Mulberry (Morus alba L.) is a deciduous tall tree of the Mulberry family. It has been used as a feed for silkworms since ancient times, and it is reported that the beginning of silkworm culture was introduced into China about 5,000 years ago and Japan during the Yayoi period. Mulberry has been cultivated since then.

"Mulberry bark", the root bark of mulberry, is listed as the middle grade goods in the oldest Chinese book, "Shennong Ben Cao Jing" which was published in approximately 2,000 years ago, and it has been used for antitussive, expectoration, and so on.

Mulberry leaves are rich in dietary fiber, calcium, vitamin E and polyphenols such as chlorogenic acid. In addition, mulberry leaves contain 1-deoxynojirimycin, galactopyranosyl-1-deoxynojirimycin and fagomine as characteristic functional ingredients. These ingredients are azasugars (iminosugars) which inhibit the activity of α-glucosidase. 1-deoxynojirimycin is similar to glucose in structure; therefore, it binds to α-glucosidase and inhibit the activity. (α-glucosidase: an enzyme that decomposes disaccharides into monosaccharides and absorb sugars in the small intestine) As a result, the degradation of disaccharides to monosaccharides is inhibited, and the absorption of glucose, etc. is suppressed. Therefore, the elevation of blood glucose level is inhibited.