Rehmannia glutinosa Libosch is a traditional Chinese medicinal herb with nourishing effect of the body.Radix Rehmanniae (the root of Rehmannia glutinosa Libosch)-also known as "Di-Huang" in Chinese, has been widely used in many recipes for the treatment of "thirst diseases".Depending on different processing methods, Di-Huang has been categorized into three types, named in Chinese as Xian-Di-Huang (fresh root), Sheng-Di-Huang (dried root) and Shu-Di-Huang (steamed root).Their efficiencies for therapy vary significantly, mainly due to differences in the chemical composition / concentration of the active ingredients present in these three types of Di-Huang.