Beetroot juice and exercise: pharmacodynamic and dose-response relationships
01 Aug 2013-Journal of Applied Physiology (American Physiological Society Bethesda, MD)-Vol. 115, Iss: 3, pp 325-336
TL;DR: There is no additional improvement in exercise tolerance after ingesting BR containing 16.8 compared with 8.4 mmol NO3(-).
Abstract: Dietary supplementation with beetroot juice (BR), containing approximately 5-8 mmol inorganic nitrate (NO3(-)), increases plasma nitrite concentration ([NO2(-)]), reduces blood pressure, and may positively influence the physiological responses to exercise. However, the dose-response relationship between the volume of BR ingested and the physiological effects invoked has not been investigated. In a balanced crossover design, 10 healthy men ingested 70, 140, or 280 ml concentrated BR (containing 4.2, 8.4, and 16.8 mmol NO3(-), respectively) or no supplement to establish the effects of BR on resting plasma [NO3(-)] and [NO2(-)] over 24 h. Subsequently, on six separate occasions, 10 subjects completed moderate-intensity and severe-intensity cycle exercise tests, 2.5 h postingestion of 70, 140, and 280 ml BR or NO3(-)-depleted BR as placebo (PL). Following acute BR ingestion, plasma [NO2(-)] increased in a dose-dependent manner, with the peak changes occurring at approximately 2-3 h. Compared with PL, 70 ml BR did not alter the physiological responses to exercise. However, 140 and 280 ml BR reduced the steady-state oxygen (O2) uptake during moderate-intensity exercise by 1.7% (P = 0.06) and 3.0% (P < 0.05), whereas time-to-task failure was extended by 14% and 12% (both P < 0.05), respectively, compared with PL. The results indicate that whereas plasma [NO2(-)] and the O2 cost of moderate-intensity exercise are altered dose dependently with NO3(-)-rich BR, there is no additional improvement in exercise tolerance after ingesting BR containing 16.8 compared with 8.4 mmol NO3(-). These findings have important implications for the use of BR to enhance cardiovascular health and exercise performance in young adults.
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Andrews University1, Australian Institute of Sport2, University of Wyoming3, University of Western Australia4, Western Australian Institute of Sport5, McMaster University6, Messiah College7, Bangor University8, German Sport University Cologne9, Vrije Universiteit Brussel10, Maastricht University Medical Centre11, University of Guelph12, World Anti-Doping Agency13, English Institute of Sport14, International Olympic Committee15
TL;DR: The appropriate use of some supplements can benefit the athlete, but others may harm the athlete’s health, performance, and/or livelihood and reputation and expert professional opinion and assistance is strongly advised before an athlete embarks on supplement use.
Abstract: Nutrition usually makes a small but potentially valuable contribution to successful performance in elite athletes, and dietary supplements can make a minor contribution to this nutrition programme. Nonetheless, supplement use is widespread at all levels of sport. Products described as supplements target different issues, including (1) the management of micronutrient deficiencies, (2) supply of convenient forms of energy and macronutrients, and (3) provision of direct benefits to performance or (4) indirect benefits such as supporting intense training regimens. The appropriate use of some supplements can benefit the athlete, but others may harm the athlete's health, performance, and/or livelihood and reputation (if an antidoping rule violation results). A complete nutritional assessment should be undertaken before decisions regarding supplement use are made. Supplements claiming to directly or indirectly enhance performance are typically the largest group of products marketed to athletes, but only a few (including caffeine, creatine, specific buffering agents and nitrate) have good evidence of benefits. However, responses are affected by the scenario of use and may vary widely between individuals because of factors that include genetics, the microbiome and habitual diet. Supplements intended to enhance performance should be thoroughly trialled in training or simulated competition before being used in competition. Inadvertent ingestion of substances prohibited under the antidoping codes that govern elite sport is a known risk of taking some supplements. Protection of the athlete's health and awareness of the potential for harm must be paramount; expert professional opinion and assistance is strongly advised before an athlete embarks on supplement use.
457 citations
Cites background from "Beetroot juice and exercise: pharma..."
...There appears to be an upper limit to the benefits of consumption (i.e., no greater benefit from 16.8 mmol [1,041 mg] vs. 8.4 mmol [521 mg]; Wylie et al., 2013)....
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TL;DR: NO3− increased exercise capacity in heart failure with preserved ejection fraction by targeting peripheral abnormalities and reduced arterial wave reflections, which are linked to left ventricular diastolic dysfunction and remodeling.
Abstract: Background— Inorganic nitrate (NO 3 − ), abundant in certain vegetables, is converted to nitrite by bacteria in the oral cavity. Nitrite can be converted to nitric oxide in the setting of hypoxia. We tested the hypothesis that NO 3 − supplementation improves exercise capacity in heart failure with preserved ejection fraction via specific adaptations to exercise. Methods and Results— Seventeen subjects participated in this randomized, double-blind, crossover study comparing a single dose of NO 3 -rich beetroot juice (NO 3 − , 12.9 mmol) with an identical nitrate-depleted placebo. Subjects performed supine-cycle maximal-effort cardiopulmonary exercise tests, with measurements of cardiac output and skeletal muscle oxygenation. We also assessed skeletal muscle oxidative function. Study end points included exercise efficiency (total work/total oxygen consumed), peak o 2 , total work performed, vasodilatory reserve, forearm mitochondrial oxidative function, and augmentation index (a marker of arterial wave reflections, measured via radial arterial tonometry). Supplementation increased plasma nitric oxide metabolites (median, 326 versus 10 μmol/L; P =0.0003), peak o 2 (12.6±3.7 versus 11.6±3.1 mL O 2 ·min −1 ·kg −1 ; P =0.005), and total work performed (55.6±35.3 versus 49.2±28.9 kJ; P =0.04). However, efficiency was unchanged. NO 3 − led to greater reductions in systemic vascular resistance (−42.4±16.6% versus −31.8±20.3%; P =0.03) and increases in cardiac output (121.2±59.9% versus 88.7±53.3%; P =0.006) with exercise. NO 3 − reduced aortic augmentation index (132.2±16.7% versus 141.4±21.9%; P =0.03) and tended to improve mitochondrial oxidative function. Conclusions— NO 3 − increased exercise capacity in heart failure with preserved ejection fraction by targeting peripheral abnormalities. Efficiency did not change as a result of parallel increases in total work and o 2. NO 3 − increased exercise vasodilatory and cardiac output reserves. NO 3 − also reduced arterial wave reflections, which are linked to left ventricular diastolic dysfunction and remodeling. Clinical Trial Registration— URL: www.clinicaltrials.gov. Unique identifier: NCT01919177.
