Salt and blood pressure in community-based intervention trials

This article reviews community-based salt intervention trials. In the Belgian Salt Intervention Trial, a controlled 5-y intervention in two Belgian towns resulted in a reduction in urinary sodium of 17 mmol/24 h (P < 0.001) in adult (aged > or = 20 y) women in the intervention town, which differed from the concurrent trend (an increase of 8 mmol/24 h) in the control town (P = 0.01). However, both systolic (-7.5 compared with -7.9 mm Hg) and diastolic (-2.3 compared with -3.0 mm Hg) pressures declined to the same extent in women of the two towns. In adult men in the intervention town, decreases were observed in urinary sodium (-12 mmol/24 h) and in systolic (-5.6 mm Hg) and diastolic (-2.4 mm Hg) blood pressures, but these trends were the same in the control town (-12 mmol/24 h, -4.9 mm Hg, and 0.2 mm Hg, respectively). The Belgian study and the four other community-based salt intervention trials reviewed show that, in general, salt intake in the long-run cannot be restricted below 5 g/24 h. More moderate salt restriction may constitute a more realistic goal, but its influence on blood pressure in the community at large is probably trivial.