An object of the present invention is to provide a substance characterized by ability to reduce oxidized coenzyme Q10 and ability to stabilize reduced coenzyme Q10, which contains nutrients, has a favorable taste, and is excellent in general versatility, and a method for using the same. The present invention relates to a method for producing reduced coenzyme Q10 comprising reducing oxidized coenzyme Q10 with a particular amino acid. The present invention also relates to a method for stabilizing reduced coenzyme Q10 in the presence of a particular amino acid and a composition stabilized by the method.
