Minerals and Ions

Inorganic substances — small in quantity, indispensable in function.

Major examples

• Sodium and potassium — the chief ions of body fluids; their movement across membranes drives nerve and muscle signals.
• Calcium — hardens bone and teeth, triggers muscle contraction, and helps blood clot.
• Phosphate — part of bone, DNA, cell membranes, and the cell’s energy molecule (ATP).
• Chloride — the main negative ion of extracellular fluid; a component of stomach acid.
• Magnesium — required by hundreds of enzymes.
• Trace minerals — iron, zinc, iodine, copper, selenium, and others, each needed in tiny amounts for a specific job (iron for hemoglobin, iodine for thyroid hormone).

What they do

• Electrical signaling — ion gradients are the basis of every nerve impulse and heartbeat.
• Structure — minerals harden the skeleton.
• Enzyme support — many enzymes cannot work without a metal ion.

Key idea

Unlike the other biomolecules, minerals cannot be manufactured by the body — they must all come from the diet.