Beetroot Juice Intake Research Articles

Beetroot juice intake positively influenced gut microbiota and inflammation but failed to improve functional outcomes in adults with Long COVID: A pilot randomized controlled trial

Beetroot juice intake positively influenced gut microbiota and inflammation but failed to improve functional outcomes in adults with Long COVID: A pilot randomized controlled trial

Nitrate and Nitrite Concentrations in Fingertip Serum Following Beetroot Juice Ingestion Correlate with Those in Venous Plasma.

Dietary nitrate (NO3-) supplementation can offer health benefit and improve exercise performance by increasing nitric oxide (NO) through NO3--nitrite (NO2-)-NO pathway. Individuals may benefit from dietary NO3- supplementation by monitoring blood [NO3-] and [NO2-], although a simple and practical method for assessing blood [NO3-] and [NO2-] has not been established. We examined whether fingertip serum samples could substitute for venous plasma samples in assessing [NO3-] and [NO2-]. Ten young adults consumed 140 mL of nitrate-rich beetroot juice. Fingertip serum and venous plasma samples were collected at baseline and every hour for up to 4 h after ingestion. [NO3-] and [NO2-] were similar between samples at baseline, whereas they were higher in fingertip serum throughout the post-ingestion periods. Significant correlations existed between fingertip serum vs. venous plasma for both [NO3-] and [NO2-] throughout post-drink periods, except [NO3-] assessed at 2 and 4 h after ingestion of beetroot juice. We show that although fingertip serum [NO3-] and [NO2-] overestimate those measured by venous plasma after dietary NO3- intake (125-141% and 156-183% of venous values), [NO3-] and [NO2-] in fingertip serum samples may be utilized for assessing blood [NO3-] and [NO2-] levels, although [NO3-] assessment may lack precision compared to [NO2-].

The Effects of Acute Beetroot Juice Intake on Glycemic and Blood Pressure Responses When Controlling for Medication in Individuals with Type 2 Diabetes: A Pilot Study.

Physical inactivity and poor dietary choices contribute to the rise in cardiometabolic diseases in the United States. It remains critical to identify strategies that may mitigate the negative impact of these behaviors. Several studies have shown that the consumption of dietary inorganic nitrate may improve vascular health and glucose regulation in animal models and some human studies. However, the improvements in glucose regulation have yet to be corroborated in humans with type 2 diabetes (T2D). Therefore, the purpose of this study was to assess the acute effects of beetroot juice (BRJ) on glycemic and hemodynamic responses in individuals with T2D while controlling for medication. Seven participants with a clinical diagnosis of T2D were recruited into this study and were temporarily removed from blood pressure- and glucose-lowering medications. Hemodynamic measurements (pulsewave velocity) and an oral glucose tolerance test (glycemic response) were measured following consumption of either BRJ or a denitrolized placebo. Saliva and blood samples were collected at baseline and two and four hours post supplementation to measure changes in nitrate and nitrite concentrations. We detected significant improvements in total plasma glucose exposure (p = 0.022) and the SVR change score (p = 0.009) in the BRJ condition. This study demonstrated that BRJ consumption can improve oral glucose tolerance in individuals with T2D while controlling for medication; however, future larger-cohort randomized controlled trials are needed to confirm if BRJ is a viable treatment for glucose control in individuals with T2D.

Acute inorganic nitrate ingestion does not impact oral microbial composition, cognitive function, or high-intensity exercise performance in female team-sport athletes.

