| Element | Ionic form | Transport mechanism | Functions | References |
| Molybdenum | | Ion transporters | Cofactor or activator of certain enzymes (e.g., nitrogen fixation, nucleic acid metabolism, and aldehyde oxidation) | |
| Cobalt | Co2+ | Ion transporters, DMT1 | Constituent of vitamins B12 | |
| Copper | Cu+, Cu2+ | ATP 7A catalyzes, Cu-transporting ATPase | Constituent of plastocyanin and cofactor of respiratory enzymes. | [28–32] |
| Iodine (heaviest trace element) | I | Diffusion and ion transporters | Constituent of thyroxin, triiodothyronine, and other thyroid hormones. | |
| Boron | , | Ion transporters | Activates arabinose isomerase. | |
| Zinc | Zn2+ | Enzyme and protein carriers | Cofactor of certain enzymes (e.g., carbonic anhydrase, carboxypeptidase) | |
| Manganese | Mn2+, (Mn2+).4 | DMT1 | Cofactor of certain enzymes (e.g., several kinases, isocitric decarboxylase). | |
| Iron | Fe2+, Fe3+ | DMT1 | Constituent of haemoglobin, myoglobin, and cytochromes. | |
| Magnesium | Mg2+ | Ion transporters | Constituent of chlorophyll activates ATPase enzyme | |
| Sulphur | | Ion transporters | Constituent of coenzyme A, biotin, thiamine, and proteins. | |
| Phosphorus | , H2PO4 | Ion transporters | Constituent of lipids, proteins, nucleic acids, sugar phosphates, and nucleoside phosphates. | |
| Calcium | Ca2+ | Ion transporters | Constituent of plant cell walls; matrix component of bone tissue; cofactor of coagulation enzymes. | |
| Potassium | K+ | Diffusion and ion channels | Cofactor for pyruvate kinase and K+-stimulated ATPase. | |
| Sodium | Na+ | Diffusion and ion channels | Perform nerve functions, acid base balance, and homeostasis | |
| Cadmium | Cd2+ | DMT1 | | |
| Zinc2+ | Zn, ZIP6 (LIV-1) | Zinc transporters | Metabolic cellular functions | [33] |
| Aluminium | Al | Transferrin-receptor mediated endocytosis | | |
| Metal ions | Fe, Cu, and Ag | Multiple transport proteins, Na+/K+ pump, K+ channel, Na+ lysine symporter channel, and sodium-lysine transporter | Work as electrolyte in plasma | [34] |
| Metal ions | Fe, Cu, and Ag | Membrane transporter proteins such as ABC transport proteins | Enzymatic cellular functions | [35] |
| Free metal ion and complexes | Fe, Cu, Ag oxides, and sulphates | Transferrin carries metal species, such as the free metal ion and complexes of the metal with an amino acid or protein. | Transmigration of proteins | [36, 37] |
| Divalent metals | Fe, Cu, Ag, and zinc | (DMT1, DCT1, and Nramp2) transports, ferroprotein, | | [36, 38, 39] |
| Divalent metals | Fe3+ and cobalt (Co2+), Ca++, Fe++, Mn++, Cd++, Cu++, Ni++, Pb++, Zn ++ | Divalent metal transporter 1, divalent cation transporter 1 (DCT1) | Iron-overload disorders | [40, 41] |
| Trivalent metals | Al and Mn | Diferric transferrin | | [42] |
| Methyl mercury | | Transport by the L-cysteine system | | [43] |
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