Dietary supplementation with beetroot juice (BRJ), a naturally rich source of nitrate, is an area of considerable interest to elite athletes as well as recreational exercisers. Nitrate and nitrite have previously been thought of as mainly final elimination products of nitric oxide (NO), but this view has been challenged and evidence indicates that these compounds can be converted to NO in vivo. We conducted a narrative review summarizing the literature regarding evidence of beetroot used as dietary supplement and its effects on training physiology and athletic performance in healthy and diseased populations. The databases PubMed and Web of Science were used to obtain articles. It was evident that BRJ supplementation had an effect on oxygen cost and consumption during exercise by more efficient adenosine triphosphate (ATP) production in combination with lower ATP consumption. However, the effect seems to be dependent on dose and duration. Effect on exercise performance is conflicting, time to exhaustion seems to increase but its effect on time-trial performance needs further elucidation. Ergogenic benefits might depend on individual aerobic fitness level, where individuals with lower fitness level may gain higher benefits regarding athletic performance. Dietary nitrate supplementation appears to have some effect on training performance in patients with peripheral artery disease, heart failure, and chronic pulmonary obstructive disease. However, larger randomized controlled trials are necessary to determine the overall utility of beetroot as a dietary supplement.

The purpose of this study is to investigate the effects of acute inorganic nitrate supplementation (with beetroot) on the regulation of sleep and neurovascular physiology.

The lung is the organ most affected by COVID-19. There are patients who successfully overcome the acute COVID-19 infection and their lungs return to a normal state. However, a significant number present dyspnea and fatigue as sequelae without having a pulmonary origin, but with a significant impact on functionality. In our published studies in relation to fatigue in patients with symptoms attributed to persistent COVID, the investigators have shown that there is muscle involvement, observing a decrease in mechanical efficiency. This muscle involvement causes stimulation of ventilation through the ergoreceptors, causing ineffective ventilation. This affectation can be explained by the findings obtained in the muscle biopsies that the investigators have performed, where the investigators observed a splitting of the basement membrane of the capillaries causing an alteration in the diffusion of metabolic substrates and oxygen.

The main objective of our project is to be able to observe the response in ventilatory efficiency in patients with symptoms of post-covid fatigue after ingesting beet juice.

Currently, there is a lack of evidence-based prevention strategies for respiratory infection and management of these conditions can be costly to the public. Airway nitric oxide provides a first line of defense against pathogens, and beetroot juice, a source of dietary nitrate, has been shown to elevate nitric oxide. The main objective of this project is to demonstrate that one week of supplementation with beetroot juice elevates airway nitric oxide during stressful periods in young adults and thereby can protect against respiratory viral infections.

Several previous studies observed a positive effect of beetroot supplementation on sports performance in athletes, mainly in endurance performance. However, less attention has been paid to its effects on short-duration performance, especially in youth athletes. Moreover, only a few previous investigations performed biochemical analyses, including pro-oxidant balance assessments. It is especially important because chronic nitrate intake might directly cause the production of reactive nitrogen species and reactive oxygen species in other subcellular compartments, leading to more oxidative stress. Additionally, no previous study verified the impact of beetroot intake on sleep.

According to current therapeutic approaches, a nitrate-dietary supplementation with beetroot juice (BRJ) is postulated as a nutritional strategy that might help to control arterial blood pressure in healthy subjects, pre-hypertensive population, and even patients diagnosed and treated with drugs. In this sense, a systematic review of random clinical trials (RCTs) published from 2008 to 2018 from PubMed/MEDLINE, ScienceDirect, and manual searches was conducted to identify studies examining the relationship between BRJ and blood pressure. The specific inclusion criteria were: (1) RCTs; (2) trials that assessed only the BRJ intake with control group; and (3) trials that reported the effects of this intervention on blood pressure. The search identified 11 studies that met the inclusion criteria. This review was able to demonstrate that BRJ supplementation is a cost-effective strategy that might reduce blood pressure in different populations, probably through the nitrate/nitrite/nitric oxide (NO₃-/NO₂-/NO) pathway and secondary metabolites found in Beta vulgaris. This easily found and cheap dietary intervention could significantly decrease the risk of suffering cardiovascular events and, in doing so, would help to diminish the mortality rate associated to this pathology. Hence, BRJ supplementation should be promoted as a key component of a healthy lifestyle to control blood pressure in healthy and hypertensive individuals. However, several factors related to BRJ intake (e.g., gender, secondary metabolites present in B. vulgaris, etc.) should be studied more deeply.

