Use of a composition comprising a compound of any of formulae I, II, Ila, III and Illa or a combination thereof wherein each R1 is independently C7-11 alkyl A and B are independently H or CO-R1 R2 is H or C1-4 alkyl M is a metal monocation (k=1) or dication (k=2) Y is 0 or NH and Z is 0, NH, CH2O or a bond for the manufacture of a medicament for stimulating erythropoiesis. Preferably, the composition further comprises human erythroporietin.