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Potassium

Raising potassium intake lowers blood pressure, and in the one large hard-outcome trial it reduced stroke and death. The catch: the evidence is for potassium from food and salt substitutes, and over-the-counter potassium pills are legally capped at doses far too small to matter.

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What the science says

  • Lowers blood pressure, dramatically so in hypertensives Strong evidence

    A meta-analysis of 22 RCTs (1,606 participants) found increased potassium intake reduced systolic blood pressure by 3.49 mmHg (95% CI 1.82-5.15) overall, and by 7.16 mmHg (95% CI 1.91-12.41) in hypertensive participants at intakes of 90-120 mmol/day, with no further gain above that. An earlier JAMA meta-analysis found a comparable effect (-3.11 mmHg systolic, -1.97 diastolic), largest in people with high sodium intake.

  • Reduces stroke and death when delivered as a salt substitute Strong evidence

    SSaSS randomised 20,995 rural Chinese adults with prior stroke or aged 60+ with hypertension to a 75% sodium chloride / 25% potassium chloride salt substitute or regular salt for about five years. Stroke fell (29.14 versus 33.65 events per 1,000 person-years; rate ratio 0.86, 95% CI 0.77-0.96), as did major cardiovascular events (0.87, 0.80-0.94) and all-cause death (0.88, 0.82-0.94), with no excess of serious hyperkalaemia (rate ratio 1.04).

  • Cohort data agree, and higher intake is not hard on healthy kidneys Moderate evidence

    Pooled cohort data show higher potassium intake associated with roughly 24% lower stroke risk (RR 0.76, 95% CI 0.66-0.89), consistent in direction and size with the trial evidence. The same review found increased potassium intake had no adverse effect on renal function, blood lipids or catecholamine concentrations in people with normal kidneys — which supports blood pressure as the mechanism.

Dosage & safety

Studied doseAdequate intake is 3,400 mg/day for men and 2,600 mg/day for women; most adults get 2,000-2,500 mg. The trial-effective range is roughly 90-120 mmol/day (3,500-4,700 mg). Over-the-counter potassium supplements in the US are limited to 99 mg per tablet — about 3% of daily needs — so pills are close to useless for this purpose. The routes that actually work are potassium chloride salt substitutes (roughly 300-400 mg potassium per gram) and food: beans, potatoes, leafy greens, tomato products, yoghurt, bananas.
SafetyThe entire risk profile is hyperkalaemia, and it is dose- and kidney-dependent. Potassium supplements and salt substitutes are dangerous in chronic kidney disease (roughly eGFR below 45-60) and in anyone taking ACE inhibitors, ARBs, aldosterone antagonists (spironolactone, eplerenone), potassium-sparing diuretics, NSAIDs, trimethoprim or heparin — these were exclusion criteria or explicit cautions in the trials. Untreated Addison's disease is a contraindication. Solid potassium chloride tablets can cause gastrointestinal ulceration and stricture; wax-matrix and effervescent formulations reduce this. Anyone in the above groups should have serum potassium and kidney function checked before increasing intake, and should not adopt a salt substitute casually.

How to take it

TimingTiming does not matter.
With food?With food and a full glass of water — solid potassium chloride tablets can ulcerate the gut lining when they sit against it.
Worth knowingOver-the-counter 99 mg tablets are about 3% of a day's needs and are close to useless; food and potassium-chloride salt substitute are the only routes that move the number.

Interactions

With medications

  • ACE inhibitors and ARBs (ramipril, lisinopril, losartan)

    These drugs raise blood potassium on their own; added potassium can cause dangerous hyperkalaemia. do not use potassium supplements or salt substitutes without a potassium and kidney function check

  • aldosterone antagonists and potassium-sparing diuretics (spironolactone, eplerenone, amiloride)

    The strongest potassium-retaining drugs there are; combining them with supplemental potassium is a recognised cause of life-threatening hyperkalaemia. do not combine without explicit medical supervision and blood monitoring

  • NSAIDs, trimethoprim and heparin

    All reduce potassium excretion, which is easy to overlook because none are thought of as potassium drugs. be cautious with salt substitutes while taking them, especially with reduced kidney function

  • digoxin

    Both low and high potassium alter digoxin toxicity and arrhythmia risk. do not change potassium intake substantially without monitoring

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does potassium lower blood pressure?

Yes — the evidence is strong. A meta-analysis of 22 trials found higher potassium intake lowered systolic pressure by 3.49 mmHg overall and by 7.16 mmHg in people with hypertension at intakes of 90–120 mmol/day.

Are over-the-counter potassium pills worth taking?

Not really. US over-the-counter potassium tablets are capped at 99 mg, about 3% of daily needs, so the routes that actually raise potassium are food and potassium chloride salt substitutes.

Does a potassium salt substitute reduce stroke risk?

Yes, with strong evidence: the SSaSS trial in 20,995 older or stroke-affected adults found a 25% potassium chloride salt substitute reduced stroke, major cardiovascular events and death over about five years.

Is potassium safe with blood pressure medication?

Not without checks. ACE inhibitors, ARBs, spironolactone and other potassium-sparing drugs raise blood potassium, and adding potassium or a salt substitute can cause dangerous hyperkalaemia, as can kidney disease.

Scientific references

Where to buy

Alta Health, Potassium Chloride plus Silica, 100 Capsules

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