The effects of sodium in the human body include maintaining electrolyte balance in the bloodstream and the proper working of the nervous and muscular systems. HealthCentral says that sodium is an important determinant of the volume of blood in the body and is an important factor in determining blood pressure. About 85 percent of sodium in the human body is found in blood and lymph fluid.
The human body gets most of its sodium from dietary sources. WebMD says that most food items have sodium as a natural constituent, besides that added in form of table salt (sodium chloride) and baking powder (sodium bicarbonate). Other sources of sodium include laxatives, aspirin, toothpaste and mouthwash.
WebMD lists the normal range of sodium in the bloodstream as 136 to 145 milliequivallents per liter. A value above this range is considered a high sodium level or hypernatremia, and results when a person is dehydrated, does not drink sufficient water, eats a high-sodium diet or has kidney disease. A value below this range is known as low sodium level or hyponatremia, and is a result of excess sweating, extreme diarrhea or vomiting, excessive water intake or poor nutrition. The adrenal glands produce a hormone called aldosterone, which helps the kidneys to control the level of sodium in the bloodstream and to excrete the excess through urine.