The purpose of this study was to investigate the effects of acute nitrate (NO3-)-rich beetroot juice ingestion on explosive and high-intensity exercise performance, oral microbiota composition, and cognitive flexibility (i.e., function), before and after maximal intermittent running exercise. Fifteen women team-sport athletes were assigned in a randomized, double-blind, crossover design to consume concentrated NO3--depleted beetroot juice (PL; 0.1mmol NO3-) and NO3--rich beetroot juice (BR; 12.0mmol NO3-) 2.5h prior to performing a battery of exercise performance tasks and cognitive testing before and after the Yo-Yo intermittent recovery level 1 (YYIR1) running test. Resting plasma [NO3-] and plasma nitrite ([NO2-]) were elevated following BR (P < 0.001). BR did not impact global composition or relative abundance of taxa in the oral microbiome (P > 0.05) or cognitive flexibility before or after exercise (P > 0.05). There was no significant difference in performance during 20-m (PRE, PL: 4.38 ± 0.27 vs. BR: 4.38 ± 0.32s; POST, PL: 4.45 ± 0.29 vs. BR: 4.43 ± 0.35s) and 10-m sprints (PRE, PL 2.78 ± 0.15 vs. BR 2.79 ± 0.18s; POST, PL: 2.82 ± 0.16 vs. BR: 2.81 ± 0.19s), isokinetic handgrip dynamometry, medicine ball throw, horizontal countermovement jump, or YYIR1 (PL: 355 ± 163m vs. BR: 368 ± 184m) between BR and PL (P > 0.05). These findings indicate that acute dietary NO3- may not influence the oral microbiome, explosive and high-intensity exercise performance, or cognitive function in women team-sport athletes.

Effects of acute beetroot juice intake on performance, maximal oxygen uptake, and ventilatory efficiency in well-trained master rowers: a randomized, double-blinded crossover study.

Beetroot juice (BRJ) intake has been considered a practical nutritional strategy among well-trained athletes. This study aimed to assess the effects of BRJ intake on performance, cardiorespiratory and metabolic variables during a simulated 2000-meter rowing ergometer test in well-trained master rowers. Ten well-trained male master rowers (30-48 years) participated in a randomized, double-blind, crossover design for 3 weeks. In the first week, a researcher explained all the experimental procedures to the participants. In the next two weeks, the participants were tested in 2 rowing ergometer sessions, separated from each other by a 7-day washout period. In both strictly identical sessions, the participants randomly drank BRJ or placebo (PL) 3 hours before the start of the tests. Subsequently, the participants carried out the 2000-meter rowing ergometer tests. Oxygen saturation and blood lactate measurements were performed before starting (pretest) and at the end of the test (posttest). Performance parameters and cardiorespiratory variables were recorded during the rowing ergometer test. An improvement in time trial performance was observed, with a mean difference of 4 seconds (90% confidence limits ± 3.10; p ≤ 0.05) compared to PL. Relative and absolute increased (mean difference of 2.10 mL·kg-1·min-1, 90% confidence limits ± 1.80; mean difference of 0.16 L·min-1 90% confidence limits ± 0.11, respectively; p ≤ 0.05) compared to PL. No ergogenic effect was observed on ventilatory efficiency and blood lactate concentrations after BRJ intake. Acute BRJ intake may improve time trial performance as well as in well-trained master rowers. However, BRJ does not appear to improve ventilatory efficiency.

Effects of Acute Beetroot Juice and Sodium Nitrate on Selected Blood Metabolites and Response to Transient Ischemia: A Crossover Randomized Clinical Trial

BackgroundModification of the nitrate (NO3)–nitrite (NO2)–nitric oxide (NO) pathway can be induced by oral intake of inorganic NO3 (NIT) or NO3-rich products, such as beetroot juice (BRJ). ObjectivesThe primary aim of this study was to evaluate the plasma changes in betaine, choline, trimethylamine (TMA), trimethylamine N-oxide (TMAO), and NO3/NO2 (NOx) concentrations over 4 h after single oral ingestion of NIT or BRJ. The flow-mediated skin fluorescence (FMSF) method was applied to measure the changes in nicotinamide adenine dinucleotide reduced form (NADH) in response to transient ischemia and reperfusion. We hypothesized that various sources of NO3 may differently affect endothelial and mitochondrial functions in healthy human subjects. MethodsIn a randomized crossover trial, 8 healthy young adults ingested 800 mg NO3 from either NIT or BRJ on 2 separate days with ≥3 d apart. Venous blood samples were collected every hour, and FMSF determination was applied bihourly. ResultsPlasma betaine and choline concentrations peaked at 1 h after BRJ ingestion, and remained significantly higher than baseline values at all time points (P < 0.001 and P < 0.001, compared to preingestion values). Over time, BRJ was more effective in increasing NOx compared with NIT (fixed-trial effect P < 0.001). Baseline fluorescence decreased after both NIT and BRJ consumption (fixed-time effect P = 0.005). Transient ischemia and reperfusion response increased because of NO3 consumption (fixed-time effect P = 0.003), with no differences between trials (P = 0.451; P = 0.912; P = 0.819 at 0, 2, and 4 h, respectively). ConclusionsAcute ingestion of BRJ elevated plasma betaine and choline, but not TMA and TMAO. Moreover, plasma NOx levels were higher in the BRJ trial than in the NIT trial. Various sources of NO3 positively affected endothelial and mitochondrial functions.This trial was registered at clinicaltrials.gov as NCT05004935.

