Nutritional factors in high blood pressure

Abstract

Metabolism of Na⁺, Ca⁺ and Zn⁺ cations is clearly disturbed and involved in the development and maintenance of a hypertensive condition. These changes are closely related to each other; therefore, when their effects on primary hypertension (PH) are studied, they should always be globally (and not separately) considered. These changes of the aforementioned electrolytes in PH maintain a close, but unclear, relationship with various hormonal systems, mainly with the renin-angiotensin-aldosterone system. Daily control in the intake of these electrolytes (especially Na⁺ and Ca⁺⁺) remains a cornerstone in the adjuvant treatment of PH. Na⁺ dietary restriction is indicated in hypertensives showing higher sensitivity to salt; in most cases they have low (70%) plasma renin activity (PRA) and belong to one of the following five groups: black, elderly, obese or diabetic (type 2) patients, and mixed blood young people from our community with low levels of PRA and serum ionic calcium. For best results, this moderate Na⁺ restriction (4–6 g of NaCl) should always be accompanied by an oral calcium supplement, or at least the assurance that the subject takes an appropriate amount of Ca⁺⁺ (>800 mg/day) in his/her diet. Hypertensives with low PRA exhibit obvious changes of their calcium metabolism. We do not know the role of Zn⁺⁺ in the development of PH; however, older hypertensives with very low PRA have high urinary excretion of Zn⁺⁺ with low serum levels, a factor that could contribute to Zn⁺⁺ depletion in these hypertensive patients. The oral administration of calcium corrects the Zn⁺⁺ changes by a still unclear mechanism.