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Inorganic nitrate (NO3-) supplementation has been shown to improve cardiovascular health indices in healthy adults. The purpose of this study was to investigate how the vehicle of NO3- administration can influence NO3- metabolism and the subsequent blood pressure response. Ten healthy males consumed an acute equimolar dose of NO3- (∼5.76 mmol) in the form of a concentrated beetroot juice drink (BR; 55 mL), a non-concentrated beetroot juice drink (BL; 456 mL) and a solid beetroot flapjack (BF; 60 g). A drink containing soluble beetroot crystals (BC; ∼1.40 mmol NO3-) and a control drink (CON; 70 mL deionised water) were also ingested. BP and plasma, salivary and urinary [NO3-] and [NO2-] were determined before and up to 24 h after ingestion. All NO3--rich vehicles elevated plasma, salivary and urinary nitric oxide metabolites compared with baseline and CON (P<0.05). The peak increases in plasma [NO2-] were greater in BF (371 ± 136 nM) and BR (369 ± 167 nM) compared to BL (283 ± 93 nM; all P<0.05) and BC (232 ± 51 nM). BR, but not BF, BL and BC, reduced systolic (∼5 mmHg) and mean arterial pressure (∼3-4 mmHg; P<0.05), whereas BF reduced diastolic BP (∼4 mmHg; P < 0.05). Although plasma [NO2-] was elevated in all conditions, the consumption of a small, concentrated NO3--rich fluid (BR) was the most effective means of reducing BP. These findings have implications for the use of dietary NO3-supplements when the main objective is to maintain or improve indices of cardiovascular health.
Primary study
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The advent of medical nutrition therapy and nutritional physiology affords the opportunity to link diet to specific cardiovascular mechanisms, suggesting novel treatments for cardiovascular disease. This study tests the hypothesis that beetroot juice increases the plasma nitric oxide (NO) concentration, which is associated with improvements in cardiorespiratory function at rest and during submaximal aerobic exercise. The subjects were 12 healthy, young adult, normotensive African-American females, with a body mass of 61 ± 2 kg, body fat of 28% ± 4%, and peak oxygen consumption of 26 ± 3 mL·kg(-1)·min(-1). The subjects were studied at rest and during cycle ergometer exercise at 40%, 60%, and 80% of peak oxygen consumption. Plasma NO concentration, respiratory quotient (RQ), minute ventilation, systolic and diastolic blood pressure (SBP and DBP), heart rate, and oxygen consumption were compared between isocaloric, isovolumetric placebo control orange juice and experimental beetroot juice treatments on separate days. The beetroot juice treatment increased plasma NO concentration and decreased oxygen consumption, SBP, and the heart rate-SBP product at rest and at 40%, 60%, and 80% of peak oxygen consumption in the absence of significant effects on RQ, minute ventilation, heart rate, and DBP. These findings suggest that, in healthy subjects, beetroot juice treatments increase plasma NO concentration and decrease cardiac afterload and myocardial oxygen demand at rest and during 3 submaximal levels of aerobic exercise. Future studies should determine the cellular and molecular mechanisms responsible for the improvement in cardiorespiratory function associated with dietary nitrate supplementation and whether they translate into better cardiovascular function and exercise tolerance in individuals with a compromised cardiovascular system.
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The burden of hypertension in Sub-Saharan African countries is rising. Low-cost and effective interventions are needed to mitigate these alarming trends. No evidence is available on the use of dietary nitrate for treating hypertension in African populations. The objectives of this study are to assess the feasibility and efficacy of using beetroot and folate as a combined dietary intervention to treat Tanzanian adults with pre- and mild to moderate hypertension. This was a three-arm double-blind, placebo-controlled, parallel randomised clinical trial conducted within the Hai Demographic Surveillance Site in the Kilimanjaro region in Tanzania. 48 participants were randomised to one of three groups for a 60-day intervention period. Group 1: Combined dietary intervention (beetroot juice and folate), Group 2: Single dietary intervention (beetroot juice and placebo capsule), and Group 3: Control group (placebo beetroot juice and placebo capsule). The primary outcome of the trial was to evaluate the feasibility of the study in a low-income setting. Trial assessments included resting clinic and ambulatory 24-hr blood pressure measurements, lifestyle and dietary questionnaires and collection of biological samples. Our cohort included 8 (16.7%) males and 40 (83.3%) females with mean age 60.7 years (SD 6.5). The mean (SD) BMI, clinic systolic blood pressure and ambulatory systolic blood pressure at baseline were 27.6 kg/m2 (5.4), 151.0 (19.4), and 140.4 (15.0) mmHg, respectively. Eight (16.7%) participants were classified as pre-hypertensive, 20 (41.7%) as stage-1 hypertensive, and 20 (41.7%) as stage-2 hypertensive. Overall, the results support the feasibility of a study of this nature within a hypertensive African population. Trial registration number: ISRCTN67978523. © 2019 The Author(s)
