Influence of dietary nitrate food forms on nitrate metabolism and blood pressure in healthy normotensive adults.

Inorganic nitrate (NO) supplementation has been shown to improve cardiovascular health indices in healthy adults. The purpose of this study was to investigate how the vehicle of NO administration can influence NO metabolism and the subsequent blood pressure response. Ten healthy males consumed an acute equimolar dose of NO (∼5.76 mmol) in the form of a concentrated beetroot juice drink (BR; 55 mL), a non-concentrated beetroot juice drink (BL; 456 mL) and a solid beetroot flapjack (BF; 60 g). A drink containing soluble beetroot crystals (BC; ∼1.40 mmol NO) and a control drink (CON; 70 mL deionised water) were also ingested. BP and plasma, salivary and urinary [NO] and [NO] were determined before and up to 24 h after ingestion. All NO-rich vehicles elevated plasma, salivary and urinary nitric oxide metabolites compared with baseline and CON (P<0.05). The peak increases in plasma [NO] were greater in BF (371 ± 136 nM) and BR (369 ± 167 nM) compared to BL (283 ± 93 nM; all P<0.05) and BC (232 ± 51 nM). BR, but not BF, BL and BC, reduced systolic (∼5 mmHg) and mean arterial pressure (∼3-4 mmHg; P<0.05), whereas BF reduced diastolic BP (∼4 mmHg; P < 0.05). Although plasma [NO] was elevated in all conditions, the consumption of a small, concentrated NO-rich fluid (BR) was the most effective means of reducing BP. These findings have implications for the use of dietary NOsupplements when the main objective is to maintain or improve indices of cardiovascular health.