The object of the invention is to provide a functional unknown material in which a natural product is used as a raw material. One embodiment of the invention is a yeast fermentation product of the nest of birds belonging to the genus Collocalia, family Apodidae. This yeast fermentation product can be used as a pharmaceutical, quasi-drug, food for health supplementation, food for nutritional supplementation, processed food, or soft drink. Another embodiment of the invention is a composition containing a yeast fermentation product of the nest of birds belonging to the genus Collocalia, family Apodidae. This composition is a pharmaceutical, quasi-drug, food for health supplementation, food for nutritional supplementation, processed food, or soft drink. Yet another embodiment of the invention is a method for producing a material having as the raw material the nest of birds belonging to the genus Collocalia, family Apodidae. In this method, yeast is added to the raw material. In addition, the raw material is fermented by the yeast.
