STUDIES IN DIETARY MODIFICATION OF SODIUM, POTASSIUM AND FIBER: EFFECTS ON METABOLIC CORRELATES OF BLOOD PRESSURE REGULATION

Three studies were conducted with the objective of investigating the metabolic consequences and value of modifying dietary intake on blood pressure regulation. In the first phase, normotensive adults received 0, 2.36, 4.72 or 9.44 meq potassium per day. No changes were observed in the amounts of sodium in feces or urine. Serum sodium levels rose with potassium supplementation. A progressive fall in potassium excreted in feces and an expected increase in urine potassium were observed with increments in potassium intake. Serum potassium concentrations were unaffected by supplementation, urinary sodium/potassium ratios fell with higher potassium intakes but blood pressure values remained unchanged. In the second phase all possible combinations, of two levels each of sodium, potassium and fiber were fed to hypertensive rats and their normotensive controls. The amounts of sodium and potassium in serum, urine and feces appeared to depend on intake. However, increments in fiber increased the amount excreted in feces and decreased amounts in urine. Hypertensive rats showed decreased serum sodium concentrations on high sodium intakes. Serum potassium levels did not rise in these rats with higher potassium or fiber intakes, as it did in normotensive rats. This study provides a basis for further studies on nutrient interaction effects on blood pressure regulation. In the last phase, Kenyan physicians surveyed indicated that diet was the most important etiological factor in the development of idiopathic hypertension. However, they used drug therapy more often and gave verbal advice to reduce sodium intake to their hypertensive patients. Physicians trained in Kenya tended to regard sodium reduction as the most important dietary modification for treating hypertension. Those trained abroad regard weight control and reduction of fat intake as the major dietary modification required to manage hypertension. Due to drug side effects and their escalating costs that developing countries such as Kenya can hardly afford, alternatives to drug use are urgently needed.