Impact of Topical Products on Skin Microbiome Composition: A Four-Week Study on Dexpanthenol-Containing Products 

The skin microbiome, a diverse and dynamic ecosystem of microorganisms, plays a vital role in maintaining skin health and homeostasis. As both intrinsic factors like age, sex, and body site, and extrinsic influences such as pollution and topical products, affect the microbiome, it becomes imperative to evaluate the impact of skincare formulations on this delicate balance. Researchers focused on understanding the effect of dexpanthenol-containing products on the skin microbiome over four weeks. Dexpanthenol, recognized for its skin-barrier enhancement and moisturizing properties, was investigated for its potential to preserve microbial diversity and composition. The research aimed to determine whether carefully formulated topical products could maintain the natural balance of the microbiome without significantly altering it, particularly in subjects with cosmetically dry skin. 

Methods 

Four clinical studies were conducted on European participants with cosmetically dry skin. Microbiome samples were collected from the face and forearm before and after using dexpanthenol-containing products. Microbial richness, Shannon diversity index, and bacterial species distribution were analyzed across various demographics and body sites. 

Key Findings 

  1. Microbial Diversity and Composition
    1. The skin microbiome composition demonstrated stability over the four-week study period. 
    2. No significant changes in microbiome richness or Shannon diversity index were observed at the individual product level. 
    3. A meta-analysis showed variations in microbiome composition influenced by age, sex, and body site. 
  2. Age and Sex-Related Variations
    1. Older individuals (60+ years) exhibited greater microbial richness. 
    2. Significant differences in richness (p = 0.001) and Shannon diversity index (p < 0.001) were noted for facial skin by age and sex. 
    3. On the forearm, Shannon diversity index differences were significant (p < 0.001), but richness variations were not statistically significant (p = 0.063). 
  3. Impact of Ingredients
    1. Ingredients like xanthan gum showed potential benefits for dry skin. 
    2. The presence of xanthan gum increased on the skin surface after using certain products, aligning with its reported enzymatic benefits for keratin hydrolysis. 
  4. Bacterial Species Distribution
    1. Average bacterial counts of prevalent species (Staphylococcus epidermidis, Staphylococcus aureus, Cutibacterium acnes) varied by body site and sex. 
    2. Females exhibited slightly elevated levels of S. aureus, potentially contributing to issues like increased α-toxin production, skin inflammation, and sensitivity. 

Dexpanthenol-containing products demonstrated minimal disruption to the skin microbiome, making them microbiome-friendly for cosmetically dry skin. Researchers highlighted the significance of factors like age, sex, and body site in shaping microbial diversity. While the findings underscore the potential of microbiome-conscious formulations, further research is needed to address limitations such as small sample sizes, uneven demographic representation, and the absence of non-bacterial microbiome components. Future studies should explore diverse populations, long-term microbiome dynamics, and additional biomarkers to better inform skincare product development. 

Link to the study: https://www.mdpi.com/2079-9284/11/6/213