Potassium | Supplementopedia

Overview

Potassium (K⁺) is an essential monovalent cation.
It functions as a key electrolyte in human physiology.
Potassium primarily maintains intracellular fluid balance.
It supports nerve impulse transmission.
Potassium facilitates muscle contraction, including the heart’s rhythmic activity.

Blood Pressure and Hypertension: Adequate potassium intake (≥3,500 mg/day) is linked to lower blood pressure and reduced risk of hypertension (He et al., 2022).
Cardiovascular Health: Potassium supports cardiovascular health by promoting vasodilation via endothelial nitric‑oxide synthesis and attenuating arterial stiffness.
Nervous System: Potassium gradients support action‑potential generation, supporting cognition and reaction time.
Muscle Strength and Endurance: Adequate intake improves muscle strength and endurance, likely through optimal excitation‑contraction coupling.
Insulin Sensitivity and Diabetes Risk: Potassium modulates renal glucose handling, contributing to improved insulin sensitivity and reduced risk of type 2 diabetes (Miller & Himmelfarb, 2021).
Skeletal Health: Potassium helps maintain bone mineral density by reducing calcium excretion, supporting skeletal health.
Overall Health: These benefits underscore potassium’s role in cardiovascular, neuromuscular, metabolic, and skeletal health.

Electrochemical Gradient: Potassium’s primary action is the maintenance of the intracellular‑extracellular electrochemical gradient (the Na⁺/K⁺‑ATPase pump).
Na⁺/K⁺‑ATPase Pump: This ATP‑dependent transporter extrudes three Na⁺ ions and imports two K⁺ ions per cycle.
Intracellular Concentration: This process preserves a high intracellular K⁺ concentration (~140 mM) versus low extracellular levels (~4 mM).
Action Potentials: The gradient drives action potentials in neurons and muscle fibers; depolarization occurs when K⁺ exits cells through voltage‑gated channels, while repolarization requires rapid K⁺ influx through delayed rectifier channels.
Vascular Smooth Muscle: In vascular smooth muscle, K⁺ activates inward‑rectifier channels, hyperpolarizing cells, causing vasodilation, and lowering blood pressure.
Renal Function: In renal tubules, potassium influences the Na⁺/Cl⁻ cotransporter and the renin‑angiotensin‑aldosterone system, promoting natriuresis and reducing extracellular volume.
Combined Effects: The combined electrochemical and hormonal effects explain potassium’s influence on blood pressure, muscle contraction, and cellular metabolism.

RDA: The Recommended Dietary Allowance (RDA) for adults is 2,600 mg for adult females and 3,400 mg for adult males, typically obtained from diet.
Supplementation Range: Supplementation typically ranges from 99 mg (1 mmol) to 1,000 mg elemental potassium daily.
Therapeutic Doses: Higher therapeutic doses (up to 3,000 mg) are used under medical supervision for hypokalemia.
Administration: Potassium supplements are best taken with meals to enhance absorption and reduce gastrointestinal irritation.
Athletes: For athletes or individuals with high sweat losses, doses of 200–400 mg in the evening can help replenish nighttime losses.
Chronic Supplementation: Chronic supplementation above 4,700 mg/day is discouraged for the general population because of hyperkalemia risk.
Medical Supervision: Patients with chronic kidney disease, heart failure, or those on ACE inhibitors, ARBs, or potassium‑sparing diuretics should follow physician‑guided dosing.
Total Intake: Always verify total elemental potassium from all sources (food, medication, supplements) before exceeding the RDA.

Hyperkalemia: Excessive potassium (serum >5.5 mmol/L) can cause hyperkalemia, presenting as muscle weakness, arrhythmias, or cardiac arrest.
Side Effects: Common side effects of oral supplements include gastrointestinal irritation, nausea, and constipation.
Contraindications: Contraindications include severe renal impairment (eGFR < 30 mL/min/1.73 m²), acute renal failure, and conditions causing impaired potassium excretion (e.g., adrenal insufficiency).
Drug Interactions: Potassium‑sparing diuretics (spironolactone, amiloride), ACE inhibitors, ARBs, and NSAIDs may increase serum potassium; concurrent use warrants monitoring.
Diabetes and Insulin: Patients with diabetes mellitus on insulin therapy should be cautious, as insulin drives K⁺ into cells and may mask hyper‑ or hypokalemia.
Pregnancy and Lactation: Pregnant and lactating women can safely meet needs through diet; supplementation should be limited to 1,000 mg/day unless medically indicated.
Monitoring: Regular laboratory monitoring is essential when high‑dose supplementation is prescribed.

Elemental Properties: Potassium is a metallic element with atomic number 19 and symbol K.
Elemental Form: The elemental form is a soft, silvery‑white alkali metal with a body‑centered cubic lattice.
Supplement Forms: In supplements, potassium is typically present as an ionic compound (e.g., KCl, K₂CO₃, or K citrate).
Potassium Ion: The simplest molecular entity is the potassium ion (K⁺), which lacks a covalent structure; it is a monovalent cation with a full outer electron shell (configuration [Ar] 4s¹ → [Ar] 4s⁰ after ionization).
Ionic Radius: Its ionic radius is 138 pm (coordination number 6).
IUPAC Name: The IUPAC name for elemental potassium is “potassium.”
Hydration: In aqueous solution, K⁺ is highly hydrated, forming the [K(H₂O)₆]⁺ complex, which underlies its physiological solubility and transport.

Dietary Sources: Dietary potassium is abundant in fruits (bananas, oranges), vegetables (potatoes, spinach), legumes, nuts, and dairy.
Supplement Production: Commercial supplements derive potassium from mineral salts: potassium chloride is produced by the electro‑lysis of brine, potassium citrate from the reaction of potassium hydroxide with citric acid, and potassium carbonate from the Solvay process (calcination of potassium carbonate with limestone).
Purification: Pharmaceutical‑grade potassium salts undergo purification via recrystallization, ion-exchange, and filtration to meet USP/Ph. E. standards.
Quality Considerations: Quality considerations include verification of elemental potassium content, absence of heavy‑metal contamination, and correct anionic partner (e.g., chloride vs. citrate) to match therapeutic needs.
Quality Assurance: Good Manufacturing Practices (GMP) and third‑party testing (e.g., USP, NSF) ensure product purity and potency for consumers.