Described is a solubilization agent for solubilizing polyphenols, flavonoids and/or diterpenoid glucosides in aqueous liquids, wherein the solubilization agent consists of a mixture of: (a) one emulsifying polymer or a mixture of two, three or more emulsifying polymers, (b) one saponin or a mixture of two, three or more saponins, (c) one partially or fully water-miscible, preferably liquid, solvent or a mixture of partially or fully water-miscible, preferably liquid, solvents, preferably selected from the group consisting of ethanol, propylene glycol (1,2-propanediol), glycerin, triacetin (glycerin triacetate), diacetin (glycerin diacetate) and triethyl citrate, and (d) water. The solubilization agent is particularly suitable for sparingly water soluble polyphenols, flavonoids and/or diterpenoid glucosides. The invention also relates to compositions and (food or cosmetic) formulations comprising said solubilization agent. It further relates to a method for producing solubilization agents, compositions and (food or cosmetic) formulations.