Background: Dietary inorganic nitrate is reduced to (nitric oxide) NO in the body. Beetroot is a rich source of dietary inorganic nitrate and has been shown to lower brachial blood pressure (BP) by this mechanism. The effect on aortic (central) BP, which may be a better predictor of cardiovascular disease, has not been studied. Objectives: To measure the effect of dietary nitrate in beetroot juice on central BP at both 30 minutes and over a 6 hour period post-beetroot juice consumption. Method: A double-blind, randomised, placebo-controlled crossover trial was performed in nine healthy, normotensive men and women aged between 22 and 45 years. Participants were randomised to receive beetroot juice (6.5-7.3 mmol nitrate) or placebo juice (0.04-0.06 mmol nitrate). Brachial and central BP were measured at baseline, 30 and 60 minutes post-ingestion, and at least hourly for the following 24 hours. Following a washout period, the procedure was repeated within seven days with crossover to the opposite arm of the trial. There were no dietary restrictions during the study. Results: Compared with placebo, beetroot juice lowered central systolic BP at 30 minutes (change in beetroot juice: -2.6±3.4 mmHg vs. change in placebo: 1.8±5.9 mmHg, P=0.045). Beetroot juice also lowered central systolic BP averaged over 6 hours post-ingestion (beetroot: 106±8 mmHg vs. placebo: 111±11 mmHg, P=0.029). Conclusion: Consumption of beetroot juice lowered central BP. Beetroot juice could have a role in CV risk management in the general population, but further research is required to establish its long-term benefits, safety and tolerability.

This study aims to investigate the effects of different dietary nitrate supplements, versus placebo, on microbiological and immunological markers associated with oral health in people aged 18-65 years.

The main research questions are:

* How do different dietary nitrate supplements (beetroot crystals vs. beetroot juice) affect oral health markers, including salivary pH and oral microbiome composition?
* What is the acceptability and ease of integrating one of dietary nitrate supplements, made from beetroot but processed as freeze dried crystals or juice, into the daily diet?

To answer these questions, the study will compare results from three groups of participants, who will be randomly assigned to one of the following study arms:

Group 1: The control group will consume a placebo beetroot supplement completely free of nitrate in juice form.

Group 2: The beetroot juice group will consume a beetroot supplement standardised to contain \~ 400 mg of nitrate in juice form.

Group 3: The beetroot crystals group will consume a beetroot supplement standardised to contain \~400 mg of nitrate in freeze dried crystal form.

The study will follow a randomised, single-blind, placebo-controlled, parallel design, and the intervention will last for four weeks. Data will be collected by providing pre- and post-intervention saliva samples tongue swabs, and various questionnaires will be completed at baseline and at the end of the study. In addition, at the end of the second week of the intervention period, participants will be asked to collect a saliva sample over three consecutive days at home.

BACKGROUND:

Chronic obstructive pulmonary disease (COPD) results in exercise intolerance. Dietary nitrate supplementation has been shown to lower blood pressure (BP), reduce the oxygen cost of exercise, and enhance exercise tolerance in healthy volunteers. This study assessed the effects of dietary nitrate on the oxygen cost of cycling, walking performance and BP in individuals with mild-moderate COPD.

METHODS:

Thirteen patients with mild-moderate COPD were recruited. Participants consumed 70 ml of either nitrate-rich (6.77 mmol nitrate; beetroot juice) or nitrate-depleted beetroot juice (0.002 mmol nitrate; placebo) twice a day for 2.5 days, with the final supplement ~3 hours before testing. BP was measured before completing two bouts of moderate-intensity cycling, where pulmonary gas exchange was measured throughout. The six-minute walk test (6 MWT) was completed 30 minutes subsequent to the second cycling bout.

RESULTS:

Plasma nitrate concentration was significantly elevated following beetroot juice vs. placebo (placebo; 48 ± 86 vs. beetroot juice; 215 ± 84 µM, P = 0.002). No significant differences were observed between placebo vs. beetroot juice for oxygen cost of exercise (933 ± 323 vs. 939 ± 302 ml: min(-1); P = 0.88), distance covered in the 6 MWT (456 ± 86 vs. 449 ± 79 m; P = 0.37), systolic BP (123 ± 14 vs. 123 ± 14 mmHg; P = 0.91), or diastolic BP (77 ± 9 vs. 79 ± 9 mmHg; P = 0.27).

