Potassium (Elemental K)

Direct Answer

Potassium is the primary intracellular cation (140 mEq/L intracellular vs 4 mEq/L extracellular), maintaining the cellular resting membrane potential via the Na+/K+-ATPase pump and regulating vascular tone. Adequate Intake (AI) is 3,400 mg (men) / 2,600 mg (women).

Source: NIH ODS / NASEM (2019) / WHO · Last reviewed Aug 28, 2026

Specs

Nutrient Type	Essential Macromineral / Major Intracellular Electrolyte
Adult Adequate Intake (AI)	3,400 mg / day (Men) / 2,600 mg / day (Women) (WHO Target: >3,510 mg/day)
Tolerable Upper Limit (UL)	None Established (Whole foods; healthy kidneys clear excess; renal impairment requires clinical restriction)
Chemical Forms	Potassium Citrate, Potassium Chloride (KCl / Salt substitute), Potassium Gluconate
Primary Biological Function	Na+/K+-ATPase resting membrane potential (-70mV), Cardiac myocardial repolarization, Endothelial nitric oxide vasodilation (lowers blood pressure), Blunts sodium-induced fluid retention
Deficiency Condition	Hypokalemia (Serum K+ < 3.5 mmol/L): Cardiac arrhythmias (U-waves, ventricular tachycardia), Muscle weakness, Ileus, Hypertension
Top Whole Food Sources	Baked Russet Potato (with skin), Orange Sweet Potato, Spinach, Bananas, Atlantic Salmon, Black Beans, Hass Avocado, Coconut Water
Dietary Sodium-to-Potassium Ratio	Ancestral human ratio was 1:4 (Na:K); modern Western diets average 2:1, significantly contributing to hypertension

Vascular Endothelial Hyperpolarization

Elevated dietary potassium stimulates inward rectifier potassium channels (Kir) and Na+/K+-ATPase pumps in vascular smooth muscle cells, inducing hyperpolarization and profound arterial vasodilation that lowers systemic systolic blood pressure.