Salt and Electrolytes
Salt is important for human life because of its ability to supply the body with sodium, an electrolyte critical for cell function. Electrolytes also play an important role in blood pressure as they affect the blood's volume. In order for the body to function properly, levels of electrolytes such as sodium and potassium must be kept within narrow ranges because abnormally high or low levels can disrupt the electrical charges present in many cells. Cells such as neurons as well as muscle cells use sodium and potassium to create electric currents which are necessary for cells to function.
Salt and Osmosis
Because salt intake affects electrolyte levels, it also has an effect on how much fluid the body stores. When high levels of salt are present in the blood, the body attempts to dilute them by adding more fluid to the blood. As the American Heart Association explains, the kidneys have an important role in this process. When there are high levels of sodium or potassium in the blood, the kidneys will attempt to retain as much water as possible. This causes the overall amount of fluid in the blood to increase. The more fluid that is present in the blood, the higher the blood pressure is throughout the body and the harder the heart has to work to pump the blood.
Ouabain
Salt also can lead to hypertension by disrupting the balance of certain hormones in the body. As the University of Maryland Medical Center explains, excess salt increases the amount of a hormone called ouabain, which is made by the adrenal glands. Too much ouabain disrupts proteins that are needed to maintain the appropriate levels of sodium and calcium in the cells around the arteries. As a result, high salt levels lead to calcium building up in arterial cells, which causes them to contract. This leads to arteries narrowing and causes an increase in blood pressure.
