Photoprotective effects of Bifidobacterium breve supplementation against skin damage induced by ultraviolet irradiation in hairless mice

Summary Background Probiotics have been considered to affect not only the gut but also the skin. This study aimed at examining whether oral administration of live B ifidobacterium breve strain Y akult ( BBY ), a typical probiotic, could exert photoprotective effects in hairless mouse skin. Methods BBY cell suspensions and fermented milk containing BBY ( BBYM ) were orally administered to hairless mice for 9 and 14 days, respectively. Mice were irradiated with ultraviolet ( UV ) light daily for the last four consecutive days. Twenty‐four hours after the final irradiation, skin elasticity, appearance, elastase activity and interleukin ( IL )‐1β levels were evaluated in the dorsal skin. Results BBY and BBYM significantly prevented UV ‐induced deleterious changes in skin elasticity and appearance. BBY suppressed the increases in both elastase activity and IL ‐1β levels in the skin. There was a significant negative correlation between elastase activity and the ratio of elastic recovery to total deformation and a significant positive correlation between elastase activity and the area ratio of furrows, independent of UV irradiation or BBY administration. Conclusion Our findings suggest that oral administration of probiotic BBY has the potential to prevent UV ‐induced skin damage, supporting the hypothesis that probiotics are beneficial not only to the intestine but also to the skin.