Low Carbohydrate, High Fat Diet Alters the Oral Microbiome without Negating the Nitrite Response to Beetroot Juice Supplementation.

A low carbohydrate, high fat (LCHF) diet in athletes increases fat oxidation but impairs sports performance, potentially due to impaired exercise economy. Dietary nitrate supplementation can improve exercise economy via an increase in nitric oxide production, which is initiated by the reduction of nitrate to nitrite within the oral cavity. This reaction is dependent on the presence of nitrate-reducing oral bacteria, which can potentially be altered by dietary changes, including a LCHF diet. This study explored the effect of a LCHF diet on the oral microbiome and subsequent changes to plasma nitrite concentration following nitrate supplementation. Following five days of LCHF or high carbohydrate (HCHO) control dietary intervention, highly trained male race walkers consumed 140 mL beetroot juice containing 8.4 mmol nitrate; they then provided (a) blood samples for plasma nitrate and nitrite analysis and (b) saliva samples for 16S rRNA sequencing of the oral microbiome. The LCHF diet (n = 13) reduced oral bacterial diversity and changed the relative abundance of the genera Neisseria (+10%), Fusobacteria (+3%), Prevotella (-9%), and Veillonella (-4%), with no significant changes observed following the HCHO diet (n = 11). Following beetroot juice ingestion, plasma nitrite concentrations were higher for the LCHF diet compared to the HCHO diet (p = 0.04). However, the absence of an interaction with the trial (pre-post) (p = 0.71) suggests that this difference was not due to the dietary intervention. In summary, we found an increase in plasma nitrate and nitrite concentrations in response to nitrate supplementation independent of diet. This suggests the oral microbiome is adaptive to dietary changes and can maintain a nitrate reduction capacity despite a decrease in bacterial diversity following the LCHF diet.

High or low volume beetroot juice supplementation might positively affect physical capacity and isokinetic muscle function in power athletes

BACKGROUND: Beetroot juice is an ergogenic aid containing high levels of nitrate and is known to have many physiological benefits. OBJECTIVE: This study aimed to examine the effects of beetroot juice supplementation on the physical capacity and isokinetic muscle function of power athletes. METHODS: Thirteen power athletes were orally administered three different volumes of beetroot juice: placebo (70 ml), low-volume beetroot juice (70 ml), and high-volume beetroot juice (140 ml). The Harvard step test, 20 m sprint, side-step, reaction time, Wingate test, blood lactate analysis, and isokinetic knee and trunk tests were performed to confirm their physical capacity and isokinetic muscle function. Significant differences between the drink groups were determined using repeated-measures ANOVA. RESULTS: There were no significant differences in the Harvard step, side step, whole-body reaction time, anaerobic power, blood lactate concentration, and isokinetic muscular strength in the knee and trunk for all groups. However, the 20 m sprint and isokinetic muscular endurance of the knee extensor were significantly higher with beetroot juice intake. CONCLUSIONS: Our findings suggest that &gt; 70 ml of beetroot juice supplement before performance may be useful as an ergogenic supplement to improve performance-related physical fitness, including speed and muscular endurance, in power athletes.

Effects of beetroot juice supplementation on vascular functional and structural changes in aged mice.

