The ICCR focuses on "assessing the safety, quality and regulation of cosmetic products targeting the human skin microbiome" (ICCR, 2022).

Based on input from member states, the ICCR developed harmonised terminology and definitions related to cosmetics and biotics, which are categorised into viable ingredients, non-viable ingredients and other terms.

With regard to "microbiome friendly" or "microbiome gentle" claims in particular, the ICCR stipulates that these are not formal definitions, but act to facilitate the categorisation of cosmetics on the market.

• Viable probiotic: viable microorganisms (live or dormant) added to a cosmetic product to achieve a cosmetic benefit at the application site, either directly or through an effect on the existing microbiota.
• Non-viable probiotic: Non-viable ingredients that are added to a cosmetic product with the intention of being actively used as nutrients by the microbiota at the application site to achieve a cosmetic benefit.
• Non-viable postbiotic: Non-viable ingredients composed of inactivated micro-organisms and/or soluble factors (metabolic products or by-products) released by living or inactivated micro-organisms, added to a cosmetic product to achieve a cosmetic benefit at the application site, either directly or through an effect on the existing microbiota.
• Other: not included in the subgroups of prebiotics, postbiotics and probiotics.

In conclusion, with the increasing diversity and ambiguity of label claims about the health benefits of cosmetic products, better scientific support is needed to verify such claims. 

However, the lack of US and global regulations specific to cosmetics leaves room for false claims and the spread of misinformation. 

ICCR intends to address the gaps in global regulations through voluntary participation in its annual meeting and its development of consistent terminology for the industry. 

Despite this progress, regulatory guidance and oversight remains lacking at national and international levels, leaving consumers in the dark regarding the meaning of microbial claims on their cosmetics.

Regulatory framework for cosmetic products

In addition, there is a lack of regulation for microbiome cosmetics. So-called pre-, pro- and post-biotics are popular ingredients and play an increasingly important role in the personal care industry. They are used to formulate cosmetics and make the customer assume that the product nourishes and enriches the skin's microbiome.  These ingredients are well known in the food industry, but they are not regulated and their definitions in the cosmetics field are missing. Therefore, we have to rely on the definitions found in the food industry. 

The definition of probiotics is 'live micro-organisms that, when administered in adequate amounts, confer a health benefit to the host'.  This is not fully transferable to cosmetics.

In terms of regulation, there are some challenges for live probiotics in cosmetics. Probiotics are not covered by cosmetic regulations and it is still unclear whether this type of ingredient should be classified as a cosmetic ingredient.

Products containing live probiotics must be safe, must not be contaminated with pathogenic microbes and probiotic strains must be distinguishable from undesirable contaminations. In addition to that, the strains used must have a safety profile, which demonstrates the non-toxicity or potential for toxicity of the strain on the skin.

The Food and Drug Administration (FDA) and Canada have expressed some concerns related to this type of cosmetics, specifically with the efficacy, safety and quality of these products. There are still some outstanding questions raised, such as whether probiotics are still alive in cosmetics in the presence of preservatives or whether they affect the quality and safety of the product.

The products that contain probióticos alive have to be safe, do not have to be contaminated with pathogenic microbes and the strains of probióticos have to distinguish of pollutions no wished. Besides that, the strains used have to have a profile of security, that show the no toxicity or the potential of toxicity of the strain in the skin.

The Food and Drug Administration (FDA) and Canada have expressed some worries related with this type of cosmetics, specifically with the efficiency, security and quality of these products. Still there are some pending questions posed, as if the probióticos still are alive in the cosmetics in presence of preservatives or if they affect to the quality and the security of the product.

The definition of cosmetic product and substance/mixture they contain makes no reference to the terms "viable" or "non-viable", so it is unclear whether prebiotics, probiotics and others fall under this definition.

There is regulatory uncertainty as these "ingredients" are neither explicitly prohibited nor permitted.

Cosmetic products must comply with imposed microbiological limits. Depending on the market where the product is available, the use of probiotics may not be an option (as they are considered "live or dormant" microorganisms) or must comply with regional microbiological limits.

In the US, any topical product containing live or latent microorganisms beyond the acceptable limits listed in the Bacteriological Analytical Manual (BAM) is considered adulterated.

