Zach J. Hutchison1, Braxton A. Linder1, McKenna A. Tharpe1, Alex M. Barnett1, Meral N. Culver1, Sofia O. Sanchez1, Soolim Jeong1, Joseph C. Watso2, Gregory J. Grosicki3, Austin T. Robinson1. 1Auburn University, Auburn, AL. 2Florida State University, Tallahassee, FL. 3Georgia Southern University, Savannah, GA.

Background: High dietary sodium (Na+) increases blood pressure (BP) and decreases vascular function, whereas high dietary fiber is associated with reduced BP. However, the combined effect of dietary Na+ and fiber on BP and vascular function is unclear. Therefore, we assessed dietary Na+ indexed to fiber (Na+/Fiber) and soluble fiber (Na+/Sol Fiber) intake in healthy young adults. Methods: Forty-six young adults (24 Male/22 Female, 21.0 ± 0.7 years, body mass index: 25 ± 3 kg/m2, BP 117 ± 9/69 ± 9 mmHg, mean ± SD) were included in this analysis. We assessed brachial BP and carotid-femoral pulse wave velocity (cf-PWV; an index of arterial stiffness) using SphygmoCor XCEL. In a subset of 40 participants, we assessed brachial artery flow-mediated dilation (FMD; Arietta 70 vascular ultrasound). Participants completed a food and fluid log for ≥2 weekdays and ≥1 weekend day. We used Nutrition Data System for Research to quantify average daily dietary Na+, total fiber, and soluble fiber. We analyzed the association between variables using simple linear regression and ANOVA (to compare tertiles of Na+/Fiber or Na+/Sol Fiber). Results: There was not an association between BP and Na+/Fiber (systolic BP: R2 = 0.046, p = 0.150, diastolic BP: R2 = 0.061, p = 0.097), but there was between BP and Na+/Sol Fiber (systolic BP: R2 = 0.080, p = 0.056, diastolic BP: R2 = 0.113, p = 0.022). When participants were split into tertiles by Na+/Fiber and Na+/Sol Fiber, we detected differences in diastolic BP (ps < 0.043) but not systolic BP (ps ≥ 0.097). Participants’ cf-PWV was associated with Na+/Fiber (R2 = 0.152, p = 0.001) and Na+/Sol Fiber (R2 = 0.116, p = 0.007), but we did not detect tertile differences in cf-PWV for either Na+/Fiber or Na+/Sol Fiber (ps ≥ 0.128). Neither Na+/Fiber nor Na+/Sol Fiber were associated with FMD and there were no differences in FMD among tertile groups (ps ≥ 0.149). Conclusion: While additional data are needed, our data in healthy young adults indicate that dietary sodium indexed to soluble fiber is associated with increased blood pressure and arterial stiffness but is not related to peripheral vascular endothelial function.

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