This study investigated whether beetroot juice (BRJ) ingestion ameliorates aging-induced functional and structural changes in vasculature. Aged mice (98-100 weeks old) were supplemented with BRJ (nitrate: 3.5 mmol/L) or drinking water for 4 weeks and compared with young mice (12-15 weeks old). The vasorelaxant response of isolated aortas to acetylcholine was markedly weaker in aged mice than in young mice, but the attenuated relaxation was significantly improved in BRJ-supplemented aged mice. The acetylcholine-induced relaxation was completely abolished by Nω -nitro-l-arginine methyl ester in all groups. Additionally, the response to sodium nitroprusside was comparable among the three groups. The aortic medial thickness was significantly greater in aged mice than in young mice, and BRJ supplementation did not suppress this thickening. Plasma nitrate levels were significantly higher in BRJ-supplemented aged mice than in non-supplemented aged mice. Conversely, non-supplemented aged mice had high plasma levels of thiobarbituric acid-reactive substances, but the levels were suppressed in BRJ-supplemented aged mice. These findings suggest that BRJ ingestion improves vascular endothelial dysfunction associated with aging, at least in part, by enhancing nitric oxide bioavailability and reducing oxidative stress. Therefore, beetroot ingestion may be a highly useful self-medication option to prevent vascular aging.

Short-term beetroot juice supplementation improves muscle speed and power but does not reduce blood pressure or oxidative stress in 65–79 y old men and women

We have previously demonstrated that acute ingestion of inorganic nitrate (NO3−)-rich beetroot juice (BRJ), a source of nitric oxide (NO) via the NO3− → nitrite (NO2−) → NO pathway, can improve muscle speed and power in older individuals. It is not known, however, whether this effect is maintained or perhaps even enhanced with repeated ingestion, or if tolerance develops as with organic nitrates, e.g., nitroglycerin. Using a double-blind, placebo-controlled, crossover design, we therefore studied 16 community-dwelling older (age 71 ± 5 y) individuals after both acute and short-term (i.e., daily for 2 wk) BRJ supplementation. Blood samples were drawn and blood pressure was measured periodically during each ∼3 h experiment, with muscle function determined using isokinetic dynamometry. Acute ingestion of BRJ containing 18.2 ± 6.2 mmol of NO3− increased plasma NO3− and NO2− concentrations 23 ± 11 and 2.7 ± 2.1-fold over placebo, respectively. This was accompanied by 5 ± 11% and 7 ± 13% increases in maximal knee extensor speed (Vmax) and power (Pmax), respectively. After daily supplementation for 2 wk, BRJ ingestion elevated NO3− and NO2− levels 24 ± 12 and 3.3 ± 4.0-fold, respectively, whereas Vmax and Pmax were 7 ± 9% and 9 ± 11% higher than baseline. No changes were observed in blood pressure or in plasma markers of oxidative stress with either acute or short-term NO3− supplementation. We conclude that both acute and short-term dietary NO3− supplementation result in similar improvements in muscle function in older individuals. The magnitudes of these improvements are sufficient to offset the decline resulting from a decade or more of aging and are therefore likely to be clinically significant.

Metabolic Biomarkers of Red Beetroot Juice Intake at Rest and after Physical Exercise.

Red beetroot is known to be a health-promoting food. However, little attention is placed on intestinal bioactive compound absorption. The aim of the study was to assess the urinary red beetroot juice (RBJ) intake biomarkers and possible differences in RBJ's micronutrient absorption at rest or after physical exercise. This is a three-armed, single-blind study, involving seven healthy volunteers which were randomly divided into three groups and alternatively assigned to three experimental sessions: RBJ intake at rest, RBJ intake with physical activity, and placebo intake with physical activity. For each session, urine samples were collected before and 120, 180, and 240 min after the intake of RBJ or placebo. The same sampling times were employed for the experimental session at rest. The RBJ metabolic composition was also characterized to identify the urinary biomarkers derived from the intake. 4-methylpyridine-2-carboxylic acid, dopamine-3-O-sulfate, glutamine, and 3-hydroxyisobutyrate were identified as RBJ intake biomarkers. Physical activity significantly increased only the dopamine-3-O-sulfate excretion 120 min after RBJ intake. Urinary dopamine-3-O-sulfate is related to RBJ dopamine content, while 4-methylpyridine-2-carboxylic acid is a betanin or betalamic acid catabolite. The different excretions of these metabolites following physical activity suggest a possible effect on the RBJ uptake depending on different transport processes through the mucosa, namely diffusion-mediated transport for dopamine and saturable transcellular transport for betalamic acid derivatives. These results open new perspectives in improving the absorption of natural bioactive molecules through physical activity.

