Potassium
Also known as: K, Potassium citrate, Potassium chloride
The blood-pressure electrolyte — best obtained from food, with supplements legally capped at 99 mg per pill.
In short
Potassium is the body's main intracellular electrolyte, running nerve signals, muscle contractions (including every heartbeat), and blood pressure regulation. The evidence is striking from the food side: potassium-rich diets — fruits, vegetables, beans — reliably lower blood pressure, a cornerstone of the DASH diet. Supplements, by contrast, are deliberately capped at 99 mg per pill by US regulation, making pills nearly useless for correcting meaningful shortfalls.
- Main electrolyte inside cells: nerves, muscles, heartbeat
- High food potassium reliably lowers blood pressure (DASH diet)
- US supplements are capped at 99 mg per pill — trivial vs food
- Kidney disease turns potassium from safe to dangerous
What is Potassium?
Potassium is sodium's opposite number: where sodium raises blood pressure, potassium lowers it. Every cell pumps potassium in and sodium out, maintaining the electrical charge behind nerves and muscles — which is why both too little and too much potassium can stop a heart. The public-health message is food-based for good reason: the richest sources (bananas, potatoes, spinach, beans) deliver hundreds of milligrams, while supplement pills are capped at 99 mg each to prevent accidental overdose.
Where it comes from
Natural sources
- Potatoes, sweet potatoes, and bananas
- Spinach, avocados, and tomatoes
- Beans, lentils, and dried fruit
- Dairy, fish, and coconut water
How it's made
Supplemental potassium salts: chloride, citrate, gluconate — capped at 99 mg per serving in the US.
What it does in products
Benefits
Lowering blood pressure (from food)
strong evidenceThe DASH diet — rich in potassium foods — lowers blood pressure substantially, and potassium intake is inversely linked to stroke risk in cohort studies.
Preventing deficiency (hypokalemia)
strong evidenceDeficiency from diarrhea, vomiting, or diuretics is treated with prescription potassium — a medical scenario, not a supplement one.
Countering high-sodium diets
strong evidenceHigher potassium intake helps the kidneys excrete excess sodium, blunting salt's blood-pressure effect — the mechanism behind the food evidence.
Supplement pills for deficiency
moderate evidenceAt 99 mg per pill, OTC potassium is far too small to correct hypokalemia — prescription doses are needed. OTC pills suit only minor top-ups.
Side effects & safety
Safety considerations
- Adequate dietary potassium (2,900 mg daily in pregnancy) is recommended; supplements are rarely needed.
- ACE inhibitors, ARBs, and potassium-sparing diuretics raise potassium — never add supplements without medical guidance.
- NSAIDs can raise potassium levels.
- Not for: Chronic kidney disease (potassium accumulates dangerously)
- Not for: Heart failure with certain medications (monitor levels)
How it's used
In supplements
Aim for 2,600–3,400 mg daily from food (DASH-style intake). OTC pills provide 99 mg each and are only useful for minor gaps; meaningful deficiency requires prescription-strength potassium under medical supervision.
Regulatory status
- Dietary supplement under DSHEA, with a unique rule: the FDA limits OTC potassium to 99 mg per serving after reports of small-bowel injury from concentrated tablets. Prescription potassium is an FDA-approved drug.
- GRAS (generally recognized as safe) for food use.
Popular products containing Potassium
- Potassium Citrate 99 mgNOW Foods · Supplement
- Potassium Gluconate 99 mgNature Made · Supplement
- Electrolyte Powder with Potassium — Contains modest potassiumLiquid I.V. · Supplement
Product names and brands are shown for reference and belong to their respective owners.
Why food always beats potassium pills
The math makes the case. A baked potato delivers about 900 mg of potassium; a banana 420 mg; a cup of beans 600 mg. An OTC pill delivers 99 mg — you would need nine pills to match one potato, and the FDA cap exists precisely because concentrated potassium tablets can injure the gut. This is the rare supplement category where the food form is not just better but overwhelmingly so, and where 'more pills' is genuinely unsafe advice.
Frequently asked questions
How much potassium do I need per day?
Adequate intake is 3,400 mg for adult men and 2,600 mg for women. Most Americans fall short while simultaneously eating too much sodium — the double pattern behind the blood-pressure guidance.
Can potassium supplements be dangerous?
Yes, in the wrong hands. Excess potassium stops the heart, and the risk concentrates in kidney disease and certain medications. That is why OTC potassium is capped and real doses are prescription-only.
Which foods are highest in potassium?
Potatoes and sweet potatoes, spinach and beet greens, beans and lentils, bananas, avocados, tomatoes, and salmon. A DASH-pattern diet covers requirements without supplements.
The bottom line
Potassium is a blood-pressure powerhouse — from food. Eat potassium-rich foods generously, be cautious with salt, and leave potassium pills for the minor gaps they can actually fill. Anyone with kidney disease should treat potassium as a medication, not a supplement.
References
- Potassium — Health Professional Fact Sheet. NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional/
- Potassium and blood pressure (review). PubMed (National Library of Medicine). https://pubmed.ncbi.nlm.nih.gov/?term=potassium+blood+pressure+review
- Potassium compound summary. PubChem (National Library of Medicine). https://pubchem.ncbi.nlm.nih.gov/compound/5462222
- DASH diet and cardiovascular outcomes — literature search. PubMed (National Library of Medicine). https://pubmed.ncbi.nlm.nih.gov/?term=DASH+diet+blood+pressure+randomized