Intersalt: Sodium excretion and blood pressure

Intersalt Cooperative Research Group.  Intersalt: an international study of electrolyte excretion and blood pressure. Results for 24 hour urinary sodium and potassium excretion.  BMJ. 1988 July 30; 297(6644): 319–328.

This study was funded by the National Heart, Lung and Blood Institute (NHLBI) and numerous other national health agencies, conducted in the mid-1980s in 52 centers in 32 countries and designed as the definitive study of the question of the primary hypothesis:  does sodium excretion (i.e. sodium intake) predict blood pressure.  The results disappointed the sponsors because they showed no relationship between population sodium intakes and population blood pressures.  Not content with this finding, the authors published an analysis showing that older subjects had higher blood pressures and postulated that salt caused a BP "rise with age" although this was a "snapshot" of a single point in time, not a study of any group over time.