More than just metal.
“Trace elements” or “macronutrients” are terms given to elements required for human life but which, unlike “macronutrients” only occur in amounts less than 50mg per kg in the human body.
Iron is the most widespread trace element in our body; it is mainly responsible for oxygen transport in our blood, but also helps our cells recover energy and plays a role in our immune response and DNA synthesis.
Some key sources of iron include pig liver, veal, legumes and oats, though the iron found in animal foodstuffs has considerably greater bioavailability than that in vegetable foodstuffs. Spinach was once believed to be a major source of iron, but this was based on an analysis error.
Another important trace element is copper, which is partly responsible for the formation of erythrocytes (red blood cells). It also supports the formation of melanin in the skin, stimulating your immune system and reducing inflammation A copper deficiency can contribute to vascular disease.
Some good sources of copper include cocoa, offal, fish, crustaceans, nuts, some vegetables and full-grain cereals.
Like every naturally occurring substance, however, even trace elements are poisonous in too large amounts.