A composition of matter which comprises a metallic complex of the formula MZ+LnI wherein M is a metal ion of nutritional or therapeutic value; Ln is one or more oligopeptides wherein at least one oligopeptide comprises at least one amino acid selected from the group consisting of nonprotein amino acids and synthetic amino acids; n=1-3, Z=1-6. The metal ion of the metallic complex is selected from the group consisting of chromium, zinc, manganese, magnesium, calcium, copper, iron, vanadium, cobalt, molybdenum, germanium, selenium, and indium. The invention further provides food or drink compositions or dietary supplements which comprise the metallic complex of the invention.