The present invention provides a composition comprising or consisting of components (a) (i) at least one mono-alkanoyl glycerol ester, wherein alkanoyl is selected from C 4 to C 21 alkanoyl, preferably from octanoyl and decanoyl; and (b) (i) at least one compound selected from cholesterol, phosphatidyl cholines and phosphatidyl glycerols, wherein the acyl moieties of the phosphatidyl moieties are independently selected from C 6 to C 21 alkanoyl and C 6 to C 21 alkenoyl.