Effects of beetroot juice intake on repeated performance of competitive swimmers.

Background: Beetroot juice is a sport supplement with a high level of evidence on the physical performance enhancement. However, in swimming, there is no clear data about the effects of beetroot juice on performance. Objective: To investigate whether an acute intake of beetroot juice (BJ) improves the performance of competitive swimmers in a repeated maximum swimming effort. Method: Thirteen national-level swimmers (six females and seven males), participated in this randomized, double-blind crossover study. In two different trials, swimmers ingested a 70-mL placebo shot (.04mmol NO3 -; PLA) or a 70-mL Beet-It shot (6.4mmol of NO3 -beet juice [BJ]) 3h before undergoing a 6 × 100-m front-crawl maximal effort test with 7min rest between each 100m. Results: Overall, 100-m times showed no difference between the BJ and PLA groups (p = .364), although a possibly shorter time was observed for BJ in the last repetition (p = .104; mean difference [MD] = -.99s, mean-based inference [MBI] = 49/51/0). Participants in the BJ condition showed a possibly lower rate of perceived exertion in the first (p = .242, MD = -.85, MBI = 70/28/2) and second repetitions (p = .165, MD = 1.15, MBI = 83/16/1), whereas Total Quality Recovery scale scores were likely higher in the first (p = .110, MD = 1.15, MBI = 83/16/1) and third (p = .082, MD = -.77, MBI = 70/29/1) repetitions compared with those in the PLA group. Blood lactate concentration [La+] levels showed no differences between groups in any of the repetitions (p > .05, unclear), and we observed an increase in 100-m times for both BJ and PLA (BJ: p = .014, MD = -1.51s; PLA: p = .029, MD = -1.57s) after the fifth repetition. Conclusion: No clear differences in performance were observed in a 6 × 100-m repeated sprint test by competitive swimmers when supplementing (or not) with BJ. However, there was a trend toward a better recovery between efforts and a better tolerance of fatigue when swimmers ingested BJ.

Ameliorative Effects of Beetroot Juice Supplementation on Monocrotaline-Induced Pulmonary Hypertension in Rats

Beetroot is a nitrate-rich vegetable with cardiovascular benefits. This study examined whether ingestion of beetroot juice (BRJ) protects against pulmonary hypertension (PH). Rats were injected subcutaneously with 60 mg/kg monocrotaline (MCT) and randomized to receive either drinking water, low-dose BRJ (BRJ-L, nitrate content: 1.4 mmol/L), or high-dose BRJ (BRJ-H, nitrate content: 3.5 mmol/L), which was started 1 week after MCT injection and continued until the end of the experiment. Four weeks after MCT injection, right ventricle (RV) hypertrophy, right ventricular systolic pressure (RVSP) elevation, and pulmonary vascular remodeling were observed. These PH symptoms were less severe in rats supplemented with BRJ-L (Fulton index, p = 0.07; RVSP, p = 0.09, pulmonary arterial medial thickening, p &lt; 0.05), and the beneficial effects were more pronounced than those of BRJ-H supplementation. Plasma and RV nitrite and nitrate levels did not change significantly, even when BRJ-L and BRJ-H were administered. There were no differences in plasma thiobarbituric acid reactive substances (TBARS), a biomarker of oxidative stress, among the groups. BRJ-L supplementation significantly decreased RV TBARS levels compared to MCT alone (p &lt; 0.05), whereas BRJ-H supplementation did not. These findings suggest that starting BRJ supplementation from an early stage of PH ameliorates disease severity, at least partly through the inhibition of local oxidative stress. Habitual ingestion of BRJ may be useful for the management of PH.

Influence of Beetroot Juice Ingestion on Neuromuscular Performance on Semi-Professional Female Rugby Players: A Randomized, Double-Blind, Placebo-Controlled Study.

