Benefits
Supports healthy blood pressure at food-level intakes
In a meta-analysis of 22 randomized trials in 1,606 people, raising potassium intake lowered systolic blood pressure by about 3.5 mmHg and diastolic by about 2.0 mmHg. The effect was seen in people with high blood pressure but not in people with normal readings. The trials raised intake by gram amounts, far above the 99 mg in most potassium supplements, so this supports potassium-rich food rather than a pill.
Potassium-enriched salt substitute: a large outcome trial
In about 21,000 adults in rural China who had a past stroke, or were 60 or older with high blood pressure, villages that swapped regular salt for one that was 25% potassium chloride had fewer strokes (rate ratio 0.86), fewer major cardiovascular events and fewer deaths over about 4.7 years. This tested a cooking salt swap in high-risk people, not a supplement.
Potassium and urine chemistry
According to the NIH Office of Dietary Supplements, low potassium intake can raise urinary calcium excretion and kidney stone risk. Prescription potassium citrate, given at gram-level doses with monitoring, is a drug rather than a dietary supplement, and none of the studies cited on this page tested kidney stones. Recurrent kidney stones are a medical condition to manage with a doctor.
Potassium and normal muscle function
Potassium is needed for muscle cells to reset after each contraction. Low blood potassium (hypokalemia) causes muscle weakness, cramps and fatigue, but it is usually driven by diuretics, vomiting or diarrhea rather than ordinary eating, because healthy kidneys conserve potassium well. No study cited on this page tested potassium for exercise cramps, and cramping has many causes.
Fluid balance and electrolyte support
As the main mineral inside cells, potassium pairs with sodium outside cells to keep cell volume, nerve signaling and muscle function in balance. The kidneys excrete most potassium, some leaves in stool, and only a very small amount is lost in sweat. These are physiology points, not trial results: none of the studies cited on this page looked at hydration or exercise.
Average intakes fall below the recommended amount
US adults average about 3,016 mg of potassium a day from food (men) and 2,320 mg (women), below the Adequate Intakes of 3,400 and 2,600 mg. Good sources per serving include cooked lentils (731 mg per cup), canned kidney beans (607 mg per cup), a baked potato without the skin (610 mg), a banana (422 mg) and farmed salmon (326 mg per 3 oz). A 99 mg supplement adds little by comparison.
Mechanism of action
Sodium-potassium pump
The sodium-potassium pump (Na+/K+-ATPase) keeps potassium concentrated inside cells and sodium outside. That gradient sets the resting electrical charge of nerve and muscle cells, which is the basis of nerve signaling and muscle contraction.
Kidney sodium excretion
Higher potassium intake helps the kidneys excrete more sodium, which is one leading explanation for its effect on blood pressure. In the DASH-Sodium trial the lowest readings came from combining a potassium-rich eating pattern with lower sodium, again as whole diets rather than pills.
Blood vessel relaxation
Potassium can relax the smooth muscle in blood vessel walls, which may lower resistance to blood flow. This is thought to work alongside the kidney effect, but it has not been measured in the trials cited on this page.
Urinary alkalinization
Potassium citrate makes urine less acidic and lowers urinary calcium, the rationale behind prescription potassium citrate for people who repeatedly form kidney stones. The idea that fruit- and vegetable-rich diets spare bone for the same reason remains unproven and is not tested by any study cited here.
Clinical trials
Open-label cluster-randomized trial in 600 villages in rural China comparing a salt substitute (75% sodium chloride, 25% potassium chloride) with regular salt for cooking, mean follow-up 4.74 years. A salt swap, not a potassium supplement (Neal et al. 2021, N Engl J Med)
20,995 adults with a history of stroke, or aged 60 or older with high blood pressure; mean age 65.4, 72.6% with a past stroke.
Stroke rate was 29.14 versus 33.65 events per 1,000 person-years (rate ratio 0.86, 95% CI 0.77 to 0.96). Major cardiovascular events (rate ratio 0.87) and deaths (0.88) were also lower. Serious adverse events attributed to high blood potassium did not differ (3.35 versus 3.30 per 1,000 person-years). People with kidney disease or on potassium-retaining medicines should not copy this without medical advice.
Systematic review and meta-analyses of 22 randomized trials reporting blood pressure and other risk factors, plus 11 cohort studies reporting disease outcomes (Aburto et al. 2013, BMJ)
1,606 participants in the randomized trials; 127,038 in the cohort studies.
Higher potassium intake lowered systolic blood pressure by 3.49 mmHg (95% CI 1.82 to 5.15) and diastolic by 1.96 mmHg, an effect seen in people with hypertension but not in those without. There was no significant adverse effect on kidney function, blood lipids or catecholamines. In the cohort studies, higher intake was associated with a 24% lower stroke risk, an observational link rather than a trial result.
Meta-analysis of 33 randomized trials in which potassium supplementation was the only difference between groups (Whelton et al. 1997, JAMA)
2,609 participants in trials published before July 1995.
After one trial with an extreme result was excluded, potassium supplementation lowered systolic blood pressure by 3.11 mmHg and diastolic by 1.97 mmHg. The effect appeared larger in trials where participants also ate a lot of sodium.
Randomized controlled feeding trial: after a 3-week run-in, participants ate a control diet, a fruit-and-vegetable diet or a combination diet also rich in low-fat dairy for 8 weeks, with sodium and weight held constant. A whole-diet trial, not a potassium supplement (Appel et al. 1997, N Engl J Med)
459 adults with systolic blood pressure under 160 mmHg and diastolic 80 to 95 mmHg; 133 had hypertension.
The combination diet lowered systolic and diastolic blood pressure by 5.5 and 3.0 mmHg more than the control diet; in participants with hypertension the differences were 11.4 and 5.5 mmHg. These results belong to the whole eating pattern and cannot be credited to potassium alone.