Primary study
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Abstract Background The diet's inorganic nitrate (NO3-) may provide a physiological substrate for reducing nitrate (NO2-) to NO independent of the endothelium. Studies suggest that inorganic NO3- has beneficial effects on cardiovascular health. Objective This study evaluated the acute effects of 500 mL nitrate-rich beetroot juice (BRJ; containing 11.5mmol NO3-) on blood pressure and endothelial function in treated hypertensive patients. Methods A randomized, placebo-controlled, crossover study was conducted in treated hypertensive patients (n=37; women=62%) who underwent clinical and nutritional evaluation and assessment of central hemodynamic parameters and microvascular reactivity. The significance level was p<0.05. Results The mean age was 59±7 years, and mean systolic and diastolic blood pressures were 142±10/83±9mmHg. There was a significant increase in the subendocardial viability ratio (SEVR; 149±25 vs. 165±30%, p<0.001) and reduction in ejection duration (ED; 37±4 vs. 34±4%, p<0.001) in the beetroot phase but no significant SEVR difference in the control phase. The % increase in perfusion (155 vs. 159 %, p=0.042) was significantly increased in the beetroot phase, which was not observed in the control phase. In the beetroot phase, the change in SEVR showed a significant correlation with the change in the area under the curve of post-occlusive reactive hyperemia (AUC-PORH) (r=0.45, p=0.012). The change in ED showed a significant correlation with the post-intervention perfusion peak (r=-0.37, p=0.031) and AUC-PORH (r=-0.36, p=0.046). Conclusions The acute ingestion of BRJ by hypertensive patients resulted in an improvement of endothelial function, which was associated with higher subendocardial viability and performance in myocardial contraction.
Systematic review
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Without references
Anderson, OK, Martinez-Ferran, M, Lorenzo-Calvo, J, Jiménez, SL, and Pareja-Galeano, H. Effects of nitrate supplementation on muscle strength and mass: a systematic review. J Strength Cond Res 36(12): 3562-3570, 2022-This systematic review examines the effect of dietary nitrate supplementation (SUP) on muscle strength and hypertrophy when combined with physical exercise. The databases PubMed, Web of Science, and MEDLINE were searched for full-text articles published between January 2000 and June 2020. For inclusion, studies had to report on the effects of SUP administered as acute or chronic doses together with a standardized exercise protocol on muscle strength and hypertrophy compared with placebo in healthy adults who were sedentary, physically active, or professional athletes. Twelve studies (1,571 subjects) were finally selected. In 5 studies, the SUP regime was acute, and in 7, it was chronic. SUP was nitrate-rich beetroot juice in 9 studies, a potassium nitrate capsule in 1, and increased dietary nitrate in 2. Ingested nitrate was 64-1,200 mg. Of the 12 studies, 6 observed an ergogenic effect of SUP compared with placebo. These findings indicate that muscle strength gains are possible provided the dose, format, frequency, period, and exercise test are appropriate. Best results were observed with a minimum acute dose of 400 mg of nitrate provided as beetroot juice/shot taken 2-2.5 hours before exercise involving low- and high-intensity muscle contractions. This SUP regime seems to improve muscle efficiency in terms of reduced phosphocreatine and energy costs (P-magnetic resonance spectroscopy) and improved time to exhaustion.
Primary study
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The purpose of this clinical study in women after menopause is to investigate whether the daily intake of nitrate from beetroot juice over 12 weeks enhances the positive effect of exercise training on vascular function, blood pressure and physical performance.
The risk of cardiovascular diseases (CVD) increases with advancing age and women are particularly affected. In women, the decline in the sex hormone oestrogen in the blood circulation with menopause contributes to impaired vascular function and an increased CVD risk; in part through increased inflammatory processes, oxidative stress, and a reduced body\'s own production of nitric oxide (NO). NO is a signaling molecule that is important for vascular function. Endurance-based exercise training is a key lifestyle strategy to prevent CVD. However, studies indicate that exercise is less effective in terms of its health-promoting adaptations in women after menopause as compared with men of similar age.
This study investigates the effect of exercise training in combination with the intake of nitrate-rich beetroot juice on functions of the cardiovascular system. Nitrate is a nitrogen compound that is found naturally in plant foods (e.g. beetroot juice) and is converted to NO in the human body. Results of previous studies indicate vasodilatory, blood pressure-lowering and performance-enhancing effects as well as positive influences on inflammatory processes and oxidative stress following nitrate intake. The hypothesis is that nitrate intake concomitant to training promotes training adaptations and further improves vascular function, blood pressure and physical performance compared to training without nitrate intake.
