Potassium

The sodium–potassium pump drives potassium into cells, creating the high-potassium resting potential; repolarization depends on potassium efflux through channels. Bananas, potatoes, legumes, dairy, and dark leafy vegetables are dietary potassium mainstays. Heavy sweating or diuretics increase potassium loss. Food potassium often comes with citrate and phosphate; the anion is not the same as in potassium chloride salt.

Potassium promotes urinary sodium excretion and relaxes vascular smooth muscle; DASH-style high-potassium fruit-and-vegetable patterns and blood-pressure trials often relate to this. Potassium citrate and potassium bicarbonate also bring an alkali load; potassium chloride does not. To get enough potassium, fruits, vegetables, legumes, and potatoes still lead; salt substitutes are concentrated potassium chloride, with a different anion from vegetable potassium. When kidney function is normal, food potassium is the main way to raise intake.

Heavy sweating loses potassium and sodium together; low intracellular potassium raises weakness and arrhythmia risk. Bananas, potatoes, and legumes are the diet mainstays for post-exercise potassium; people who cramp easily after endurance training or hot work often match gaps on this electrolyte-recovery path.