The Effect of Alpha-Glucan Oligosaccharide on Facial Skin Flora

Abstract

Skin flora consists of various types of bacteria. It has been reported that skin flora is involved in the maintenance of skin homeostasis. Previous studies have revealed that glucan oligosaccharide (GOS) improves the growth of beneficial bacteria and inhibits the growth of pathogenic microorganisms in the intestines. It is possible that the selective effect of GOS is useful for improving facial skin flora. In this study, we investigated the effectiveness of α-GOS on facial skin flora in clinical trials. For this test, gel formulations including α-GOS were prepared and then applied on the entire face of volunteers twice a day for 2 weeks. Facial skin flora was collected with a wet swab before and after the sample treatment and its composition was analyzed by metagenomic analysis using DNA sequences. The Simpson index (SI) is an indicator of the microbial diversity of facial skin flora. The results showed that the SI was specifically improved in the group of volunteers with low initial SI. Furthermore, the abundance ratios of Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus) tended to increase and tended to decrease, respectively, with the treatment with α-GOS in all subjects. In the group of volunteers with low initial SI, the increased tendency of abundance ratio of S. epidermidis became clear and Cutibacterium acnes (C. acnes) was shifted to the optimal abundance ratio. In conclusion, these results suggest that α-GOS might contribute to the regulation of facial skin flora by improving the balance of beneficial and unbeneficial bacteria and their diversity. Following the modification of facial skin flora in 2 weeks, it would be expected that α-GOS would affect the physiological parameters of the skin. Altogether, α-GOS is expected to be useful as a cosmetic ingredient to regulate facial skin flora.