A COMPOSITION CONTAINING A PLURALITY OF WATER-SOLUBLE NANOCLUSTERS RANGING FROM 2 NM TO 500 NM IN DIAMETER. EACH OF THE NANOCLUSTERS CONTAINS ONE OR MORE METAL CATIONS, ONE OR MORE ANIONS, AND ONE OR MORE WATER-SOLUBLE LIGANDS. ALSO DISCLOSED IS A METHOD OF USING THE COMPOSITION FOR TREATING VARIOUS DISORDERS SUCH AS ANEMIA, HEARTBURN, AND DIABETES.