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

Easton, Chris and McIlvenna, Luke and Monaghan, Chris and Fernandez, Bernadette O and Feelisch, Martin and Muggeridge, David J. (2016) Nitrate-rich beetroot juice vs. nitrate-rich chard gel : a phamacokinetic and pharmacodynamic comparison. In: American College of Sports Medicine Annual Meeting, 2016-05-31 - 2016-06-04.

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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 P<0.001). Plasma [NO2-] increased and peaked 210 min after ingestion of BR (? 234 ± 90 nM, P=0.04) and 90 min after NG administration (? 308 ± 159 nM, P=0.02), with no difference in peak values between conditions (P=0.69). RXNO peaked earlier following BR (120 min, ? 418 ± 145 nM, P<0.01) compared to NG (180 min, ? 171 ± 31 nM, P=0.03). The diffence in ? RXNO between BR and NG approached statistical significance (P=0.06). Systolic BP was reduced to a similar extent in both conditions from 90 min onwards, with the largest reduction measured after 210 min (BR ? 11 ± 1 nmmHg, P<0.01; NG ? 11 ± 1 mmHg, P<0.01). Diastolic BP was reduced 120 min (P=0.04) and 150 min (? 5 ± 2 nmmHg, P=0.02) after ingestion of NG, but did not change with BR (P>0.05).  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 tract