K and the Renin-angiotensin-aldosterone System: New Insights into Their Role in Blood Pressure Control and Hypertension Treatment

Approximately 25% of the adult population is diagnosed with hypertension and it is therefore one of the biggest challenges for the health sector. The renin-angiotensin-aldosterone system (RAAS) adjusts effective circulating volume and ultimately blood pressure (BP). Accordingly, antihypertensive drugs targeting the RAAS have been a major focus in modern medical treatment. Low and high dietary K intakes are associated with increased or decreased BP and risk of cardiac failure, respectively, suggesting that dietary K augmentation has the potential to supplement or replace conventional anti-hypertensive drugs. Animal studies have indicated that the beneficial effects of high dietary K may be linked to a dominant regulatory role of plasma K on key renal transport proteins controlled by the RAAS. However, only a limited number of studies have investigated whether the reported mechanisms in animal models apply to humans. Furthermore, hypertension is often treated with so-called 'K sparing' drugs, thus complicating co-treatment with K supplementation. In this review, we revisit old concepts of RAAS effects in the kidney, relate them to effects of dietary K manipulation, and finally consider the clinical potential of treating hypertension with K supplementation alone or in combination with RAAS inhibitors. Collectively, a wealth of data suggest that increased dietary K intake may have beneficial effects on BP in the general population, but underlying medical conditions or current treatment regimens need to be carefully considered before implementing K supplementation in patients.