The effect of dietary counseling on vascular function in high sodium consumers: a pilot study

Lennon-Edwards, ShannonCardiovascular disease is the leading cause of death in the United States. Research has shown that a low sodium diet is beneficial for cardiovascular health including endothelial health. High sodium intakes have been shown to diminish endothelial function while low sodium intakes have been associated with improved endothelial function. To date, much of this research has been done in a controlled feeding environment. While dietary counseling is a method that has been used to lower sodium intake to improve blood pressure, this approach has not been utilized to assess the impact of a low sodium diet on endothelial function in habitually high salt consumers who are free of hypertension and obesity. Therefore, the purpose of this study was to determine the effect of following a low sodium diet (2g/day) for 30 days on endothelial function in high sodium consumers (≥ 5g/day) independent of changes in blood pressure. Vascular function tests at baseline and 30 days were performed to determine brachial artery flow-mediated dilation, microvascular function, augmentation index (AIx) as assessed by pulse wave analysis, and carotid-to-femoral pulse wave velocity (PWV). Subjects underwent 24-hour blood pressure monitoring and collection of a 24-hour urine at baseline, midpoint, and 30 days. Subjects were counseled by a Registered Dietitian to achieve the 2g-sodium diet, and followed weekly to encourage compliance. Eight habitually high sodium consumers (6 M/2 F; age 35.3 ± 5.6 yrs) completed the dietary intervention study. All subjects were able to successfully lower their sodium intake from an average at baseline of 5284 ± 387 mg to an average of 1778 ± 409 mg at the fifth dietary recall (p0.05). This was confirmed by a non-significant decrease in urinary sodium excretion at day 30. Brachial artery FMD at baseline (7.29 ± 1.22%) and at day 30 (7.80 ± 1.5%) did not significantly differ over the 30-day period. When separating males from females, there was a trend toward significance between baseline and day 30 (p=0.13). Carotid-to-femoral PWV and AIx did not significantly differ over the thirty-day period. We did not see any significant changes in the nitric oxide mediated Plateau phase at the Ringer's site over the study intervention, or between the Ascorbic Acid site and Ringers, suggesting no improvements in microvascular function. In conclusion, dietary counseling to lower sodium intake in habitually high sodium consumers for 30 days resulted in lower dietary sodium intake levels, but did not significantly affect vascular function.University of Delaware, Department of Behavioral Health and NutritionM.S