CONCLUSION:

Despite a large rise in plasma nitrate concentration, two days of nitrate supplementation did not reduce the oxygen cost of moderate intensity cycling, increase distance covered in the 6 MWT, or lower BP.

This study aims to determine whether dietary inorganic nitrate (in beetroot juice) is able to reduce overall thickening of the heart (left ventricular hypertrophy or LVH) and stiffness of the arteries when given to patients with persistently raised blood pressure (hypertension). Half the patients will receive the beetroot juice containing inorganic nitrate and half will receive beetroot juice from which the inorganic nitrate has been removed. The volunteers will take the juice every day for 4 months.

Nitrate supplementation in the form of beetroot juice has been shown to increase nitric oxide (NO) where nitrate can be reduced to nitrite and, subsequently, to NO through both nitric oxide synthase (NOS)-dependent and -independent pathways. We tested the hypothesis that nitrate supplementation would augment the NO component of the cutaneous vasodilatation to local skin heating in young, healthy humans. Participants reported to the lab for pre- and post-supplement local heating protocols. Nitrate supplementation consisted of one shot (70ml) of beetroot juice (0.45g nitrate; 5mM) for three days. Six participants were equipped with two microdialysis fibers on the ventral forearm and randomly assigned to lactated Ringer's (control) or continuous infusion of 20mM l-NAME (NOS inhibitor). The control site was subsequently perfused with l-NAME once a plateau in skin blood flow was achieved to quantify NOS-dependent cutaneous vasodilatation. Skin blood flow via laser-Doppler flowmetry (LDF) and mean arterial pressure (MAP) were measured; cutaneous vascular conductance (CVC) was calculated as LDF/MAP and normalized to %CVC<inf>max</inf>. Beetroot juice reduced MAP (Pre: 90±1mmHg vs. Post: 83±1mmHg) and DBP (Pre: 74±2mmHg vs. Post: 62±3mmHg) (P<0.05). The plateau phase of the local heating response at control sites was augmented post-beetroot juice (91±5%CVC<inf>max</inf>) compared to pre-beetroot juice (79±2%CVC<inf>max</inf>) (P<0.05). There was no difference in the %NOS-dependent vasodilatation from pre- to post-beetroot juice. These data suggest that nitrate supplementation via beetroot juice can reduce MAP and DBP as well as augment NOS-independent vasodilatation to local heating in the cutaneous vasculature of healthy humans.

Both recovery time of post-exercise muscle oxygenation and muscle strength decline with aging. Although beetroot consumption has been shown to improve muscle oxygenation and exercise performance in adults, these effects in the elderly has not been addressed. The aim of the present study was to evaluate the effect of a beetroot-based gel (BG) on muscle O2 saturation, blood volume (tHb) and handgrip strength in the elderly in response to handgrip exercise. In a randomized crossover double-blind design, twelve older subjects consumed BG (100 g of beetroot-based gel containing ~ 12 mmol nitrate) or PLA (100 g of nitrate-depleted gel nitrate-depleted). The subjects performed a rhythmic handgrip exercise which consisted of a one 1-min set at 30% of the maximal voluntary contraction (MVC) of each subject, followed by a 1 min recovery. The muscle oxygenation parameters and tHb were continuously monitored by using near-infrared spectroscopy. MVC was evaluated at baseline, immediately after exercise, and 30 min afterwards. The muscle O2 resaturation rate during exercise recovery was greater in the BG when compared to PLA condition (1.43 ± 0.77 vs 1.02 ± 0.48%.s-1; P < 0.05). Significant increase was observed in tHb during exercise recovery (10.25 ± 5.47 vs 6.72 ± 4.55 μM; P < 0.05) and significant reduction of handgrip strength decline was observed 30 min after exercise in BG (- 0.24 ± 0.18 vs-0.39 ± 0.20 N; P < 0.05). In summary, a single dose of a beetroot-based gel speeds up muscle O2 resaturation, increases blood volume and improves recovery of handgrip strength after handgrip exercise in older adults.

