Sodium is one of the body’s three major electrolytes (the other two being potassium and chloride). They exist as fully dissociated ions and are the main particles responsible for osmotic pressure in body fluids. Sodium is the primary extracellular electrolyte in body fluids. These substances are called electrolytes because they carry an electronic charge in their dissociated (ionic) state. Their ionic strength enables them to influence the solubility of proteins and other substances throughout the body. Most Americans consume enormous amounts of sodium, from 10 to 35 times more than the recommended daily intake. Dietary sodium is easily absorbed from the intestine, carried by the blood to the kidneys where it is either filtered out and returned to the blood or excreted.
When your doctor says you have high blood pressure, the medical name for your condition is “hypertension.” Blood pressure is created when the heart beats, propelling blood throughout the body. Blood pressure occurs in two distinct phases, corresponding to the contraction and relaxation of the heart muscle. When the heart contracts, it ejects a certain volume of blood out from its right side into the body’s largest artery, the aorta. This initial thrust causes “systolic” blood pressure, which is the upper number of your blood pressure reading. As the heart relaxes, the blood presses against the walls of the arteries as it circulates, causing “diastolic” blood pressure, which is the lower number in your reading. Systolic blood pressure is a measure of the heart’s blood output, while diastolic is determined by the resistance of arteries in the extremities to the flow of blood. If your blood pressure reading is “120 over 80,” this means your systolic pressure is 120 and your diastolic is 80.
A study published in the European Journal of Clinical Nutrition, assessed the association between daily sodium intake and hypertension. The study included 940 men who completed food frequency questionnaires and had their blood pressure and sodium excretion in urine measured. The results revealed that sodium excretion was significantly lower in treated hypertensive patients and higher in overweight/obese participants when compared with normotensive and normal-weight individuals, respectively. Researchers determined that an increased salt intake and an altered renal sodium handling were observed in overweight and obese participants. They also found that sodium intake was only slightly less in hypertensive participants on pharmacological therapy. Therefore, high salt intake and disrupted kidney function in obese and overweight people seem to contribute to hypertension.1
1 Venezia A, Barba G, Russo O, et al. Dietary sodium intake in a sample of adult male population in southern Italy: results of the Olivetti Heart Study. Eur J Clin Nutr. Mar2010.