How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Potassium
A mineral whose higher intake lowers blood pressure, especially if your diet is high in salt. Trial doses are high and require caution with certain medications.
Benefits
- Lowers blood pressure in hypertensives: −4.5 mmHg systolic and −3.0 mmHg diastolic on average (meta-analysis), more so when the diet is salty and low in potassium, and in those not taking treatment
- In untreated people with borderline or high pressure, 3 g of potassium per day for 4 weeks lowered 24-hour pressure by 3.9/1.6 mmHg; in 87 people with a low-potassium diet, 80 mmol per day for 21 days lowered it by 6.9/2.5 mmHg compared to placebo
- Even with normal pressure, an intake of 60 mmol per day at most, over more than a month, lowers systolic pressure by 2.3 to 2.8 mmHg (meta-analysis)
- Replacing table salt with a potassium-enriched salt (25% potassium chloride) reduced strokes, major cardiovascular events, and all-cause deaths in 20,995 at-risk individuals, without more severe excess potassium accidents; in elderly participants with normal pressure, it slowed the onset of hypertension (−8.0 mmHg systolic)
Precautions
Too much potassium in the blood can be serious: a case of life-threatening hyperkalemia, with kidney failure, is described in an elderly person who was taking potassium supplements with an antihypertensive of the ACE inhibitor family (captopril) and a diuretic (furosemide). If you are taking antihypertensives or diuretics, or if your kidneys are not working properly, do not take any without medical advice and monitoring of your blood potassium levels. Wax-matrix potassium chloride tablets caused stomach lesions within a week in healthy volunteers, without any symptoms. In 100 hypertensive patients on a thiazide diuretic, 40 mmol per day for 24 weeks did not correct blood sugar disorders and worsened uric acid disorders. Beyond 80 mmol per day more, a meta-analysis sees pressure potentially rise again. The limitations: the 2006 Cochrane review of six trials in hypertensives did not find a significant drop; in 21 healthy people, 100 mmol per day did not change pressure; the drop in strokes and deaths comes from a salt substitute used in China by at-risk individuals, not from capsules, and the detailed cardiac analyses are a posteriori; after cardiac surgery, supplementing to keep potassium high did not better prevent atrial fibrillation in 1,690 patients.
Recommended dosage
Trials have tested from 40 to 100 mmol of potassium per day (approximately 1.6 to 3.9 g), most often 60 to 80 mmol, for 1 to 24 weeks. A dose-response meta-analysis sees the effect on pressure weaken beyond 30 mmol per day more than the control group; in individuals with normal pressure, 60 mmol per day at most over more than a month yield the greatest drop. Potassium citrate lowers pressure as much as chloride.
Did you know?
Wax-matrix potassium chloride tablets caused stomach lesions within a week in healthy volunteers, without the slightest digestive symptom.
What the studies say
This meta-analysis sought to determine the optimal dose and duration of magnesium and potassium supplementation to reduce systolic blood pressure in normotensive individuals. For potassium, dosages of ≤60 mmol/day and treatment durations greater than one month showed the greatest reductions. Potassium supplementation under these conditions decreased systolic blood pressure by 2.34 mmHg at low dosages and by 2.80 mmHg over longer durations. The study suggests that lower dosages and longer treatments could be more effective for the general population.
Behers BJ, Behers BM, Stephenson-Moe CA, Vargas IA, Meng Z, Thompson AJ, Melchor J, Wojtas CN, Rosario MA, Baker JF, Deevers AC, Mouratidis RW, Sweeney MJ. — Nutrients (2024) — View the source study
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more