Youth is a type of Elvin beverage that was the root of the fountain of youth legend. It comes in a clear bottle, with no markings, other than the label of youth in a bottle. It is described to taste refreshing and also slightly sweet. It is served cold usually, as shown its description in the first book. It consists of enzymes necessary for elvin health.
When Sophie first met Elwin, he prescribed her a double portion of this nutrient as she had been deprived of it for very long. It can be noticed that she drank both bottles in two gulps. Elwin also prescribes extra bottles when Sophie is severely injured.
Despite the fact that elves should think one per day, they are infrequently mentioned, and there was once a half drank bottle in Jolie's room.