For the study, 54 untrained postmenopausal women (with the ages between 45 and 65 years) will be recruited and randomly allocated into two groups. Both groups will undergo 12 weeks of endurance-based exercise training. One group will receive nitrate-rich beetroot juice, and the other nitrate-depleted beetroot juice (as placebo). Vascular function, blood pressure, maximum oxygen uptake, and blood biomarkers for nitrate metabolism, inflammation status and oxidative stress will be examined.
The anticipated study results will provide new insights into whether nitrate as a \'training adjunct\' improves health-promoting training adaptations in women after menopause. The overall aim is to improve the cardiovascular health and performance of middle-aged women and reduce their increased CVD risk.
Primary study
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This article is not included in any systematic review
Alcohol use is increasingly prevalent in modern society and is known to cause cognitive impairment and dysregulation of inflammatory responses. In the present study, the investigators want to perform a randomised controlled trials to test whether nitrate could change the oral microbiota and benefit the cognitive impairment in alcohol dependence patients. The investigators survey the oral bacterial communities in saliva samples of 70 alcohol dependent patients following 14 days of dietary inorganic nitrate (nitrate-rich beetroot juice, \~750 mg NO3- /d) and placebo (nitrate-depleted beetroot juice, \~1 mg NO3- /d) supplementation.
Primary study
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This article is not included in any systematic review
Individuals with cold sensitivity have low peripheral skin blood flow and skin temperature possibly due to reduced nitric oxide (NO•) bioavailability. Beetroot has a high concentration of inorganic nitrate and may increase NO-mediated vasodilation. Using a placebo-controlled, double blind, randomised, crossover design, this study tested the hypotheses that acute beetroot supplementation would increase the rate of cutaneous rewarming following a local cold challenge and augment endothelium-dependent vasodilation in cold sensitive individuals. Thirteen cold sensitive participants completed foot and hand cooling (separately, in 15 °C water for 2 min) with spontaneous rewarming in 30 °C air whilst skin temperature and cutaneous vascular conductance (CVC) were measured (Baseline). On two further separate visits, participants consumed 140 ml of either concentrated beetroot juice (nitrate supplementation) or nitrate-depleted beetroot juice (Placebo) 90 min before resting seated blood pressure was measured. Endothelial function was assessed by measuring CVC at the forearm, finger and foot during iontophoresis of 1% w/v acetylcholine followed by foot and hand cooling as for Baseline. Plasma nitrite concentrations significantly increased in nitrate supplementation compared to Placebo and Baseline (502 ± 246 nmol L-1; 73 ± 45 nmol L-1; 74 ± 49 nmol L-1 respectively; n = 11; P < 0.001). Resting blood pressure and the response to foot and hand cooling did not differ between conditions (all P > 0.05). Nitrate supplementation did not alter endothelial function in the forearm, finger or foot (all P > 0.05) compared to Placebo. Despite a physiologically meaningful rise in plasma nitrite concentrations, acute nitrate supplementation does not alter extremity rewarming, endothelial function or blood pressure in individuals with cold sensitivity.
Primary study
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This article is not included in any systematic review
High blood pressure in pregnancy affects around 10% of pregnancies, and is associated with serious adverse outcomes for both mother and baby. Treatment options for the management of high blood pressure in pregnancy are currently limited. Studies in non-pregnant individuals have shown that supplementation with dietary nitrate, using beetroot juice, can significantly lower blood pressure and improve blood flow. This study aims to investigate whether supplementation with dietary nitrate (via beetroot juice) can improve blood pressure regulation in pregnant women with chronic high blood pressure, and will also determine whether this can improve blood flow across the placenta.
Primary study
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This article is not included in any systematic review
Dental erosion happens when teeth lose some of their parts because of acid from the things people eat and/or drink or even from their stomach. It can make their teeth hurt and become sensitive. The mouth has a protective shield called salivary pellicle that helps, and there are some special bacteria called Nitrate-reducing bacteria (NRB) that can be good for the mouth and heart. Eating some fruits and vegetables or drinking beetroot can make these bacteria thrive, which might help the heart and blood pressure. This study wants to see how drinking beetroot juice affects these good bacteria in your mouth for people with healthy teeth and those with erosion. This study aims to find out if drinking beetroot juice can change the saliva and bacteria in the mouth for the better, in people with both healthy teeth and those with dental erosion.
The proposed study is part of a PhD educational project and will be a double blind, randomised design, crossover trial for the effect of nitrate supplement on healthy control and people with dental erosion (PwDE). This study aims to explore the effect of nitrate supplement on oral microbiome in WMS and SP and its impact on blood pressure and arterial stiffness in healthy controls and PwDE.