Abstract
The World Health Organization ranks hypertension the leading global risk factor for disease, specifically, cardiovascular disease. Blood pressure (BP) is higher in Westernized populations consuming Na(+)-rich processed foods than in isolated societies consuming K(+)-rich natural foods. Evidence suggests that lowering dietary Na(+) is particularly beneficial in hypertensive individuals who consume a high-Na(+) diet. Nonetheless, numerous population studies demonstrate a relationship between higher dietary K(+), estimated from urinary excretion or dietary recall, and lower BP, regardless of Na(+) intake. Interventional studies with K(+) supplementation suggest that it provides a direct benefit; K(+) may also be a marker for other beneficial components of a "natural" diet. Recent studies in rodent models indicate mechanisms for the K(+) benefit: the distal tubule Na(+)-Cl(-) cotransporter (NCC) controls Na(+) delivery downstream to the collecting duct, where Na(+) reabsorbed by epithelial Na(+) channels drives K(+) secretion and excretion through K(+) channels in the same region. High dietary K(+) provokes a decrease in NCC activity to drive more K(+) secretion (and Na(+) excretion, analogous to the actions of a thiazide diuretic) whether Na(+) intake is high or low; low dietary K(+) provokes an increase in NCC activity and Na(+) retention, also independent of dietary Na(+) Together, the findings suggest that public health efforts directed toward increasing consumption of K(+)-rich natural foods would reduce BP and, thus, cardiovascular and kidney disease.