mineral · for muscle cramps
Potassium
Muscle cells need potassium to hold their electrical charge steady. Low potassium makes them fire too easily.
Say that in clinical terms
Potassium is critical for maintaining the resting membrane potential of muscle cells. Hypokalemia causes depolarization of the cell membrane, increasing excitability and spontaneous contractions leading to cramping.
How strong is the research?
Among 72 ultra-distance runners, electrolyte levels were no different in those who cramped.
1 paper read, 1 against.
Who was studied: This applies to a diagnosed potassium deficiency. Ordinary cramp is rarely that.
No qualifying RCT was found that administered a potassium supplement to humans and measured muscle cramp outcomes. A recent systematic review and meta-analysis of 13 electrolyte-supplementation RCTs for muscle pain syndromes (published in 2026, ScienceDirect) found no eligible trials of potassium supplementation in isolation for cramp or myalgia outcomes; the 10 included trials all studied magnesium. A Cochrane-style search for nocturnal leg cramp RCTs returned trials of magnesium, vitamin K2, and quinine — none of potassium. A search for exercise-induced cramps returned RCTs testing pickle juice and cramp-reduction approaches but again no potassium supplementation arms. The claim we current
How much to take
daily with meals
99–200 mg
Supplement doses are limited to 99mg per capsule (FDA). Increase dietary intake (bananas, potatoes, coconut water) alongside supplementation.
Before you take it
- No Tolerable Upper Intake Level (UL) established for potassium in healthy adults (National Academies 2019 DRI update; NIH ODS); healthy kidneys efficiently excrete excess dietary and supplemental potassium. Risk is concentrated in those with impaired renal function.
- Individuals with chronic kidney disease (CKD), adrenal insufficiency, diabetes-associated nephropathy, or any other condition impairing renal potassium excretion face hyperkalemia risk from supplemental potassium that can cause life-threatening ventricular arrhythmias and cardiac arrest.
- Clinically significant additive hyperkalemia risk when potassium is combined with: ACE inhibitors (lisinopril, enalapril, ramipril), ARBs (losartan, valsartan, olmesartan), potassium-sparing diuretics (spironolactone, triamterene, amiloride), NSAIDs (particularly in those with any renal impairment), high-dose trimethoprim, or heparin.
- FDA caps OTC supplement servings at ≤99 mg potassium per serving to reduce risk of accidental hyperkalemia. This is far below the adequate intake for adults (2,600–3,400 mg/day from food) and below doses used in clinical trials demonstrating blood pressure benefit; doses sufficient for therapeutic effect require medical supervision.
- Solid oral potassium chloride tablet formulations (especially enteric-coated forms) carry a risk of GI mucosal ulceration, perforation, and stricture; FDA requires labeling for this risk. Liquid, powder, and food-sourced potassium do not carry this GI risk.
- Insulin deficiency or poorly controlled diabetes impairs cellular potassium uptake, increasing hyperkalemia risk in this population.
- OTC potassium supplements at the FDA-capped ≤99 mg per serving are pharmacologically insufficient to correct true clinical hypokalemia (which typically requires 40–120 mEq/day under medical supervision); users with genuine hypokalemia-related muscle cramps need medical evaluation and prescription-level repletion, not OTC supplementation.
What we make of it
Sports research points at nerve control, not electrolytes, as the cause of exercise cramp.
The detail
Low potassium does cause cramp in a clinical setting, but that does not carry over to most people. Sports science has moved toward altered nerve and muscle control as the main driver of exercise cramp, and studies comparing runners who cramp with runners who do not find no difference in their electrolyte levels.