Which mineral is essential for maintaining fluid balance in the body?

Sodium is essential for maintaining fluid balance in the body due to its role in regulating osmotic pressure and fluid movement between different compartments of the body, such as cells and the extracellular space. It acts as a primary electrolyte, helping to retain water and contributing to blood volume and blood pressure.

Sodium works closely with other electrolytes, particularly potassium, to facilitate various physiological functions, including the transmission of nerve impulses and muscle contraction. Its regulation is crucial for homeostasis, and the kidneys play a significant role in managing sodium levels, which in turn affects fluid retention and distribution throughout the body.

Although calcium and potassium also have important functions in overall health, calcium primarily supports bone health and muscular function, while potassium mainly helps manage blood pressure and works opposite to sodium in certain contexts. Iron is essential for oxygen transport in the blood but does not directly influence fluid balance. Therefore, sodium is identified as the key mineral responsible for maintaining fluid balance.