The invention describes the use of a nanodispersion, which comprises: a) a membrane-forming molecule, b) a co-emulsifier, c) a lipophilic component, and d) a water-soluble ingredient sensitive to oxidation in cosmetic end formulations, the nanodispersion being obtainable by (&alpha；) mixing the components (a), (b) and (c) until a homogeneous liquid is obtained (so-called nanodispersion pre-phase), and (&bgr；) adding the water or aqueous phase (discontinuous phase) which contains the water-soluble ingredient and optionally the non-aqueous polar organic solvent to the liquid obtained in step (&alpha；). Component (d) is preferably ascorbic acid or vitamin C.
