Capillary cosmetic active ingredient, comprises an extract of Prunus amygdalus dulciscontaining at least 32 wt.% of oligopeptides having a molecular weight of 240-2000 Da. Independent claims are included for: (1) a capillary cosmetic composition to sheath the hair comprising the active ingredient (0.1-20 wt.%)； and (2) a process for capillary cosmetic treatment to preserve the internal structure of the hair fiber and/or restore the surface properties of damaged hair, and for increasing the sheathing, the brightness and/or volume of hair, comprising applying, on the dry or damp hair, the composition comprising the active ingredient.
