Trace elements are inorganic nutrients that humans require only in very small amounts (traces). In contrast to the bulk elements, trace elements – with the exception of iron – occur in human tissues at a mass fraction of less than 50 mg/kgKG.
Examples are
Iron
Iodine
Copper
Cobalt
Selenium
Chromium
Fluoride
Manganese
Molybdenum
Silicium
Vanadium
Zinc.
More information in the book “Bye bye, booze!“