Dean Pomerleau Posted September 4, 2019 Report Share Posted September 4, 2019 This new study  along with the popular press article about it seem crazy at first, but it actually makes sense. In a double blind, placebo-controlled, crossover trial, the researchers found that blood pressure was decreased and tissue oxygenation was increased for several hours after exercise on a treadmill. This is not surprising. But when subjects gargled with an antibacterial mouthwash 30min after exercise, these beneficial post-exercise changes to blood pressure and tissue oxygenation were eliminated. It is well known that bacterial in the mouth convert nitrate to nitrite which in turn gets converted into the vasodilator nitrous-oxide. This process seems to happen acutely after exercise with beneficial results. The authors conclude: These findings show that nitrite synthesis by oral commensal bacteria is a key mechanism to induce the vascular response to exercise over the first period of recovery thereby promoting lower blood pressure and greater muscle oxygenation. This confirms Dr. Greger's advice from this video to avoid antibacterial mouthwash and toothpaste because they can interfere with the elaborate way the body converts dietary nitrates (e.g. from beets) into cardioprotective nitrous oxide. --Dean ----------  Free Radic Biol Med. 2019 Jul 29;143:252-259. doi: 10.1016/j.freeradbiomed.2019.07.035. [Epub ahead of print] Post-exercise hypotension and skeletal muscle oxygenation is regulated by nitrate-reducing activity of oral bacteria. Cutler C(1), Kiernan M(2), Willis JR(3), Gallardo-Alfaro L(4), Casas-Agustench P(1), White D(1), Hickson M(1), Gabaldon T(5), Bescos R(6). Post-exercise hypotension (PEH) is a common physiological phenomenon leading to lower blood pressure after acute exercise, but it is not fully understood how this intriguing response occurs. This study investigated whether the nitrate-reducing activity of oral bacteria is a key mechanism to trigger PEH. Following a randomized, double blind and crossover design, twenty-three healthy individuals (15 males/8 females) completed two treadmill trials at moderate intensity. After exercise, participants rinsed their mouth with antibacterial mouthwash to inhibit the activity of oral bacteria or a placebo mouthwash. Blood pressure was measured before, 1h and 2 h after exercise. The microvascular response to a reactive hyperaemia test, as well as blood and salivary samples were taken before and 2 h after exercise to analyse nitrate and nitrite concentrations and the oral microbiome. As expected, systolic blood pressure (SBP) was lower (1 h: -5.2 ± 1.0 mmHg; P < 0.001); 2 h: -3.8 ± 1.1 mmHg, P = 0.005) after exercise compared to baseline in the placebo condition. This was accompanied by an increase of circulatory nitrite 2 h after exercise (2h: 100 ± 13 nM) compared to baseline (59 ± 9 nM; P = 0.013). Additionally, an increase in the peak of the tissue oxygenation index (TOI) during the reactive hyperaemia response was observed after exercise (86.1 ± 0.6%) compared to baseline levels (84.8 ± 0.5%; P = 0.010) in the placebo condition. On the other hand, the SBP-lowering effect of exercise was attenuated by 61% at 1 h in the recovery period, and it was fully attenuated 2 h after exercise with antibacterial mouthwash. This was associated with a lack of changes in circulatory nitrite (P > 0.05), and impaired microvascular response (peak TOI baseline: 85.1 ± 3.1%; peak TOI post-exercise: 84.6 ± 3.2%; P > 0.05). Diversity of oral bacteria did not change after exercise in any treatment. These findings show that nitrite synthesis by oral commensal bacteria is a key mechanism to induce the vascular response to exercise over the first period of recovery thereby promoting lower blood pressure and greater muscle oxygenation. Copyright © 2019 Elsevier Inc. All rights reserved. DOI: 10.1016/j.freeradbiomed.2019.07.035 PMID: 31369841 Quote Link to comment Share on other sites More sharing options...
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