In Canada, companies must follow the limits and methods described in the International Organization for Standardization (ISO) Cosmetics Standard - Microbiology - Microbiological limits, ISO 17516:2014.

In South Korea, the use of live microorganisms in cosmetic products is generally not allowed.

In Japan, "cosmetic ingredients, including impurities contained therein, must not contain anything that could cause infection or otherwise make the use of the cosmetic a potential health hazard".

In the European Union, the safety of a cosmetic product must be demonstrated and data on the microbiological quality must be included in the Cosmetic Product Information Report (CPSR), which is part of the Product Information File (PIF). The total count of mesophilic aerobic micro-organisms (bacteria, yeasts and moulds) and the absence of specific micro-organisms (Candida albicans, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli) must be included.

From another perspective, if a cosmetic product mentions that it has pharmaceutical or medicinal activities, it will fall outside the definition of a cosmetic product established by the European Cosmetic Regulation. Claims such as "microbiome friendly" are generally included in this definition. Therapeutic claims (e.g. to prevent or treat disease) are not allowed on cosmetics.

All cosmetic and personal care products must be proven safe for the consumer, under normal and foreseeable conditions of use, and cosmetic claims must be supported and properly substantiated. However, some claims may be difficult or too complex to verify or substantiate (e.g. claims of efficacy on skin microflora).

In summary, can probiotics, prebiotics and postbiotics be considered as cosmetic ingredients, will they interfere with microbiological limits set by regulators, and do cosmetics containing these ingredients fall within the definition of the EU Cosmetics Regulation or should they be considered as bordeline products? Many questions remain to be answered and a case-by-case assessment is generally recommended.

Other regulated markets may set different cosmetic requirements that may differ in terms of microbiological product quality standards.

Claims

The cosmetics industry is using the microbiome trend for new claims, flooding the market with products promising healthier skin. In many cases, marketing gets ahead of the science and the claims are not scientifically backed up.  In recent years, some well-known beauty brands have had to retract their claims due to lack of substantiation.  The reason for this is that the microbiome is not as easy to measure as other parameters in cosmetics, e.g. wrinkles, pore size or hydration. 

Claims that products improve the skin microbiome are innovative claims that would require a high level of evidence to substantiate.  This is because the skin microbiome is very complex, with many layers, and microbes are detected in the dermis, adipose tissue, follicle and epidermis.

A product claiming to balance the skin microbiome should have studies that indicate in many subjects, preferably hundreds, how a given product changes the various layers of microbiota in such a way as to restore and maintain it to what is considered healthy for all. Since it seems highly unlikely that such studies have been conducted for most products, no claims should be made about the balance of the skin microbiome. 

Another regulatory debate is whether microbiome-focused products are "cosmetics" or borderline medicines. Indeed, it has been pointed out by several authorities, in particular the FDA, that some products targeting the skin microbiome refer to activities of a medicinal or pharmaceutical nature. Such product presentations clearly fall outside article 2 of the EU Cosmetics Regulation 1223/2009.

The affirmations on the improvement of the microbioma of the skin in a healthy skin require intensive clinical studies in a very specific group of people during a period of determinate time. These are intensive in time and money and offer information only on a small and very specific group of people in a determinate geographic region.

There is no global standard healthy microbiome, so it is almost impossible to assess whether a product can change everyone's human skin microbiome in a positive way. 

On top of that, the microbiome is affected by many factors, such as genetics, diet, environment, lifestyle and even pet ownership. Therefore, the influence of a single product is only one of many facets. Any therapeutic claim that implies that a product modifies bodily functions or prevents or treats disease is not allowed if the product is considered a "cosmetic". Regulatory inspectors, in particular Health Canada, have been assessing on a case-by-case basis whether products meet the cosmetic definition and have noted non-compliance in microbiome-focused products marketed for skin conditions such as atopic dermatitis, eczema, psoriasis and even injured skin.

In recent years, the development of next-generation sequencing has revolutionised research on the human skin microbiome. This innovative approach is largely based on two main techniques: amplicon sequencing and metagenomics of different bacterial species, and allows us to identify the composition of the bacterial community that settles on the skin at the genus level and sometimes at the species level. 

Metagenomics, for example, uses the whole genome shotgun approach to fragment and sequence the entire DNA of a microbiome sample and should allow the identification of microbes down to the strain level, but with rather high costs and much more data. 

