Potassium

Potassium
Chemical formula	K (element); biological form mainly K⁺
Solubility	Potassium salts are water-soluble; chloride and citrate are common forms
Bioavailability	Nearly complete absorption; renal excretion adjusts balance; diuretics and low magnesium increase loss
Dietary sources	Fruits, potatoes, milk, broth, coconut water; orange juice is high in potassium and vitamin C
RDA (adults 19–50 y)	~2,600–3,400 mg/day (US adult adequate intake)
Upper limit	No established UL for food potassium; supplements require caution in kidney disease

Potassium (K⁺) is the main intracellular cation, paired with Magnesium, while Sodium and Calcium dominate extracellular fluid when metabolism is efficient.

Stressed or de-energized cells lose magnesium and potassium and absorb sodium and calcium in his calcium article. Hypothyroidism and inflammation shift that balance.

History

Etymology

The English name comes from "potash" (ashes leached in a pot, a traditional source of potassium carbonate). The chemical symbol K comes from Latin kalium, itself from Arabic al-qaly ("the ashes").

Humphry Davy isolated potassium in 1807 by electrolysis of molten potash, the first metal isolated by electrolysis.

Structure/Chemical properties

Potassium (atomic number 19) sets resting membrane potential with sodium. Mainstream physiology treats serum potassium as a critical electrolyte for heart rhythm and nerve conduction.

Function/Mechanism of Action

Insulin itself has been found to account for only about 8% of the "insulin-like activity" of the blood, with potassium being probably the largest factor.

— Ray Peat

Peat used blood glucose and sodium concentration to modulate inflammatory reactivity in MS writing: high glucose made even strong antigens mildly irritating, while very low glucose made mild irritants deadly; varying sodium had a weaker parallel effect. Serum potassium appears among useful thyroid-context labs in his hypothyroidism article.

Potassium citrate supports bone mineral balance in epidemiology Peat cited on the calcium page.

Medical uses/Effects

Mainstream medicine uses potassium chloride for deficiency and potassium citrate for some kidney stones. Peat's dietary emphasis is fruit-and-milk patterns with adequate minerals rather than isolated potassium megadoses. Pair with Magnesium, Thyroid, and Glucose stability in his MS and hypothyroidism themes.

A meta-analysis of 22 randomized controlled trials found increased potassium intake lowered systolic blood pressure by about 3.5 mmHg and diastolic by about 2 mmHg in adults, with a larger effect in people with existing hypertension and no adverse effect on blood lipids, catecholamines, or kidney function. This lines up with Peat's fruit-forward, potassium-rich dietary pattern rather than isolated high-dose supplementation, which carries hyperkalemia risk in kidney disease.

Side/Adverse effects

Hyperkalemia from supplements or renal failure causes arrhythmia. Hypokalemia follows diuretics, vomiting, and aldosterone excess. Low Magnesium worsens potassium loss in standard clinical teaching.

Dosing

No fixed supplement dose given. Orange juice supplies potassium and vitamin C; Peat warned against pairing high vitamin C drinks with iron-heavy meals when limiting iron uptake. See Harm reduction.