Taking potassium supplements can lower your blood pressure, but only up to a point—around 30 mmol per day. After that, taking more doesn’t help much. The amount used in one study (20.6 mmol) was still in the range where more potassium equals more benefit.

If you don’t get enough potassium in your diet and start taking a supplement that adds about 20.6 mmol per day, your blood pressure might drop a little—roughly 3 points lower—according to studies that looked at multiple trials.

If you eat more potassium-rich foods, your blood pressure goes down in a straight-line way—more potassium means lower blood pressure, and this keeps happening all the way up to a pretty high amount, at least for people with high blood pressure.

If you eat more potassium every day—like from bananas or potatoes—your blood pressure might drop just a tiny bit, but not enough to matter for your health if you don’t already have high blood pressure.

If you eat more potassium-rich foods and less salty food, your blood pressure might drop by about 3.3 mmHg—and most of that drop probably comes from eating more potassium, not less salt.

If people eat less salt and more potassium-rich salt, the extra potassium might lower their blood pressure more than cutting back on salt alone — and most of that drop seems to come from the potassium.