Beetroot juice (BRJ) is considered an ergogenic aid with good to strong evidence for improving human performance in sport modalities with similar demands to rugby. However, most of the studies were realized in male athletes with limited evidence in female athletes. Thus, the aim of this study was to explore the acute ingestion of BRJ in female rugby players. Fourteen semi-professional female rugby players (25.0 ± 3.7 years) belonging to a team from the First Spanish Female Rugby Division participated in this study. Participants were randomly divided into two groups that realized a neuromuscular battery after BRJ (140mL, 12.8 mmol NO3-) or placebo (PLAC, 140 mL, 0.08 mmol NO3-) ingestion on two different days separated by one week between protocols. The neuromuscular test battery consisted of a countermovement jump (CMJ), isometric handgrip strength (i.e., dominant), 10-m and 30-m sprint, agility t-test and Bronco test. Afterwards, participants reported a rate of perception scale (6-20 points) and side effects questionnaire associated with BRJ or PLAC ingestion. Statistically significant improvements were observed in CMJ (7.7%; p = 0.029; ES = 0.62), while no differences were reported in dominant isometric handgrip strength (-1.7%; p = 0.274; ES = -0.20); 10-m and 30-m sprint (0.5-0.8%; p = 0.441-0.588; ES = 0.03-0.18); modified agility t-test (-0.6%; p = 0.503; ES = -0.12) and Bronco test (1.94%; p = 0.459; ES = 0.16). BRJ ingestion could improve neuromuscular performance in the CMJ test, while no differences in sprint (10-m and 30-m sprint test), agility, isometric handgrip strength and endurance performance (i.e., Bronco test) were reported.

Effects of Acute Beetroot Juice Ingestion on Reactive Agility Performance

Beetroot juice (BRJ) is high in inorganic nitrate (NO3) which has been shown to enhance vascular function, cognition, and physical performance. Acute BRJ supplementation has been reported to enhance explosive resistance exercise performance and simple reaction time in diseased populations. However, it remains unknown if acute BRJ supplementation can enhance agility and reactive drills in healthy individuals, which are relevant to many sports. The purpose of this study was to investigate the effects of acute BRJ supplementation on simple reaction time and reactive agility performance. In a counterbalanced double-blinded manner, physically active males completed two trials each with a differing single-dose treatment: (1) Placebo (PL), (2) BRJ. Each treatment was consumed 2-hrs before experimental testing. Plasma Nitrate (NO3) and Nitrite (NO2) were measured via capillary blood sampling and colorimetric assay. Reaction time was assessed using a simple reaction time light test. Reactive agility was measured via a semi-circle drill and a get-up-and-go drill. All tests used FITLIGHT LED sensors to record response time. Each visit was separated by a 72-h washout period. Acute BRJ ingestion resulted in significantly greater plasma NO3 (p &lt; 0.001) and NO2 (p = 0.008) compared to PL. BRJ significantly improved response time during the semi-circle drill (p = 0.011) and get-up and go drill (p = 0.027) compared to PL. No differences between treatments were observed for simple reaction time (p = 0.279). Collectively, these findings suggest that acute BRJ ingestion may improve reactive agility performance likely mediated by systemic increases in NO3/NO2. Future research is needed to investigate how these findings translate to game-play and sports competition.

Dietary Nitrate Does Not Improve Neuromuscular Performance And Match-play Demands In Elite Female Hockey Players.

PURPOSE: Beetroot juice is a commonly used ergogenic aid that contains high levels of inorganic nitrate (NO3-) and that its intake has proven effectivity at increasing blood nitric oxide (NO) concentrations. The ingestion of beetroot juice has shown good evidence of benefits in endurance sports while team sports has been barely studied. In our knowledge, only a few studies have been developed in team sports athletes. The present study was designed to compare the acute effects of beetroot juice supplementation on physical performance and match-play demands in elite female field hockey players METHODS: Eleven well-trained female hockey players (22.78 ± 5.12 years) participated during the preparatory period of their hockey season in this study. Participants were randomly divided into two groups undergoing a neuromuscular test battery with ingestion of 70 mL beetroot juice (6.4 mmol NO3-) or 70 mL placebo (0.04 mmol NO3-) in two separated days with one week between protocols. A neuromuscular test battery consisted in different test such as; countermovement jump (CMJ), isometric handgrip strength (IHS), and repeated sprint ability test (RSA) were realized. Afterwards a simulated hockey match play (2 x 20 minutes) was realized and the data was recorded by Global Positioning System (GPS). RESULTS: No significant improvements were observed in any physical parameters analysed comparing beetroot juice versus placebo ingestion, CMJ (p = 0.776), IHS (p = 0.829), RSA (p = 0.466). Therefore, no differences were reported in any physical match demands measured by GPS (i.e., total distance covered, number of accelerations/decelerations, etc) (p = 0.063-0.941) CONCLUSIONS: Beetroot juice acute supplementation did not produce any statistically significant improvement in physical performance or match-play demands in elite female field hockey players

