**1. Introduction**

Trace elements possess important therapeutic properties. First, binding to specific macromo‐ lecules (enzymes, nucleic acids, etc.) they influence important chemical and biological processes; second, they interact amongst themselves synergistically to amplify their individual reactions. Some trace elements are also metals. Not all metals are trace elements. Metals have been used therapeutically for hundreds of years. Use of metals in the treatment of human diseases began with discoveries with gold used initially in patients with tuberculosis followed by rheumatoid arthritis. Gold identified an immunological pathogenesis in the etiology of rheumatoid arthritis, thus metals may be efficacious in other human conditions that are immunological in etiology. The antineoplastic potential of metals was further disseminated by the development of less toxic compounds such as platinum. Third, use of metals in the treatment of human cancers has improved the therapeutic effectiveness response to this diverse group of diseases. Fourth, lithium use in clinical medicine revolutionized treating psychiatric mood disorders. Central to the biological action of lithium is its ability to influence brain and central nervous system chemistry, thereby providing spectacular results in the treatment of affective and other psychiatric mood disorders, in particular, suicide prevention. Discoveries defining alternative non-psychiatric clinical use of lithium continue to intrigue clinical medicine based upon a key discovery demonstrating lithium can effectively influence stem cells. Halotherapy is using salt compounds as initial and maintenance therapy of human respiratory aliments. Used by the Greeks and Romans, halotherapy has existed for thousand of years. It is associated with the therapeutic effectiveness attributed to spas. Today halother‐ apy has gained resurgence with its use as personalized medicine in the treatment of human diseases.

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