Objective: To investigate the hemodynamic effects of a moderately low-salt diet in a 9-week, randomized, double-blind, crossover study in 20 hypertensive, ambulatory patients.
Methods: All subjects followed a 9-week, low-salt diet. During this period, they received capsules containing either lactose or salt in 4-week treatment periods, separated by a 1-week washout period. Hemodynamic and biological parameters were evaluated on the day of randomization and at the end of weeks 4 and 9. We defined a low-sodium diet (LSD) as a salt-restriction period with lactose capsules, and a normal-sodium diet (NSD) as a salt-restriction period with capsular salt supplementation.
Results: Blood pressure was significantly lower during LSD compared with NSD. This fall in blood pressure was associated with a decrease in peripheral resistance in carotid and forearm circulation. Brachial artery diameter was larger during LSD whereas carotid artery diameter remained unchanged. The changes in brachial artery were: (1) not related to blood pressure changes; (2) positively related to age, and (3) negatively correlated with baseline intracellular sodium content.
Conclusions: These results suggest that moderate low-salt restriction is capable of decreasing blood pressure and peripheral resistance in carotid and forearm circulation. The increase in brachial, but not carotid, artery diameter following salt restriction suggests a difference in salt dependence among different arteries.