The effect of dietary calcium on hypertension.

The role of Ca in the prevention of hypertension is controversial, with some researches showing a lowering of blood pressure due to Ca supplementation and other studies that were not able to detect any ipo-tensive effect of this mineral. According to recent and less recent researches, Ca can lower blood pressure in two ways: - by increasing the endothelial synthesis of nitric oxide, a strong vasodilator; - by removing the misregulation of plasma renin activity in salt-sensitive subjects. As a consequence, an increase in Ca intake will be detected in the juxta-glomerular apparatus with a consequent reduction in renin and angiotensin synthesis. Renin is an enzyme, produced by kidney, that convert angiotensinogen, secreted from the liver, in angiotensin I. At pulmonary level angiotensin I is converted to angiotensin II by angiontensin-converting enzyme (ACE). Angiotensin II determines a blood vessel contraction and an increase in blood pressure.