Potassium

What It Does

The sodium-potassium ATPase pumps three sodium ions out of each cell for every two potassium ions it brings in. About 98% of body potassium sits inside cells, and the kidneys, under the control of aldosterone, keep serum potassium in a narrow band of roughly 3.5-5.0 mmol/L. Insulin and adrenaline shift potassium into cells within minutes. Small departures from the normal range in either direction change cardiac excitability, which is why both low and high potassium cause arrhythmias.

Potassium lowers blood pressure, mostly by increasing urinary sodium excretion and relaxing vascular smooth muscle. In a 2013 meta-analysis, higher potassium intake lowered systolic pressure by about 3.5 mm Hg in people with hypertension and was associated with a 24% lower risk of stroke (Aburto 2013). The balance between sodium and potassium may matter more than either alone: in long-term follow-up of the Trials of Hypertension Prevention, the urinary sodium to potassium ratio predicted cardiovascular events better than sodium or potassium separately (Cook 2009). The strongest outcome trial tested a salt substitute rather than a pill. In about 21,000 older rural Chinese adults with prior stroke or hypertension, replacing regular salt with a 75% sodium chloride, 25% potassium chloride blend reduced stroke, major cardiovascular events, and death over five years (Neal 2021). People with serious kidney disease or on potassium-sparing drugs were excluded.

Low serum potassium usually comes from losses, not diet: thiazide and loop diuretics, vomiting, diarrhea, and laxative overuse. Low magnesium makes the kidneys waste potassium, and potassium often will not stay corrected until magnesium is replaced.

Forms and Bioavailability

Absorption ratings are broad tiers. Head-to-head human trials rarely support a finer ranking among well-absorbed forms.

Labels column: number of labels named as potassium products that list this form. A product can list more than one form, and some labels do not state a form at all.

Under FDA rules, solid oral potassium products with more than 99 mg per unit must carry a warning about small-bowel lesions, because concentrated potassium chloride tablets once caused ulcers and strictures. Supplement makers stop at 99 mg to avoid it. Prescription potassium is dosed in milliequivalents (1 mEq is about 39 mg), comes in wax-matrix or microencapsulated forms, and is used to treat a measured deficit. Citrate is metabolized to bicarbonate and alkalinizes the urine, which is why prescription potassium citrate prevents some kidney stones. Chloride is the right choice when low potassium comes with metabolic alkalosis, as it usually does with diuretics. All the soluble salts are well absorbed; they differ in what they carry with the potassium.

Typical Dosing

Most over-the-counter potassium supplements contain 99 mg or less, about 3% of the AI. Prescription potassium chloride, commonly 10-20 mEq (390-780 mg) per dose, treats hypokalemia with lab monitoring.

Food sources: dried apricots, lentils, acorn squash, prunes, potatoes, kidney beans, bananas, yogurt.

What to Look For

Get potassium from food: potatoes, beans, lentils, dried apricots, squash, bananas, yogurt, and leafy greens. Several servings of fruits and vegetables a day close most of the gap that a 99 mg capsule cannot. Use the Electrolyte Needs calculator to estimate how far your intake falls short.

If a clinician has found low potassium, the treatment is prescription potassium with a follow-up level. Taking a handful of 99 mg capsules to approximate a prescription dose defeats the safety rationale for the limit.

Check electrolyte powders and salt substitutes. Drink mixes often carry 200-500 mg per serving, and a quarter teaspoon of potassium chloride salt substitute carries several hundred milligrams. For anyone with reduced kidney function or taking an ACE inhibitor, ARB, spironolactone, eplerenone, amiloride, or trimethoprim, those sources can push potassium dangerously high.

Red flags: 99 mg "blood pressure support" pills sold as if they matter, and high-potassium electrolyte drinks used daily by people on potassium-sparing drugs. Green flags: a diet built on whole plant foods, and prescription potassium with lab follow-up when there is a deficit.

Products on Titrate

22,217 of the 214,745 labels in the NIH Dietary Supplement Label Database list potassium as an active ingredient (11,920 on market). 679 are sold as potassium products by name.

Top on-market labels, ranked by label completeness and simplicity:

1. Albion Complexed Potassium 99 mg Swanson Ultra · 99 mg as chelate
2. Reacted Magnesium & Potassium Ortho Molecular Products · 85 mg as glycinate
3. Potassium with Extend-Release Magnesium Life Extension · 99 mg as chloride
4. Potassium with Extend-Release Magnesium Life Extension · 99 mg as chloride
5. Ionic Potassium 50,000 PPM Good State · 50 mg as chloride

Open supplement search

Potassium does not have its own search category yet. Each product above links to its full label in the NIH database.

Related Tools

• Electrolyte Needs
• Potassium Chloride vs Potassium Citrate
• Potassium Chloride vs Potassium Gluconate
• Potassium Citrate vs Potassium Gluconate
• Potassium Bicarbonate vs Potassium Chloride
• Potassium Bicarbonate vs Potassium Citrate
• All potassium form comparisons
• All supplement guides

References

NIH Office of Dietary Supplements. Potassium: Fact Sheet for Health Professionals.

Cook NR, Obarzanek E, Cutler JA, et al. Joint effects of sodium and potassium intake on subsequent cardiovascular disease: the Trials of Hypertension Prevention follow-up study. Arch Intern Med. 2009;169(1):32-40.

Aburto NJ, Hanson S, Gutierrez H, Hooper L, Elliott P, Cappuccio FP. Effect of increased potassium intake on cardiovascular risk factors and disease: systematic review and meta-analyses. BMJ. 2013;346:f1378.

Neal B, Wu Y, Feng X, et al. Effect of salt substitution on cardiovascular events and death. N Engl J Med. 2021;385(12):1067-1077.