What is the function of sodium (salt) in the body?

Sodium plays a crucial role in regulating the body's fluid balance. It is essential for maintaining the proper amount of water in the cells and the extracellular fluid, which includes the blood plasma. Sodium helps to create osmotic pressure, influencing the movement of water in and out of cells. This balance is vital for various bodily functions, including blood pressure regulation, nerve transmission, and muscle function.

In the context of health, an appropriate amount of sodium is necessary for hydration and maintaining blood volume, while imbalances can lead to issues such as dehydration or hypertension. Therefore, the function of sodium in controlling the amount of water in the body is a key aspect of its importance in nutrition and health.