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.