Abstract: A multi vitamin and mineral dietary supplement composition for oral administration containing, per unit dose,(a) one or more divalent dietary mineral components selected from the group consisting of bioavailable calcium and magnesium, and in the further presence or absence of one or more additional non-ferrous mineral and vitamin components, adapted to be released in the upper gastrointestinal tract, and(b) a bioavailable iron component, present in controlled release form, so adapted so as to be subsequently released in a controlled manner lower in the gastrointestinal tract, and a method of preventing or treating iron deficiency using such compositions.