Highlights
- •A diet containing 9 g salt/day impaired flow mediated dilatation (FMD) and increased endothelin-1.
- •A 3 g reduction in salt intake reversed the impaired FMD and improved serum endothelin-1.
- •Asymmetric dimethylarginine, plasma and urinary nitrate/nitrite concentrations did not change.
- •Aldosterone and renin were unchanged by salt reduction.
Abstract
Background and aim
It is unclear if a modest reduction in dietary salt intake has beneficial effects
on vascular function. The aim was to compare the effects of 9 g salt/day with 6 g
salt/day intake on measures of vascular function and explore mechanisms of effect
in overweight and obese adults.
Methods
Twenty-five overweight/obese subjects (BMI 27–40 kg/m2) completed a randomised cross-over study of 6 weeks each on a reduced salt (RS) (6 g/day)
and usual salt diet (US) (9 g/day). Flow-mediated-dilatation (FMD), 24 h blood pressure
(BP), augmentation index (AIx), pulse wave velocity (PWV), plasma and urinary nitrate/nitrite,
asymmetric dimethylarginine (ADMA), renin, aldosterone and endothelin-1 and vascular
adhesion molecules were measured after 2 days and 6 weeks. Adherence to the diets
was determined from two 24 h urine collections.
Results
Urinary sodium excretion was 155 ± 58 mmol/24 h US vs 113 ± 45 mmol/24 h RS (p = 0.002). Following the RS diet there was a significant improvement in FMD from 3.5 ± 2.8%
to 5.6 ± 2.8% (P < 0.001) and decrease in serum endothelin-1 from 1.45 ± 0.38 pg/ml to 1.25 ± 0.39 pg/ml
(P < 0.05). Endothelium-independent vasodilatation was also significantly different
between treatments (P < 0.05). AIx, PWV, serum ADMA and plasma and urinary nitrate/nitrite concentrations
were not different between treatments. Change in FMD was related to the urinary sodium:
creatinine ratio (r = −0.47, P < 0.05) and was independent of blood pressure. Aldosterone and renin were unchanged.
Conclusions
A small reduction in dietary salt intake of 3 g/day improves endothelial function
in normotensive overweight and obese subjects. This response may be mediated by serum
endothelin-1. This small reduction in salt had no effect on aldosterone and renin
concentrations.
This trial was registered with the Australian and New Zealand Clinical Trials Registry
Unique Identifier: ACTRN12609000321246 http://www.anzctr.org.au/ACTRN12609000321246.aspx
Keywords
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Article Info
Publication History
Accepted:
November 22,
2013
Received in revised form:
November 6,
2013
Received:
September 17,
2013
Identification
Copyright
© 2014 Elsevier Ireland Ltd. Published by Elsevier Inc. All rights reserved.
