Sodium is a mineral that your body must have in order to function properly. The primary source of dietary sodium is sodium chloride, or salt, more than three quarters of which comes from processed foods. Although sodium is vital to a number of routine body functions, too much can have adverse effects, particularly for people who are sensitive to sodium. Excessive sodium can cause hypertension, which in turn can lead to other health problems. Nerve, Muscle Function Sodium is a mineral that carries an electrical charge, known as an electrolyte. Electrolytes facilitate muscle contraction and nerve cell transmission. Ions of sodium, potassium and chloride trigger muscle contractions and nerve impulses when they shift places across cell membranes. A nerve cell at rest has positively charged potassium ions and negatively charged chloride ions. When stimulated, potassium ions rush out of the cell as sodium ions rush in, creating an electrical signal or nerve impulse. A similar scenario occurs during the contraction of muscles. Fluid Balance Sodium also works in concert with potassium to maintain normal water balance in the body. Each of the minerals chemically attracts water to itself, thus assuring that optimal levels of hydration are maintained both inside human cells and outside the cells in extracellular spaces that surround them. In healthy people the body has a built in mechanism to guard against the effects of occasional excess levels of sodium, but continued intake of high amounts of sodium can eventually override this safety valve and lead to hypertension. Blood Volume Closely related to sodium’s role in the maintenance of normal fluid levels is the part it plays in controlling your body’s blood volume and thus blood pressure. Your body constantly monitors sodium concentrations and blood volume. If either blood volume or sodium levels get too high, your body stimulates your kidneys to excrete excess sodium, returning blood volume to normal levels.