For people with slightly high blood pressure between 30 and 54 years old, how much salt they eat — measured by what shows up in their urine — doesn’t seem to clearly raise their risk of heart disease when looked at on its own.

If you're a middle-aged adult with slightly high blood pressure, having more sodium than potassium in your body may raise your chances of heart disease by 24% for every unit increase in the balance — and this combo predicts heart problems better than either mineral alone.

People aged 30 to 54 who eat more salt over several years are 12% more likely to die from any cause for every extra 1,000 mg of salt per day—and eating very little salt doesn’t seem to help them live longer.

If you're a middle-aged adult with slightly high blood pressure, peeing out more potassium might mean you have a lower chance of heart disease — one study found a 36% lower risk for those with the highest levels, but the result wasn't strong enough to be sure it wasn't just by chance.

If you have heart disease and eat more salt, your blood pressure tends to go up — for every extra gram of salt you excrete in urine, your top blood pressure number goes up by about 1.3 points and your bottom number by about 0.5 points.

For people who already have heart disease, eating just the right amount of salt — not too little and not too much — seems to be linked to the lowest chance of heart problems or dying from any cause. Too little or too much salt might actually be riskier.