A number of vegetables have a high nitrate content which after ingestion can be reduced to nitrite by oral bacteria, and further to vasoprotective NO endogenously. In the present study, two separate randomly controlled, single-blind, cross-over, postprandial studies were performed in normotensive volunteers. Ambulatory blood pressure (BP) was measured over a 24 h period following consumption of either four doses of beetroot juice (BJ), 0, 100, 250 and 500 g (n 18), or three bread products, control bread (0 g beetroot), red beetroot- and white beetroot-enriched breads (n 14). Total urinary nitrate/nitrite (NO(x)) was measured at baseline, and at 2, 4 and 24 h post-ingestion. BJ consumption significantly, and in a near dose-dependent manner, lowered systolic BP (SBP, P < 0·01) and diastolic BP (DBP, P < 0·001) over a period of 24 h, compared with water control. Furthermore, bread products enriched with 100 g red or white beetroot lowered SBP and DBP over a period of 24 h (red beetroot-enriched bread, P <0·05), with no statistical differences between the varieties. Total urinary NO(x) significantly increased following the consumption of 100 g (P < 0·01), 250 g (P <0·001) and 500 g BJ (P <0·001) and after red beetroot-enriched bread ingestion (P <0·05), but did not reach significance for white beetroot-enriched bread compared with the no-beetroot condition. These studies demonstrated significant hypotensive effects of a low dose (100 g) of beetroot which was unaffected by processing or the presence of betacyanins. These data strengthen the evidence for cardioprotective BP-lowering effects of dietary nitrate-rich vegetables.

INTERVENTION:

Participants are randomised using a Latin‐Square method. Participants are allocated in a random order to receive the four interventions. The four interventions include: 1. 100g whole pre‐cooked beetroot 2. 200g whole pre‐cooked beetroot 3. 300g whole pre‐cooked beetroot 4. 200ml potassium nitrate solution. Participants are asked to consume the supplement within 15 minutes after baseline testing, and measurements will be taken for 5 hours post‐supplementation. The duration of each intervention will be five hours. The washout period between each phase will be one week.

CONDITION:

Age‐related degenerative diseases ; Nutritional, Metabolic, Endocrine ; Age‐related degenerative diseases

PRIMARY OUTCOME:

Differences in bioavailability of nitrate between incremental doses of beetroot and compared to a standard dose of potassium nitrate at five hours.

SECONDARY OUTCOME:

1. Differences in changes in blood pressure following each dose of nitrate supplementation and compared to a standard dose of potassium nitrate at five hours; 2. Differences in changes in endothelial function following each dose of nitrate supplementation and compared to a standard dose of potassium nitrate at five hours; 3. Differences in changes in exhaled nitric oxide following each dose of nitrate supplementation and compared to a standard dose of potassium nitrate at five hours; 4. Differences in bioavailability of betalains and phenolic compounds between incremental doses of beetroot and compared to a standard dose of potassium nitrate at five hours;

INCLUSION CRITERIA:

1. Non‐obese 2. Non‐smoker 3. Males aged between 18 and 35 or 60 and 75 4. Free of chronic illness

Ingested beetroot contains inorganic nitrate which is later converted to nitric oxide (NO) in the bloodstream. NO is an important signaling molecule with several physiological functions in the body including acting as a vasodilator, expanding arteries and improving blood flow. Beetroot juice contain inorganic nitrate and consumption of beetroot has been shown to improve skeletal muscle contractility and metabolism enhancing high-intensity exercise performance. Isotonic sports drinks contain carbohydrates and sodium, which also improve exercise performance by providing exogenous glucose for energy to the working muscle and central nervous system and enabling faster absorption of fluid into the bloodstream. The ingestion of exogenous nitrate and isotonic-carbohydrate drink are recognized strategies for promoting exercise performance but whether they can be effectively combined has not been shown. This study will compare the salivary nitrite response, muscle oxygenation and time-trial performance after ingestion of two isotonic drinks with high in nitrate or with no nitrate.

INTERVENTION:

Beetroot juice

CONDITION:

Endothelial function ; ;

PRIMARY OUTCOME:

Degree of correlation between FMD and

LTH SECONDARY OUTCOME:

• Involvement of NO in LTH response ; ; • Changes in FMD and LTH in response to beetroot juice consumption. ;

INCLUSION CRITERIA:

Non‐smokers: ‐ Healthy Men ‐ Age between 25‐65 years ‐ Non‐smoking for > 5 years ‐ Body mass index between 18 and 30 kg/m2 ‐ Capable and willing to give informed consent ‐ General good health, based on medical history and physical examination ‐ Systolic BP measured on day of the experiment should be < 160 mmHg Smokers: ‐ As for the non‐smokers ‐ In addition smoking at least on average 14 cigarettes per day for at least 5 years