Therefore, companies seeking to manufacture cosmetics focused on the skin microbiome must be careful with product claims. While microbiome or pH balanced would be acceptable, as would any other cosmetic claim, any reference to the treatment or prevention of adverse conditions such as eczema or acne would be construed as a therapeutic claim. Companies marketing cosmetics with therapeutic claims are prosecuted for marketing unauthorised medicines and may be required to withdraw the product from the market. Additional penalties, including imprisonment, may be incurred.

Key considerations to ensure that a product is positioned as a "cosmetic" would be to include a prominent cosmetic function such as "moisturising" or "cleansing" on the label. Additional microbiome claims can be included depending on the type of claim, i.e. "microbiome friendly", or if it supports the cosmetic benefit, "keeps skin in good condition". We should note that a product that treats acne and eczema or repairs damaged skin would not fit the definition of cosmetic even as a secondary claim.

As a final consideration, it is important that all consumer products are tested and determined to be safe for the user, and that all efficacy claims are substantiated. Therefore, relevant scientific data is needed to demonstrate safety and product claims.

In the UK, the advertising authority is quite strict, so claims made about advertising materials, broadcast or otherwise (and online), require a robust dossier. The same principles will apply in other countries around the world. As such, few claims related to the skin microbiome are likely to be made because of the challenges in substantiating them.

This complicates the entire discovery process of initially identifying the microbes of interest and finding ways to influence them or the microbiome as a whole, let alone proving the safety or efficacy of a product. Therefore, in general, efficacy claims about skin microflora are difficult to make if the company wants to go beyond a mere claim that it is friendly to the microbiome or contains pre-, pro- or post-biotics.

This complicates all the process of discovery to identify initially the microbes of interest and find forms to influence in them or in the microbioma in his group; much less test the security or efficiency of a product. Therefore, in general, the affirmations of efficiency on the microflora of the skin are difficult to do if the company wants to go further of a mere affirmation that it is amicable with the microbioma or contains pre, pro or posbióticos.

Conclusion

The microbiota has always been there, even before we realised it existed. The interaction with cosmetics has always been there too, but it was also unknown.

Product safety for the skin, extended to safety for the microbiota in terms of interaction and knowledge of the effects that the formula can bring, means that products can be even more effective and safe, generating new targets for the cosmetics of the future.

The most classical preservatives traditionally used in cosmetics are broad-spectrum biocidal ingredients. There are very few conclusive studies on the effect of preservatives on the skin microbiome, it is anticipated that stronger broad spectrum biocides may have a greater impact on the skin's natural flora.

This means that, on the one hand, we would like to inactivate organisms that accidentally enter the product, and on the other hand, we prefer to maintain healthy, normal skin flora. Regulatory pressure, and sometimes negative pressure on certain chemicals, has limited the palette of preservatives and ingredients for product safety.

While few marketers would call for more regulation, the trend for microbiome-focused skin care continues to grow. And science is accelerating development in this area, providing exciting new developments for the future of personal care. For example, ongoing research is uncovering the role of the microbiome in skin conditions such as psoriasis and identifying ways to provide potential treatment. 

When looking at cosmetics from the perspective of the microbiome, we need a paradigm shift. Instead of looking for the most effective active ingredient, we need to look for low activity in the microbiome, given the background that any interference is potentially harmful.

As we move forward, it will become increasingly important for companies to understand the legal obligations and implications of their microbiome-compatible pre-, pro- and post-microbiotic products in the consumer market. Both companies and regulators will also need to understand how to adapt testing, regulatory and marketing standards for these products to ensure product safety and quality in this emerging space.

The human skin microbiome has recently become a focus of attention for the cosmetic industries. Improving our understanding of host-microbial interactions and how to maintain their delicate balance is essential for the development of new cosmetic formulations.

An integrated approach aims to support the analysis of microbiome sequencing data through the use of biophysical skin measurements. Currently, there is no standardised methodology to monitor the effects of microbiota status before and after active substance application and this will be a major future challenge.

In addition, analysis of the skin microbiome is very complex because our microbiota varies greatly between different locations on the body, so different key species must be considered for each, e.g. face, body, scalp, vulva, mouth or nose.