Lactobacillus gasseri Decreases p-Cresol Levels in Serum and Cecum and Improves Skin Characteristics in Mice Fed with Tyrosine-Rich Diets

Investigation of the influence of alive or dead dietary lactic acid bacteria, specifically Lactobacillus gasseri, on mice fed a tyrosine-rich diet was conducted in this study. Mice fed a tyrosine-rich diet exhibited increased p-cresol levels in the serum and cecum and deteriorated skin characteristics in terms of skin moisture and transepidermal water loss. These conditions were partially ameliorated by the intake of lactic acid bacteria. To gain insight into the mechanism, the intestinal microbiota of mice fed lactic acid bacteria was examined. The results revealed an increase in bacteria including genus Faecalibacterium and Lactobacillus in fecal samples from mice fed lactic acid bacteria. Muribaculaceae was most associated with the added group of alive or dead L. gasseri. These findings indicate that lactic acid bacteria inhibit the conversion of tyrosine to p-cresol in the colon, thereby ameliorating skin disorders.