Dietary salt loading impairs arterial vascular reactivity.
BACKGROUND
Studies of sodium have shown improvements in vascular function and blood pressure (BP). The effect of chronic sodium loading from a low-sodium diet to a Western diet on vascular function and BP has been less well studied.


OBJECTIVE
The objective was to examine the effects of dietary salt intake on vascular function and BP.


METHODS
Thirty-five hypertensive volunteers met the inclusion criteria. After a 2-wk run-in with a low-sodium diet (60 mmol/d), the participants maintained their diets and were randomly assigned to receive sequentially 1 of 3 interventions for 4 wk, with a 2-wk washout between interventions: sodium-free tomato juice (A), tomato juice containing 90 mmol Na (B), and tomato juice containing 140 mmol Na (C). The outcomes were changes in pulse wave velocity (PWV), systolic BP (SBP), and diastolic BP (DBP).


RESULTS
The difference in PWV between interventions B and A was 0.39 m/s (95% CI: 0.18, 0.60 m/s; P < or = 0.001) and between C and A was 0.35 m/s (95% CI: 0.13, 0.57 m/s; P < or = 0.01). Differences in SBP and DBP between interventions B and A were 4.4 mm Hg (95% CI: 1.2, 7.8 mm Hg; P < or = 0.01) and 2.4 mm Hg (95% CI: 0.8, 4.1 mm Hg; P < or = 0.001), respectively, and between interventions C and A were 5.6 mm Hg (95% CI: 2.7, 8.4 mm Hg; P < or = 0.01) and 3.3 mm Hg (95% CI: 1.5, 5.0 mm Hg; P < or = 0.001), respectively. Changes in PWV correlated with changes in SBP (r = 0.52) and DBP (r = 0.58).


CONCLUSIONS
Dietary salt loading produced significant increases in PWV and BP in hypertensive volunteers. Correlations between BP and PWV suggest that salt loading may have a BP-independent effect on vascular wall function. This further supports the importance of dietary sodium restriction in the management of hypertension. This trial was registered with the Australian and New Zealand Clinical Trials Registry as ACTRN12609000161224.
Todd
Alwyn S
AS
Department of Medical & Surgical Sciences, University of Otago, Dunedin, New Zealand.
Macginley
Robert J
RJ
Schollum
John Bw
JB
Johnson
Richard J
RJ
Williams
Sheila M
SM
Sutherland
Wayne Hf
WH
Mann
Jim I
JI
Walker
Robert J
RJ
D000328:Adult; D001783:Blood Flow Velocity / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects*; D018592:Cross-Over Studies; D004039:Diet, Sodium-Restricted; D004730:Endothelium, Vascular / Q000187:drug effects*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000178:diet therapy / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D016037:Single-Blind Method; D017673:Sodium Chloride, Dietary / Q000494:pharmacology*
D017673:Sodium Chloride, Dietary