Nitrate-rich beetroot juice vs. nitrate-rich chard gel : a phamacokinetic and pharmacodynamic comparison

It has been suggested that the pharmacokinetics of nitrate (NO3-) may differ depending on the delivery vehicle, although this has not yet been explored in the same group of study participants. PURPOSE: To compare the changes in blood pressure (BP), plasma [NO3-], nitrite [NO2-], and total nitroso species [RXNO] following ingestion of commercially available beetroot juice (BR) and NO3- rich chard gels (NG), matched for NO3- content. METHODS: ~500 mg nitrate was administered acutely to nine healthy male adults using two different formulations in a randomised order. In one arm they ingested two 60 g NG gels and in the other 117 ml of concentrated BR instead. Samples of venous blood were collected and BP was measured prior to ingestion of the supplements and at frequent intervals for 6 h after ingestion. Blood samples were centrifuged and, following separation of the plasma, [RXNO] was measured using gas-phase chemiluminescence and [NO3-] and [NO2-] were measured using HPLC.RESULTS: Plasma [NO3-] increased to a similar extent and peaked 60 min after ingestion, in both conditions (BR ? 376 ± 29 ?M; NG ? 332 ± 34 ?M, both P0.05). CONCLUSIONS: While there were no differences in peak [NO2-], [NO3-], or the extent to which SBP was reduced between NG and BR conditions, plasma [NO2-] peaked sooner following ingestion of NG (90 min) compared to BR (210 min), and RXNO increased to a greater extent following BR. The underlying mechanism(s) for these pharmacokinetic differences are unclear, but must relate to the composition of the supplements likely affecting the reduction of NO3- to NO2- in the oral cavity and/or the gastrointestinal trac