Iron is the metal found in blood. It is an essential mineral that plays a key role in transporting oxygen from the lungs to the rest of the body and carrying carbon dioxide back to the lungs to be exhaled. Iron is a crucial component of hemoglobin, a protein in red blood cells that binds to oxygen and gives blood its red color. Without sufficient iron, the body cannot produce enough healthy red blood cells, leading to iron-deficiency anemia, a common nutritional disorder.

Metals are electropositive elements because they tend to lose electrons easily. In chemical reactions, metals readily give away their outer electrons to form positive ions, making them good conductors of electricity and heat. This electron loss leads to the formation of cations, which contribute to the electropositive nature of metals.

Vitamins A, D, E, and K are called the fat-soluble vitamins, because they are soluble in organic solvents and are absorbed and transported in a manner similar to that of fats. Vitamin E deficiency, which is rare and usually due to an underlying problem with digesting dietary fat rather than from a diet low in vitamin E, can cause nerve problems.