Normotensive Salt Sensitivity: Effects of Race and Dietary Potassium

• Published in: Hypertension (Dallas, Tex. 1979) Vol. 33; no. 1; pp. 18 - 23
• Main Authors: Morris, R. Curtis, Sebastian, Anthony, Forman, Alex, Tanaka, Masae, Schmidlin, Olga
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Heart Association, Inc 01-01-1999; Hagerstown, MD Lippincott
• Subjects: Adult; Aged; Arterial hypertension. Arterial hypotension; Bicarbonates - administration & dosage; Biological and medical sciences; Black or African American; Black People; Blood and lymphatic vessels; Blood Pressure; Cardiology. Vascular system; Clinical manifestations. Epidemiology. Investigative techniques. Etiology; Data Interpretation, Statistical; Humans; Hypertension - etiology; Hypertension - prevention & control; Linear Models; Male; Medical sciences; Middle Aged; Potassium Compounds - administration & dosage; Potassium Deficiency - complications; Potassium, Dietary - administration & dosage; Racial Groups; Sodium Chloride, Dietary - administration & dosage; Sodium Chloride, Dietary - adverse effects; White People; Human; Hypertension; Sensitivity; Diet; Sodium; Risk factor; Cardiovascular disease; Black American; Potassium
• DOI: 10.1161/01.HYP.33.1.18
• EISSN: 1524-4563
• ISSN: 0194-911X

Normotensive salt sensitivity, a putative precursor of hypertension, might be quite frequent in African Americans (blacks) and less frequent in Caucasian Americans (whites), but only when dietary potassium is deficient and not when maintained well within the normal range. We tested this hypothesis in 41 metabolically controlled studies of 38 healthy normotensive men (24 blacks, 14 whites) who ate a basal diet low in sodium (15 mmol/d) and marginally deficient in potassium (30 mmol/d) for 6 weeks. Throughout the last 4 weeks, NaCl was loaded (250 mmol/d); throughout the last 3, potassium was supplemented (as potassium bicarbonate) to either mid- or high-normal levels, 70 and 120 mmol/d. Salt sensitivity, defined as an increase in mean arterial blood pressure >or=to3 mm Hg with salt loading, was deemed "moderate" if increasing <or=to10 mm Hg and "severe" if increasing more. When dietary potassium was 30 mmol/d, salt loading induced a mean increase in blood pressure only in blacks (P<0.001), and salt sensitivity occurred in most blacks but not whites (79% vs 36% (P<0.02). Supplementing potassium only to 70 mmol/d attenuated moderate salt sensitivity similarly in blacks and whites; 120 mmol/d abolished it, attenuated severe salt sensitivity, which occurred in a quarter of affected blacks, and suppressed the frequency and severity of salt sensitivity in blacks to levels similar to those observed in whites. These observations demonstrate that in most normotensive black men but not white men, salt sensitivity occurs when dietary potassium is even marginally deficient but is dose-dependently suppressed when dietary potassium is increased within its normal range. Such suppression might prevent or delay the occurrence of hypertension, particularly in the many blacks, in whom dietary potassium is deficient. (Hypertension. 1999;33:18-23.)