Search

Background: Nitrate (NO 3 - )-rich beetroot (BR) juice supplementation has been shown to improve cardiovascular function via reduction to nitrite (NO 2 - ) and then to the bioactive molecule nitric oxide (NO). However, limited research exists for the role of inorganic NO 2 - that is contained naturally within BR., Objective: As BR juice can naturally contain both NO 3 - and NO 2 - the objective of this study was to evaluate the individual effects of NO 3 - and NO 2 - consumed from BR on plasma [NO 3 - ]/[NO 2 - ] and their subsequent effects on various cardiovascular measures., Design: In four separate treatments, 11 healthy adults consumed 250 mL of BR containing one of the following: (i) high NO 3 - , low NO 2 - (HL; 572 mg NO 3 - , 32 mg NO 2 - ); (ii) medium NO 3 - , medium NO 2 - (MM; 280 mg NO 3 - , 237 mg NO 2 - ); (iii) low NO 3 - , medium NO 2 - (LM; 43 mg NO 3 - , 262 mg NO 2 - ); (iv) placebo (PL; low NO 3 - , low NO 2 - : 8 mg NO 3 - , 5.8 mg NO 2 - ). Plasma [NO 3 - ]/[NO 2 - ], blood pressure, heart rate, mean arterial pressure (MAP), cardiac output and stroke volume were measured at baseline and every hour or second hour for 6 h post-BR consumption., Outcomes: Ingestion of the HL and MM BR increased plasma [NO 2 - ] and [NO 3 - ] after 2 h, with both remaining elevated after 6 h ( p < 0.05). LM increased plasma [NO 3 - ] ( p < 0.05) but did not increase plasma [NO 2 - ] compared to PL ( p = 0.177). MAP was lower following the consumption of HL at 4 h and LM at 6 h ( p < 0.05)., Conclusion: Inorganic NO 3 - consumption is the critical factor in elevating plasma [NO 3 - ] and [NO 2 - ]; however, both NO 2 - and NO 3 - show potential to reduce MAP. The known reduction of systolic blood pressure (SBP)/diastolic blood pressure (DBP) following NO 3 - supplementation was not observed, making it unclear if NO 2 - contributes to a reduction in SBP/DBP alongside NO 3 - .

Dietary nitrate (NO 3 - ) supplementation, which can enhance performance in exercise settings involving repeated high-intensity efforts, has been linked to improved skeletal muscle contractile function. Although muscular strength is an important component of explosive movements and sport-specific skills, few studies have quantified indices of muscular strength following NO 3 - supplementation, particularly isokinetic assessments at different angular velocities. We performed a systematic review and meta-analysis to determine whether dietary NO 3 - supplementation improves peak torque, as assessed by the gold standard method of isokinetic dynamometry, and if this effect was linked to the angular velocity imposed during the assessment. Dialnet, Directory of Open Access Journals, MEDLINE, PubMed, SciELO, Scopus, and SPORTDiscus were searched for articles using the following search strategy: (nitrate OR beet*) AND (supplement* OR nutr* OR diet*) AND (isokinetic OR strength OR "resistance exercise" OR "resistance training" OR "muscular power"). The meta-analysis of data from 5 studies with 60 participants revealed an overall effect size of -0.01 for the effect of nitrate supplementation on isokinetic peak torque, whereas trivial effect sizes ranging from -0.11 to 0.16 were observed for independent velocity-specific (90°/s, 180°/s, 270°/s, and 360°/s) isokinetic peak torque. Four of the five studies indicated that dietary NO 3 - supplementation is not likely to influence voluntary knee extensor isokinetic torque across a variety of angular velocities. These results suggest that NO 3 - supplementation does not influence isokinetic peak torque, but further work is required to elucidate the potential of NO 3 - supplementation to influence other indices of muscular strength, given the dearth of experimental evidence on this topic.

: Dietary nitrate (NO 3 - ) has been reported to improve endothelial function (EF) and blood pressure (BP). However, most studies only assess large-vessel EF with little research on the microvasculature. Thus, the aim of the present pilot study is to examine NO 3 - supplementation on microvascular and large-vessel EF and BP. Twenty older adults (63 ± 6 years) were randomized to a beetroot juice (BRJ) or placebo (PLA) group for 28 (±7) days and attended three laboratory visitations. Across visitations, blood pressure, microvascular function and large-vessel EF were assessed by laser Doppler imaging (LDI) with iontophoresis of vasoactive substances and flow-mediated dilatation (FMD), respectively. Plasma NO 3 - concentrations, BP and the presence of NO 3 - reducing bacteria were also assessed. Plasma NO 3 - increased following two weeks of BRJ supplementation ( p = 0.04) along with a concomitant decrease in systolic and diastolic BP of approximately -6 mmHg and -4 mmHg, respectively ( p = 0.04; p = 0.01, respectively). BP remained unchanged in the PLA group. There were no significant differences in endothelium-dependent or endothelium-independent microvascular responses between groups. FMD increased by 1.5% following two weeks of BRJ ( p = 0.04), with only a minimal (0.1%) change for the PLA group. In conclusion, this pilot study demonstrated that medium-term BRJ ingestion potentially improves SBP, DBP and large-vessel EF in healthy older adults. The improvements observed in the present study are likely to be greater in populations presenting with endothelial dysfunction. Thus, further prospective studies are warranted in individuals at greater risk for cardiovascular disease., Competing Interests: The authors declare no conflicts of interest.

Dietary nitrate, through the enterosalivary nitrate-nitrite-NO pathway, can improve blood pressure and arterial stiffness. How long systemic nitrate and nitrite remain elevated following cessation of high nitrate intake is unknown. In 19 healthy men and women, the time for salivary and plasma nitrate and nitrite to return to baseline after 7 days increased nitrate intake from green leafy vegetables was determined. Salivary and plasma nitrate and nitrite was measured at baseline [D0], end of high nitrate diet [D7], day 9 [+2D], day 14 [+7D] and day 21 [+14D]. Urinary nitrite and nitrate was assessed at D7 and +14D. Increased dietary nitrate for 7 days resulted in a more than fourfold increase in saliva and plasma nitrate and nitrite (p < 0.001) measured at [D7]. At [+2D] plasma nitrite and nitrate had returned to baseline while saliva nitrate and nitrite were more than 1.5 times higher than at baseline levels. By [+7D] all metabolites had returned to baseline levels. The pattern of response was similar between men and women. Urinary nitrate and nitrate was sevenfold higher at D7 compared to +14D. These results suggest that daily ingestion of nitrate may be required to maintain the physiological changes associated with high nitrate intake.