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.
