What it's actually good for
Potassium is an electrolyte your body needs for nerve signaling, muscle contraction, and fluid balance, and most Americans don't eat enough of it — the shortfall between typical intake and the 2019 Adequate Intake (3,400 mg/day for men, 2,600 mg/day for women) is real and well documented. The interesting evidence isn't about deficiency symptoms, though; it's about blood pressure. A 2020 dose-response meta-analysis in the Journal of the American Heart Association pooled 32 randomized trials and found that increasing potassium intake measurably lowers blood pressure, with the biggest effect in people who already have hypertension and eat a lot of sodium.
The catch, and it's a significant one for a supplement page: the trials that show this effect used 30-140 mmol/day of potassium — roughly 1,170 to 5,460 mg of elemental potassium daily, mostly as potassium chloride. A standard over-the-counter potassium supplement in the U.S. delivers 99 mg per pill, capped by industry convention because higher-dose potassium chloride tablets have been linked to small-bowel injury and dangerous spikes in blood potassium. That's roughly 1-8% of the dose that moved the needle in the research. This product genuinely helps close a dietary gap; it is not a way to replicate a clinical-trial blood-pressure effect.
What the research says
Blood pressure (Grade B). The JAHA meta-analysis found a U-shaped dose-response relationship: benefit increased with potassium intake up to about a 30 mmol/day difference between groups, then plateaued, and reversed into a blood-pressure increase above roughly 80 mmol/day — particularly in people taking antihypertensive medication. This is a genuinely useful finding for how much dietary potassium to aim for, and it's graded B rather than A specifically because the trial doses don't map onto an OTC supplement dose. If you're relying on a 99 mg pill to move your blood pressure the way these trials did, it won't.
Stroke risk (Grade B). Observational cohorts summarized by the NIH cite roughly a 21% lower stroke risk associated with diets higher in potassium by about 1,640 mg/day. This is association, not supplementation trial data, and people who eat more potassium-rich food (vegetables, legumes, fruit) tend to differ from those who don't in other ways that also affect stroke risk.
How much, and which form
OTC potassium supplements are capped at 99 mg per dose in the U.S. — that's the number you'll see on every mainstream bottle, regardless of brand. It's a small, incremental top-up, not a way to hit the doses used in the BP trials. If your goal is the dietary intake associated with cardiovascular benefit, food does the actual work: potatoes, beans, leafy greens, yogurt, and bananas all contribute meaningfully more potassium per serving than a supplement pill does. Potassium citrate and gluconate are the common OTC forms and tend to be gentler on the stomach than chloride at equivalent low doses; at 99 mg, the difference between forms is minor.
Safety & interactions
This is the section that matters most for potassium. In people with normal kidney function, 99 mg doses are low-risk. In people with chronic kidney disease, the calculus changes fast — a 2022 open-label study (a single-arm run-in phase of a larger trial, not a randomized comparison) found that even a two-week course of moderate-dose potassium chloride (40 mmol/day, well above the OTC cap) pushed 11% of CKD patients into hyperkalemia, a condition that can cause fatal heart arrhythmias. ACE inhibitors, ARBs, and potassium-sparing diuretics all raise this risk further by reducing how much potassium the kidneys clear. If you have any degree of kidney impairment or take blood-pressure medication, talk to a clinician before adding a potassium supplement — this is informational content, not medical advice.
How we picked the brand
A potassium supplement earns a spot when it labels elemental potassium clearly at the standard 99 mg OTC dose, uses citrate or gluconate (gentler on the gut than chloride at this dose), comes from a GMP-certified, independently tested manufacturer, and skips proprietary blends or unnecessary fillers.