Does a high salt/high calcium diet improve blood pressure and renal blood flow responses compared to a high salt/low calcium diet in hypertensive patients?
A low calcium diet exacerbates salt-sensitive blood pressure increases and blunts compensatory renal blood flow responses in hypertensive patients.
This study was designed to determine the interaction between salt and calcium intake on blood pressure (BP) and renal blood flow (RBF) in a predominantly white population. We measured BP and RBF (P-aminohippurate PAH clearance) in hypertensive patients after 7 days on a low salt/low calcium diet and again after either a high salt/high calcium diet (HS/HC) or a high salt/low calcium (HS/LC) diet for another 7 days. Compared to low salt BP, both high salt diets increased BP, but the increase with high salt/low calcium was significantly greater than with high salt/high calcium (+14.6 +/- 3.9/+8.2 +/- 1.7 mm Hg v +7.5 +/- 1.9/+2.5 +/- 1.4 mm Hg; systolic/diastolic, both P less than or equal to .05). PAH clearance increased 26 +/- 13 mL/min/1.73 m2 on the HS/HC diet but only 10 +/- 17 mL/min/1.73 m2 on HS/LC (P = .05 between groups). These data suggest that a low calcium diet may contribute to the phenomenon of salt sensitivity in a white population. The low calcium intake appears to affect both the systemic and renal vasculature.
Rich et al. (Fri,) studied this question.