Low dietary sodium intake is associated with enhanced vascular endothelial function in middle-aged and older adults with elevated systolic blood pressure

Background: Age and increasing systolic blood pressure (BP) are associated with vascular endothelial dysfunction, but the factors involved are incompletely understood. We tested the hypothesis that vascular endothelial function is related to dietary sodium intake among middle-aged and older adults (MA and O) with elevated systolic BP. Methods: Data were analyzed on 25 otherwise healthy adults aged 48—73 years with high normal systolic BP or stage I systolic hypertension (130—159 mmHg). Self-reported sodium intake was <100 mmol/d in 12 (7 M) subjects (low sodium, 73±6 mmol/d) and between 100 and 200 mmol/d in 13 (9 M) subjects (normal sodium, 144±6 mmol/d). Results: Groups did not differ in other dietary factors, age, body weight and composition, BP, metabolic risk factors, physical activity and maximal aerobic capacity. Plasma concentrations of norepinephrine, endothelin-1, oxidized low-density lipoproteins (LDL), antioxidant status and inflammatory markers did not differ between groups. Brachial artery flow-mediated dilation (FMD) was 42% (mm Δ) to 52% (% Δ) higher in the low versus normal sodium group ( p < 0.05). In all subjects, brachial artery FMD was inversely related to dietary sodium intake (FMD mm Δr =—0.40, p < 0.05; %Δr =—0.53, p < 0.01). Brachial artery FMD was not related to any other variable. In contrast, endothelium-independent dilation did not differ between groups ( p ≥ 0.24) and was not related to sodium intake in the overall group ( p ≥ 0.29). Conclusions: Low sodium intake is associated with enhanced brachial artery FMD in MA and O with elevated systolic BP. These results suggest that dietary sodium restriction may be an effective intervention for improving vascular endothelial function in this high-risk group.