Changes in the Diversity of Human Skin Microbiota to Cosmetic Serum Containing Prebiotics: Results from a Randomized Controlled Trial.

Prebiotic treatment may rebalance the skin microbiota by regulating the growth of harmful and beneficial microorganisms. In this randomized, double-blind, placebo-controlled clinical trial (N = 60), we evaluated the effects of a cosmetic serum containing galacto-oligosaccharides (GOS) on the balance of the skin microbiota by measuring various skin parameters. The skin water-holding capacity between the control (ND) and experimental (NF) groups was significantly different after 8 weeks of serum treatment (p < 0.05). Similarly, changes in transepidermal water loss (TEWL) and the erythema index in the ND and NF groups were significantly different (p < 0.05). Furthermore, the wrinkle depth and Staphylococcus aureus population decreased in the NF group compared with those in the ND group (p < 0.05). The mean form factor, Shannon index, and Pediococcus population were significantly increased in the post-NF group compared with those in the post-ND group (p < 0.05). Finally, in the ND group, water-holding capacity was positively correlated with Enhydrobacter, whereas Enterobacteriaceae was negatively correlated with TEWL in the NF group. These results suggest that GOS inhibit the growth of harmful skin microbes and increase the population of beneficial microbes.