Blood pressure is the force exerted by blood against the arterial walls. It is determined by how much blood is pumped and the resistance to blood flow.
Acute (short term) regulation of blood pressure is achieved by the sympathetic nervous system. Long term regulation of blood pressure is primarily a function of the kidneys. The kidneys regulate blood pressure by helping control blood volume. The amount of fluid in the blood (blood volume) is determined by the amount of water and sodium taken in, and the amount of water and sodium excreted by the kidneys into urine (and lost through the gastrointestinal tract, lungs and skin).
If too much sodium or water is retained blood volume increases. An increase in blood volume causes the heart to pump harder to circulate more fluid . . . causing blood pressure to increase (hypertension).
The hormones renin, angiotensin II, aldosterone and vasopressin (ADH) increase blood volume, which results in increased blood pressure.
The incremental rise in blood pressure with age, and the prevalence of hypertension are directly related to sodium intake. A 1.3-g/day lower lifetime sodium intake translates into an approximately 5-mm smaller rise in systolic blood pressure as individuals advance from 25 to 55 years of age. Such sodium reduction is estimated to save 150,000 (U.S) lives annually.
Keep in mind: the majority of sodium consumption in the United States is derived from amounts added during food processing and preparation.
Source:
Reducing the Population Burden of Cardiovascular Disease by Reducing Sodium Intake.
Barry D Dickinson, PhD; Stephen Havas, MD, MPH, MS
Arch Intern Med 2007;167:1460-1468
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