A composition for use in medicine or as a dietary supplement, the composition comprising at least one complex or salt of trivalent metal cation (Me3+) with inorganic polyphosphate (polyP), wherein the trivalent metal cation (Me3+) is selected from the elements of the group consisting of Al, Ga, In, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.