Plasma Nitrate and Nitrite Kinetics after Single Intake of Beetroot Juice in Adult Patients on Chronic Hemodialysis and in Healthy Volunteers: A Randomized, Single-Blind, Placebo-Controlled, Crossover Study

Nitric oxide (NO) contributes to maintaining normal cardiovascular and renal function. This bioactive signalling molecule is generally formed enzymatically by NO synthase in the vascular endothelium. NO bioactivity can also be attributed to dietary intake of inorganic nitrate, which is abundant in our diet, especially in green leafy vegetables and beets. Ingested nitrate is reduced to nitrite by oral commensal bacteria and further to NO systemically. Previous studies have shown that dialysis, by means of removing nitrate and nitrite from the body, can reduce NO bioactivity. Hence, dietary intervention approaches aimed to boost the nitrate–nitrite–NO pathway may be of benefit in dialysis patients. The purpose of this study was to examine the kinetics of plasma nitrate and nitrite after a single intake of nitrate-rich concentrated beetroot juice (BJ) in adult hemodialysis (HD) patients and in age-matched healthy volunteers (HV). Eight HD patients and seven HV participated in this single center, randomized, single-blind, placebo-controlled, crossover study. Each participant received a sequential single administration of active BJ (70 mL, 400 mg nitrate) and placebo BJ (70 mL, 0 mg nitrate) in a random order separated by a washout period of seven days. For the kinetic analysis, blood samples were collected at different time-points before and up to 44 h after BJ intake. Compared with placebo, active BJ significantly increased plasma nitrate and nitrite levels both in HD patients and HV. The area under the curve and the maximal concentration of plasma nitrate, but not of nitrite, were significantly higher in HD patients as compared with HV. In both groups, active BJ ingestion did not affect blood pressure or plasma potassium levels. Both BJs were well tolerated in all participants with no adverse events reported. Our data provide useful information in planning dietary nitrate supplementation efficacy studies in patients with reduced NO bioactivity.

Circulating nitrate-nitrite reduces oxygen uptake for improving resistance exercise performance after rest time in well-trained CrossFit athletes

This study aimed to determine the effects of circulating nitrate plus nitrite (NOx) concentrations on resistance exercise performance, VO2 and biomarkers of muscle damage. Eleven well-trained male CrossFit athletes (29.2 ± 3.7 years, 78.9 ± 5.4 kg, 175.1 ± 6.3 cm) carried out a resistance exercise test after drinking 140 mL of beetroot juice (BJ) or placebo. The test consisted of repeating the same resistance exercise routine twice: wall ball shots plus full back squat with 3-min rest (1st routine) or without rest (2nd routine) between the two exercises. Higher NOx plasma levels were verified after BJ than placebo in the pretest and post-test (p < 0.001). A higher number of repetitions was observed after BJ intake compared to placebo in the full back squat exercise during the first routine (p = 0.004). A significantly reduced VO2 was detected after BJ intake compared to placebo during rest and full back squat execution in the first routine (p < 0.05). Plasma myoglobin concentrations were significantly increased with BJ compared to placebo (p = 0.036). These results showed that plasma NOx levels reduced VO2 after BJ intake during rest time. These reduced VO2 was a key factor for improving full back squat performance during the first routine.

Prior beetroot juice ingestion offsets endothelial dysfunction following prolonged sitting.

