TESTING 45
Higher pH values at certain body sites like the axilla or the interdigital areas promote the colonisation of certain odour- producing or harmful bacteria and fungi.28, 29 In particular, atopic dermatitis is often linked to increased pH-values and at the same time a different composition of the bacterial associations with an increased presence of Staphylococcus aureus.27
Skin
pH measurement can show whether a shift of the pH value could be obtained by the product application. There are also other measurement parameters that can be used to show a positive effect on skin health.
Conclusion Research on the skin microbiome is a fascinating and trendy topic and will probably evolve further. However, despite the intense research, the microbiome shows huge inter- and intra-individual variation and there has been until now no scientific consensus on its perfect composition. An aspect that still needs more research
effort is the influence of cosmetic products on the resident microbiome. What is happening in the microbiome realm when applying oily formulations on skin areas that by nature do not have high sebum production and feature an adapted healthy microbiome? How can we ensure that added microorganisms will survive in the microbial communities on the skin surface? And might it be possible that the well- meant application of probiotic products might have an adverse effect on the skin microbiome, destroying the adapted balance by adding more species of certain bacteria?
The findings that the skin microbiome is essential for skin health pose a challenge to cosmetic industry to develop new products that not only consider traditional skin types such as oily or dry but to widen their understanding of skin types to certain microbiome types.
Since the claim behind using
formulations modifying, enhancing or feeding the microbiome, is the improvement of skin health and especially the strengthening of the skin barrier function, traditional biophysical testing methods and imaging are well-suited to substantiate health-related claims of such products.
PC
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Figure 9: pH-changes may influence microbial association. Their measurement can give valuable information on the efficacy of products.
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