The invention relates to the use of at least one unsaponifiable component of vegetable oil, in particular of avocado, soya bean and/or lupin oils, for the preparation of a medicament intended to stimulate the expression of TGF-.beta. or the expression of the plasminogen activator inhibitor PAI-1.The invention also relates to a method of cosmetic treatment comprising the application of at least one unsaponifiable component of vegetable oil as well as the use of the latter as additive in a food for human beings and/or for animals.