Abstract P172: Dietary Sodium-to-Fiber Ratio Is Independently Associated With Body Composition And Blood Pressure In Healthy Adults

Background: High dietary sodium (Na + ) is associated with poorer body composition, increased blood pressure (BP), and decreased vascular function, whereas high dietary fiber typically has opposing associations. However, it is unknown whether dietary Na + indexed to fiber ( i.e., Na + /Fiber) is an independent predictor of body composition and cardiovascular health. Therefore, we examined relations between Na + /Fiber, body composition, BP, and vascular function. Methods: We assessed body composition using body mass index (BMI) and waist:hip ratio, brachial BP via oscillometry, arterial stiffness via carotid-femoral pulse wave velocity (cf-PWV), and endothelial function via brachial artery flow-mediated dilation (FMD). Participants (n=50; 22 Male/28 Female, 35±16 years, BMI: 27±4 kg/m 2 , BP 116±11/70±7 mmHg, mean±SD) completed 3-day food and fluid logs to derive daily Na + and fiber intake. We used unadjusted and covariate-adjusted Pearson’s correlations to assess relations between Na + /Fiber and physiological outcomes. We used ANCOVA to compare physiological outcomes between tertiles of Na + /Fiber ratio. Covariates included age, sex, race, and dietary potassium. Results: In unadjusted models, Na + /Fiber was correlated with BMI (r = 0.444, p = 0.001), waist:hip ratio (r = 0.320, p = 0.023), brachial systolic (r = 0.316, p = 0.026), and diastolic BP (r = 0.321, p = 0.023), but not cf-PWV (r = 0.126, p = 0.383) or FMD (r = 0.120, p = 0.408). With covariate adjustment, Na + /Fiber remained correlated with BMI (r = 0.417, p = 0.004), waist:hip ratio (r = 0.438, p = 0.002), and systolic BP (r = 0.297, p = 0.045). Using ANCOVA, there was an effect of Na + /Fiber on BMI and waist:hip ratio ( ps < 0.021). There was also an effect of Na + /Fiber on systolic BP (overall p = 0.014; high: 123±3 mmHg, middle: 114±3 mmHg, low: 113±3 mmHg), with significant post hoc differences between the high and middle tertiles ( p = 0.029) and the high and low tertiles ( p = 0.038). Importantly, dietary Na + /Fiber more strongly associated with BMI, waist:hip ratio, and BP than Na + and fiber alone. Conclusion: Our preliminary data indicate that Na + /Fiber ratio is an independent predictor of poorer body composition and increased blood pressure in healthy adults.