Mild skin cleansers strengthen microbiome networks without affecting the skin microbiome

Abstract

Background Human skin, and its associated microbiome, is a delicate ecosystem that faces daily challenges from various external factors such as ultraviolet exposure, pollutants, hygiene habits and cosmetics use. The microbiome can also be affected by internal influences such as diet and stress. Hygiene practices, especially the use of soap and bodywash, play a crucial role in maintaining skin health, hygiene and balance of the microbial ecosystem. Objectives To understand the effects of daily usage of cleansing products on the skin microbiome. Methods Here, we performed 16S rRNA gene-sequencing (V1–V2) analysis of the skin microbiome from participants’ forearms to investigate the effects of regular use of a cleansing product such as a marketed high-glycerine cast melt bar (HGCB) on the skin microbiome. In an additional study, participants' legs were washed with a marketed bodywash with standard petrolatum emulsions, and two uniquely formulated isethionate–taurate-based bodywashes with submicron emulsions containing two different types of occlusives, i.e. petrolatum and plant-derived occlusives. Results The findings from the studies conducted across two distinct geographical locations, involving diverse ethnic populations and various body sites, demonstrate that skin microbiome diversity is preserved following the use of a properly formulated HGCB in addition to all bodywashes containing standard or submicron occlusives. However, single-sample network analysis showed that glycerine-containing cast melt bars and bodywashes containing plant-derived submicron occlusives help to increase the network properties of the skin microbiome, which are reported to be an indicator of healthy skin. Conclusions Our studies demonstrate that the daily use of a HGCB for 4 weeks or daily use of a bodywash containing plant-derived submicron occlusives for 2 weeks has no significant effect on the skin microbiome diversity. The increase in microbial co-occurrence network indicates a resilience to use of such uniquely formulated cleansing products on a regular basis.