Which mineral is essential for maintaining proper fluid balance and nerve function?

Sodium is essential for maintaining proper fluid balance and nerve function in the body. It plays a crucial role in regulating extracellular fluid volume and is vital for the proper functioning of cells. Sodium ions are involved in the transmission of electrical impulses in the nervous system, enabling communication between nerves and muscle contractions. When sodium levels are adequate, cells can maintain their hydration and osmotic balance, which is critical for overall physiological functioning.

Calcium is primarily known for its role in bone health and muscle contraction, while iron is crucial for oxygen transport in the blood. Magnesium does support nerve function and muscle contraction but is not as directly involved in fluid balance as sodium is. Sodium's specific functions make it the key mineral for these essential processes.