Disclosed is a method for producing an estrogen-like active intermediate (e.g., secoisolariciresinol) by culturing a lignan (e.g., a lignan derived from Eucommia ulmoides) together with a bacterium Lactobacillus acidophilus. Also disclosed a prophylactic/ameliorating agent for menopausal disorder and a functional beverage/food for preventing/ameliorating menopausal disorder comprising a lignan cultured together with a bacterium Lactobacillus acidophilus as an active ingredient.