For people with heart disease, the more potassium their body gets rid of in urine, the higher their blood pressure tends to be — every extra gram of potassium excreted per day raises systolic pressure by about 1 point and diastolic by about 0.6 points, which is the opposite of what doctors usually expect.

For people who already have heart disease, the more potassium their body gets rid of in urine, the more likely they are to have a heart attack, stroke, or die — which is the opposite of what most people think potassium does.

For people who already have heart disease, having just the right balance of salt and potassium in their urine — not too much, not too little — seems to be linked to the lowest chance of heart problems or dying from any cause. Too little or too much of this balance is linked to higher risks.

People who pee out more potassium tend to have lower blood pressure, at least in adults between 20 and 59—but this isn’t true for everyone everywhere.

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.

When people pee out more salt than potassium, their blood pressure tends to be higher — it’s like the balance between salt and potassium in your urine tells you something about your blood pressure.