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James E. Brown1, Brett L. Cross1, Joseph D. Vondrasek1, Josiah M. Frederick1, Zoe R. Lincoln1, Peter Gaither1, Wesley T. Blumenburg1, Amy Chall1, Anna Bryan1, Ana Palacios1, Andrew A. Flatt1, Austin T. Robinson2, Gregory J. Grosicki1. 1Georgia Southern University (Armstrong Campus), Savannah, GA. 2Auburn University, Auburn, AL.

BACKGROUND: In America, Black adults are 30% more likely to die from cardiovascular disease than White adults. More than half of this racial health disparity can be attributed to greater prevalence of high blood pressure (BP) and vascular dysfunction in Black adults. Nitric oxide (NO) is a potent signaling molecule, key regulator of vascular health, and NO bioavailability is suspected to be lower in Black individuals. Therefore, we tested the hypothesis that increasing NO bioavailability via nitrate-rich beetroot juice (BRJ) would attenuate racial differences in BP and vascular health in Black compared to White adults. METHODS: We recruited 18 Black (10M/8F; 21±3 years; 24±3 kg/m2) and 20 White (10M/10F; 21±4 years; 23±3 kg/m2) young adults for a randomized, placebo-controlled, acute BRJ study. Central and peripheral BP and carotid-femoral pulse wave velocity (cf-PWV; an index of central arterial stiffness) were measured before and two hours after ingesting nitrate-rich BRJ (~12.8 mmol) and nitrate-deplete BRJ placebo (PLA), given in random order. Baseline cardiovascular measures were compared between visits (paired) and races (independent) t-tests. Post-supplementation cardiovascular measures were compared between races (i.e., Black vs. White) and treatment (i.e., BRJ vs. PLA) using linear mixed models. RESULTS: Compared to White participants, Black participants demonstrated greater baseline brachial diastolic (66±7 vs. 71±6mmHg; P=0.009), central systolic (100±8 vs. 107±10mmHg; P=0.028), and central diastolic BP (67±6 vs. 72±6mmHg; P=0.014). Brachial systolic BP (115±8 vs. 121±10mmHg; P=0.051) and cf-PWV (5.7±0.8 vs. 6.1±0.8m/s; P=0.075) were not statistically different in White vs. Black participants. Baseline BP and cf-PWV values were not different between BRJ and PLA visits (P≥0.288). Compared to PLA, post-BRJ supplementation brachial (-3.8mmHg; 95%CI: -6.6 to -1.1) and central systolic BP (-2.8mmHg; 95%CI: -5.1 to -0.5) were lower, but not other treatment effects were observed (P≥0.301). Significant main effects for race (P≤0.020) indicated that baseline differences in BP (i.e., higher in Black vs. White) remained post-supplementation. CONCLUSION: These data suggest that an acute nitrate-rich BRJ supplement lowers central and peripheral BP in young Black and White adults. However, acute BRJ supplementation does not appear to influence cf-PWV or attenuate racial differences in vascular health indices.

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