In a large study in 18 countries, sodium and potassium intake were estimated from urine samples and correlated with blood pressure. The correlations were nonlinear and were most pronounced among people with high sodium intake, those with hypertension, and older persons. Hypertension affects 1 billion people and is considered to be a leading cause of death, stroke, myocardial infarction, congestive heart failure, and chronic renal impairment. 1 – 4 Sodium intake is reported to be a modifiable determinant of hypertension. 5 , 6 The International Study of Salt and Blood Pressure (INTERSALT), 7 but not another large study, 8 showed a modest association between higher levels of sodium intake and higher blood pressure. However, INTERSALT was not large enough to determine whether the association varied according to region, participant characteristics, or levels of sodium or potassium intake. Substantially larger studies are needed to assess the shape of . . .