摘要： All living organisms require metals. They have vital roles as catalysts, osmotic regulators, signaling molecules, and transport molecules. Many different metals are present in the human body, and carry out a range of essential functions: for example, oxygen travels in the blood bound to iron in hemoglobin, neurons communicate by changing their sodium and potassium levels, and metal catalysts like manganese in superoxide dismutase speed up biochemical reactions.1 Although metals are so essential, they make up less than 3% of the human body by weight. The most abundant metals found in the body belong to periodic groups I and II, including calcium (1.5%), potassium (0.4%), sodium (0.2%), and magnesium (0.1%). Essential transition metals are considered to be trace elements because they collectively make up less than 0.1% of body mass. These include zinc, chromium, vanadium, cobalt, copper, manganese, molybdenum, and tin.2,3