Potassium (K)
Membrane Potential, Cellular Hydration & Blood Pressure Control. Potassium is the major intracellular cation in human cells (intracellular concentration ~140 mmol/L vs. extracellular ~4 mmol/L), generating the resting membrane potential across all excitable cardiac, nerve, and muscular cells.
How Potassium Works in Your Body
Potassium is required for critical enzymatic, structural, and electrochemical processes throughout the body:
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Resting Membrane Potential
The electrogenic Na+/K+-ATPase pump pumps 3 Na+ ions out for every 2 K+ ions in, maintaining the resting membrane potential (-70 to -90 mV) essential for action potential generation.
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Myocardial Repolarization
Voltage-gated potassium channels (IKr, IKs) mediate potassium efflux to drive Phase 3 repolarization of the cardiac action potential, resetting the myocardium for subsequent contractions.
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Natriuresis & Vascular Tone
High potassium intake suppresses renal sodium-chloride cotransporter (NCC) in the distal convoluted tubule, promoting sodium excretion, blunting sympathetic vascular tone, and lowering systemic arterial blood pressure.
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Glycogen & Protein Synthesis
Required for pyruvate kinase activation in glycolysis and cellular ribosome assembly for protein translation.
How Much Do You Need? (Daily Dietary Targets)
Recommended daily intake guidelines and safe upper limits for adults:
| Group / Life Stage | Recommended Target | Practical Advice |
|---|---|---|
| Adult Men | 3,400 mg/day (Adequate Intake) | Maintains normal cellular saturation, fluid balance, and enzyme function. |
| Adult Women | 2,600 mg/day (Adequate Intake) | Calibrated to balance menstrual needs, bone remodeling, and hormonal health. |
| Pregnancy & Lactation | 2,900 mg/day (Preg) / 2,800 mg/day (Lact) | Supports fetal development and replaces minerals transferred during breastfeeding. |
| Tolerable Upper Limit (UL) | Not Established for Dietary Sources | The highest chronic daily intake safe from precipitating organ distress or toxicity. |
Top Whole Food Sources
| Food Item | Serving Size | Nutrient Content | Relative Daily Density |
|---|---|---|---|
| Dried Apricots | 1/2 cup | 755 mg | |
| Cooked Lentils | 1 cup | 731 mg | |
| Acorn Squash (baked cubes) | 1 cup | 896 mg | |
| Potato (baked with skin) | 1 medium | 926 mg | |
| Atlantic Salmon (cooked) | 3 oz (85g) | 534 mg |
Signs You're Getting Too Much (Chronic Excess)
Consuming excess quantities through high-dose supplements or impaired kidney excretion can trigger side effects:
- Hyperkalemia: In healthy kidneys, excess dietary potassium is excreted via aldosterone-mediated secretion in the cortical collecting duct. In chronic kidney disease (CKD) or with ACE inhibitors/ARBs/spironolactone, serum K+ > 5.5 mmol/L occurs.
- Lethal Arrhythmias: Progresses on ECG from tall peaked T-waves, PR prolongation, and loss of P-waves to widening QRS complexes, sine wave patterns, ventricular fibrillation, and asystolic cardiac arrest.
Signs You're Not Getting Enough (Chronic Deficiency)
Prolonged low intake or excessive mineral loss produces progressive clinical complications:
- Hypokalemia (Serum K+ < 3.5 mmol/L): Caused by chronic inadequate intake paired with diuretic use, vomiting, or diarrhea.
- Cardiac Conduction Abnormalities: Prominent U-waves, flattened T-waves, ST-segment depression, premature ventricular contractions (PVCs), and tachyarrhythmias.
- Paralytic Ileus & Muscle Necrosis: Smooth muscle hypopolarization causes severe abdominal distension and paralytic ileus; skeletal hypoperfusion causes muscle cramps, flaccid paralysis, and rhabdomyolysis.
- Hypertension & Stroke: Chronic low intake promotes renal sodium retention and arterial vasoconstriction, raising hypertension and ischemic stroke risk.
Discover Synergistic Food Pairings
Learn which nutrients enhance the absorption of Potassium and which competing minerals you should avoid taking simultaneously.
View Nutrient Synergy Matrix →