Which mineral is primarily involved in controlling body fluids and heart function?

• A. Sodium
• B. Magnesium
• C. Potassium
• D. Phosphorus

Answer: (C)

Potassium is the mineral primarily involved in regulating body fluids and heart function. It is the major intracellular positively charged ion, helping to keep the internal fluid balance of cells and enable the electrical signals that make muscles, including the heart, contract. The heart’s rhythm depends on potassium helping to set the correct electrical impulses; imbalances can lead to abnormal heart rhythms. The movement of potassium and sodium across cell membranes, controlled by the Na+/K+-ATPase pump, is central to fluid balance and nerve–muscle activity. While other minerals like sodium influence extracellular fluids and blood pressure, and magnesium and phosphorus contribute to muscle and energy processes, potassium has the strongest direct link to both body fluid control and heart function.