Benefits
Healthy blood pressure support
In a meta-analysis of 23 randomized placebo-controlled trials (1,213 adults with high blood pressure), potassium supplements lowered systolic blood pressure by about 4.3 mmHg and diastolic by about 2.5 mmHg. A second meta-analysis of 15 trials in people not on blood-pressure drugs found similar drops, larger in those with high blood pressure.
Heart health when used as a salt substitute
In an open-label trial in 600 villages in rural China (20,995 adults with prior stroke, or aged 60 and over with high blood pressure), using a salt substitute of 75% sodium chloride and 25% potassium chloride for about 4.7 years was followed by fewer strokes and major cardiovascular events than regular salt, without more serious high-potassium events.
Rehydration after exercise-induced fluid loss
In a small study of 8 healthy men dehydrated by about 2% of body weight, a drink containing 25 mmol/L potassium chloride was retained better than a glucose-only drink, about as well as salt or mixed-electrolyte drinks, leaving them in a smaller fluid deficit the next morning. This is a single small crossover experiment.
Meeting the daily Adequate Intake
Adult Adequate Intakes are 3,400 mg of potassium a day for men and 2,600 mg for women, and most people in the United States get less than this. Most potassium supplements provide no more than 99 mg per serving, so food and potassium chloride salt substitutes contribute far more. Correcting a diagnosed low blood potassium is a medical treatment that needs supervision.
Mechanism of action
Sodium and potassium balance
Raising potassium intake while lowering sodium shifts the urinary sodium-to-potassium ratio; in a meta-analysis of supplement trials, greater potassium excretion and a lower sodium-to-potassium ratio tracked with larger blood-pressure reductions.
Cell membrane gradients
Potassium is the most abundant cation inside cells, about 30 times more concentrated than outside. The gradient, maintained by the sodium-potassium pump, is needed for nerve transmission, muscle contraction, kidney function and cell fluid volume.
Kidney control of potassium
The kidneys excrete most excess potassium. When kidney function is impaired, or with drugs that reduce potassium excretion, extra potassium can accumulate and cause high blood potassium.
Clinical trials
Open-label cluster-randomized trial in 600 villages comparing a salt substitute (75% sodium chloride, 25% potassium chloride) with regular salt, mean follow-up 4.74 years (Neal et al. 2021, N Engl J Med).
20,995 adults in rural China with a history of stroke, or aged 60 or older with high blood pressure.
Stroke rates were lower with the salt substitute (29.14 versus 33.65 per 1,000 person-years; rate ratio 0.86), as were major cardiovascular events (rate ratio 0.87) and deaths (rate ratio 0.88). Serious adverse events attributed to high potassium did not differ significantly (rate ratio 1.04).
Meta-analysis of randomized placebo-controlled trials of oral potassium supplementation for at least 4 weeks (Poorolajal et al. 2017, PLoS One).
23 trials, 1,213 adults with essential hypertension.
Potassium supplementation lowered systolic blood pressure by 4.25 mmHg and diastolic by 2.53 mmHg versus placebo, with moderate heterogeneity.
Meta-analysis and meta-regression of randomized trials of potassium supplementation in people not taking blood-pressure medication (Binia et al. 2015, J Hypertens).
15 trials, 917 participants.
Potassium supplementation lowered systolic blood pressure by 4.7 mmHg and diastolic by 3.5 mmHg overall, and by 6.8 and 4.6 mmHg in people with hypertension; larger reductions tracked with higher urinary potassium and a lower sodium-to-potassium ratio.
Randomized-order crossover study of four rehydration drinks (glucose, sodium chloride, potassium chloride, or all three) after exercise dehydration (Maughan et al. 1994, Eur J Appl Physiol Occup Physiol).
8 healthy men dehydrated by about 2% of body mass.
Urine output was higher after the glucose-only drink than after any electrolyte drink, and the next morning net fluid deficit was larger with glucose (745 mL) than with sodium chloride (405 mL), potassium chloride (467 mL) or the mixed drink (407 mL); the three electrolyte drinks did not differ.