Abstract: Provided is a clock gene expression level regulator which has a long history of being eaten and is high in safety, easily obtainable and superior in processability. Specifically provided is a clock gene expression level regulator comprising, as an active component, at least one compound selected from the group consisting of oleuropein, 3,4-DHPEA-EA, derivatives thereof, and salts of the foregoing. The clock gene expression level regulator of the present invention can regulate the expression levels of the Per1 and Bmal1 genes in antiphase to each other, thereby entraining the expression rhythms of the Per and Bmal genes to their normal phases.

Abstract: The purpose of the present invention is to provide a means for promoting the in vivo absorption of hydroxytyrosol or a derivative thereof, prolonging the in vivo residence time, and sustaining the effect. As a result of in-depth studies, the present inventors discovered that the in vivo absorption of hydroxytyrosol or a derivative thereof can be promoted and the in vivo residence time can be prolonged by using hydroxytyrosol or a derivative thereof in combination with a compound having a galloyl group.