INTERVENTION:

Dietary nitrate will be ingested as beetroot juice. The intervention comprises a 6‐day supplementation period with either beetroot juice (140 mL daily) or nitrate‐depleted beetroot juice (placebo; 140 mL daily). After ingestion of the last bolus of beetroot or placebo juice, counter movement jump performance, maximal strength and muscular endurance will be assessed. Both experimental periods will be separated by a wash‐out period of at least 1 week.

CONDITION:

Dietary nitrate, Exercise performance ; ;

PRIMARY OUTCOME:

‐Counter movement jump performance ; ; ‐Maximal isometric voluntary contraction; ; ‐Maximal isokinetic voluntary contraction; ; ‐Isokinetic muscle endurance performance;

SECONDARY OUTCOME:

‐Plasma nitrate and nitrite

INCLUSION CRITERIA:

‐Healthy male ‐Recreationally active (0.5 – 8 h of sport activities per week on a non‐competitive base) ‐18‐40 years

Aims. To evaluate the possible additive effects of beetroot juice plus caffeine on exercise performance. Methods. In a randomized, double-blinded study design, fourteen healthy well-trained men aged 22 ± 3 years performed four trials on different occasions following preexercise ingestion of placebo (PLA), PLA plus 5 mg/kg caffeine (PLA+C), beetroot juice providing 8 mmol of nitrate (BR), and beetroot juice plus caffeine (BR+C). Participants cycled at 60% maximal oxygen uptake ([Formula: see text]max) for 30 min followed by a time to exhaustion (TTE) trial at 80% [Formula: see text]max. Saliva was collected before supplement ingestion, before exercise, and after the TTE trial for salivary nitrate, nitrite, and cortisol analysis. Results. In beetroot trials, saliva nitrate and nitrite increased >10-fold before exercise compared with preingestion (P ≤ 0.002). TTE in BR+C was 46% higher than in PLA (P = 0.096) and 18% and 27% nonsignificant TTE improvements were observed on BR+C compared with BR and PLA+C alone, respectively. Lower ratings of perceived exertion during TTE were found during 80% [Formula: see text]max on BR+C compared with PLA and PLA+C (P < 0.05 for both). Conclusions. Acute preexercise beetroot juice coingestion with caffeine likely has additive effects on exercise performance compared with either beetroot or caffeine alone.

Dietary nitrate supplementation has been shown to reduce the oxygen (O2) cost of exercise and enhance exercise tolerance in healthy individuals. This study assessed whether similar effects could be observed in individuals with type 2 diabetes (T2DM). In a randomized, double-blind, placebo-controlled crossover study, 48 participants with T2DM supplemented their diet for 4 days with either nitrate-rich beetroot juice (70ml/day, 6.43mmol nitrate/day) or nitrate-depleted beetroot juice as placebo (70ml/day, 0.07mmol nitrate/day). After each intervention period, resting plasma nitrate and nitrite concentrations were measured subsequent to participants completing moderate-paced walking. Pulmonary gas exchange was measured to assess the O2 cost of walking. After a rest period, participants performed the 6-min walk test (6MWT). Relative to placebo, beetroot juice resulted in a significant increase in plasma nitrate (placebo, 57±66 vs beetroot, 319±110µM; P < 0.001) and plasma nitrite concentration (placebo, 680±256 vs beetroot, 1065±607nM; P < 0.001). There were no differences between placebo juice and beetroot juice for the O2 cost of walking (946±221 vs 939±223ml/min, respectively; P = 0.59) and distance covered in the 6MWT (550±83 vs 554±90m, respectively; P = 0.17). Nitrate supplementation did not affect the O2 cost of moderate-paced walking or improve performance in the 6MWT. These findings indicate that dietary nitrate supplementation does not modulate the response to exercise in individuals with T2DM.

Research with young healthy individuals has shown that beetroot juice beverages that contain large amounts of nitrate can improve exercise performance. Currently, it is not know whether the consumption of beetroot juice beverages high in nitrate can improve exercise performance in higher functioning middle- to older-aged adults. Therefore, the purpose of this study is to compare the effect of two different beetroot juice beverages (one high in nitrate and one low in nitrate) on exercise performance in middle- to older-aged adults.