Dietary patterns and blood pressure

Lawrence J. Appel, et al.  A Clinical Trial of the Effects of Dietary Patterns on Blood Pressure, NEJM, 1997; 336:117-1124.

Compared to a control diet described as typical of the American diet, this 30-day controlled feeding trial demonstrated significant blood pressure falls for those with elevated blood pressure (inlcuding hypertensives).  Hypertensives, for example, decreased SBP by 11.4 mmHg, equivalent to taking two anti-hypertensive drugs.  Salt intake was held constant.

In 2001, a second trial, DASH-Sodium, found that those on the "DASH Diet" who also reduced their sodium intake by 60% to about 1,500 mg/day Na reduced their SBP by 11.5 mmHg.  NHLBI, which funded the study, declared this proof that salt reduction is an effective population intervention.  Subgroup analysis of the DASH-Sodium trial revealed that there was no statistically-significant BP effect of the severe salt reduction in six of the eight reported subgroups (no subgroup for overweight was reported).