Nutritional strategies to prevent endothelial dysfunction following prolonged sitting remain largely unknown. Given that beetroot juice (BRJ) ingestion enhances nitric oxide (NO) bioavailability, we aimed to evaluate whether prior BRJ ingestion would prevent sitting-induced endothelial dysfunction in the leg. Eleven healthy young males (n = 7) and females (n = 4) underwent two experimental trials of prolonged sitting with prior: 1) placebo (PL) ingestion (PL trial) and 2) BRJ ingestion (BRJ trial). All subjects ingested 140 mL of PL or BRJ (∼0.0055 or ∼12.8 mmol of nitrate, respectively) immediately before 3 h of sitting. Pre- and post-sitting measurements of popliteal artery flow-mediated dilation (FMD) and blood pressure, and blood collection were undertaken. During the sitting period, an hourly assessment of popliteal artery diameter and blood velocity, blood pressure, and blood collection were performed. Popliteal artery blood flow and shear rate were significantly and similarly reduced during the sitting period in both trials (P < 0.001). Plasma nitrate and NOx (total nitrite and nitrate) concentrations were significantly increased relative to baseline in the only BRJ trial, and the overall concentrations were significantly higher in the BRJ trial (P < 0.001). Popliteal artery FMD was significantly reduced after the sitting period in the PL trial (P < 0.05), whereas no reduction was observed in the BRJ trial. Therefore, prior BRJ ingestion would prevent sitting-induced leg endothelial dysfunction via enhancing NO bioavailability.NEW & NOTEWORTHY The present study elucidates that beetroot juice ingestion before prolonged sitting offsets sitting-induced leg endothelial dysfunction. Data from the present study provides novel physiological information that enhancing NO bioavailability by dietary nitrate supplementation is an effective tool for prevention of the detrimental vascular effects of prolonged sitting.

Dietary Nitrate Supplementation Does Not Alter Exercise Efficiency at High Altitude - Further Results From the Xtreme Alps Study.

IntroductionNitrate supplementation in the form of beetroot juice (BRJ) ingestion has been shown to improve exercise tolerance during acute hypoxia, but its effect on exercise physiology remains unstudied during sustained terrestrial high altitude exposure. We hypothesized that performing exercise at high altitude would lower circulating nitrate and nitrite levels and that BRJ ingestion would reverse this phenomenon while concomitantly improving key determinants of aerobic exercise performance.MethodsTwenty seven healthy volunteers (21 male) underwent a series of exercise tests at sea level (SL, London, 75 m) and again after 5–8 days at high altitude (HA, Capanna Regina Margherita or “Margherita Hut,” 4,559 m). Using a double-blind protocol, participants were randomized to consume a beetroot/fruit juice beverage (three doses per day) with high levels of nitrate (∼0.18 mmol/kg/day) or a nitrate-depleted placebo (∼11.5 μmoles/kg/day) control drink, from 3 days prior to the exercise trials until completion. Submaximal constant work rate cycle tests were performed to determine exercise efficiency and a maximal incremental ramp exercise test was undertaken to measure aerobic capacity, using breath-by-breath pulmonary gas exchange measurements throughout. Concentrations of nitrate, nitrite and nitrosation products were quantified in plasma samples collected at 5 timepoints during the constant work rate tests. Linear mixed modeling was used to analyze data.ResultsAt both SL and HA, plasma nitrate concentrations were elevated in the nitrate supplementation group compared to placebo (P < 0.001) but did not change throughout increasing exercise work rate. Delta exercise efficiency was not altered by altitude exposure (P = 0.072) or nitrate supplementation (P = 0.836). V̇O2peak decreased by 24% at high altitude (P < 0.001) and was lower in the nitrate-supplemented group at both sea level and high altitude compared to placebo (P = 0.041). Dietary nitrate supplementation did not alter other peak exercise variables or oxygen consumption at anaerobic threshold. Circulating nitrite and S-nitrosothiol levels unexpectedly rose in a few individuals right after cessation of exercise at high altitude.ConclusionWhilst regularly consumed during an 8 days expedition to terrestrial high altitude, nitrate supplementation did not alter exercise efficiency and other exercise physiological variables, except decreasing V̇O2peak. These results and those of others question the practical utility of BRJ consumption during prolonged altitude exposure.