257 citations
TL;DR: Overall objective of this review is to provide a brief knowledge about the valuable phytochemicals and bioactive compounds present in beetroot and their association with health benefits, beetroot processing for food application and their effect on beetroot pigment.
249 citations
Cites background from "Beetroot juice and exercise: pharma..."
...Some nitrite is converted into nitric oxide when swallowed into the acidic medium of the stomach, whereas remain nitrite is absorbed to proliferate circulating plasma nitrite (Wylie et al., 2013)....
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...The dietary supplementation with beetroot juice, positively impact the biological responses to exercise and improves the cardiovascular health (Wylie et al., 2013)....
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TL;DR: In this paper, the amounts of various compounds (minerals, betalains, oxalic acid, phenolic acids, and sugars) in juice prepared from seven different beetroot varieties cultivated in Upper Austria were determined.
189 citations
Cites background from "Beetroot juice and exercise: pharma..."
...There is good agreement that nitrate supplementation by beetroot juice improves exercise tolerance through vascular control and elevated O2 delivery to skeletal muscles (Ferguson et al., 2013; Pinna et al., 2014; Wylie et al., 2013)....
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TL;DR: One week of daily dosing with BRJ (6.1 mmol inorganic nitrate) significantly improves submaximal aerobic endurance and blood pressure in elderly HFpEF patients.
Abstract: Objectives This study sought to determine whether a relatively low single dose or a week-long dosage of dietary inorganic nitrate could improve exercise tolerance in patients with heart failure with preserved ejection fraction (HFpEF). Background Exercise intolerance is the primary manifestation of HFpEF and is largely due to noncardiac factors that reduce oxygen delivery to active skeletal muscles. A recent study showed improved exercise capacity in patients with HFpEF after a single, acute dose of beetroot juice (BRJ) (12.9 mmol inorganic nitrate) while another recent study showed neutral and negative effects of an organic nitrate. Methods Twenty HFpEF patients (69 ± 7 years of age ) were enrolled in an initial cross-over design comparing a single, acute dose of BRJ (6.1 mmol nitrate) to a nitrate-depleted placebo BRJ. A second phase, 1 week of daily doses, used an all-treated design in which patients consumed BRJ for an average of 7 days. The primary outcome of the study was submaximal aerobic endurance, measured as cycling time to exhaustion at 75% of measured maximal power output. Results No adverse events were associated with the intervention. Submaximal aerobic endurance improved 24% after 1 week of daily BRJ dosing (p = 0.02) but was not affected by the single, acute dose of the BRJ compared to placebo. Consumption of BRJ significantly reduced resting systolic blood pressure and increased plasma nitrate and nitrite in both of the dosing schemes. Conclusions One week of daily dosing with BRJ (6.1 mmol inorganic nitrate) significantly improves submaximal aerobic endurance and blood pressure in elderly HFpEF patients.
151 citations
Cites background from "Beetroot juice and exercise: pharma..."
...A larger nitrate dose results in increased plasma nitrite (45) which is the essential factor in producing physiological changes....
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References
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TL;DR: Throughout middle and old age, usual blood pressure is strongly and directly related to vascular (and overall) mortality, without any evidence of a threshold down to at least 115/75 mm Hg.
9,101 citations
TL;DR: The DBP results suggest that for the large majority of individuals, whether conventionally "hypertensive" or "normotensive", a lower blood pressure should eventually confer a lower risk of vascular disease.
4,397 citations
TL;DR: It is suggested that nitrite represents a major bioavailable pool of NO, and a new physiological function for hemoglobin as a nitrite reductase is described, potentially contributing to hypoxic vasodilation.
Abstract: Nitrite anions comprise the largest vascular storage pool of nitric oxide (NO), provided that physiological mechanisms exist to reduce nitrite to NO. We evaluated the vasodilator properties and mechanisms for bioactivation of nitrite in the human forearm. Nitrite infusions of 36 and 0.36 μmol/min into the forearm brachial artery resulted in supra- and near-physiologic intravascular nitrite concentrations, respectively, and increased forearm blood flow before and during exercise, with or without NO synthase inhibition. Nitrite infusions were associated with rapid formation of erythrocyte iron-nitrosylated hemoglobin and, to a lesser extent, S-nitroso-hemoglobin. NO-modified hemoglobin formation was inversely proportional to oxyhemoglobin saturation. Vasodilation of rat aortic rings and formation of both NO gas and NO-modified hemoglobin resulted from the nitrite reductase activity of deoxyhemoglobin and deoxygenated erythrocytes. This finding links tissue hypoxia, hemoglobin allostery and nitrite bioactivation. These results suggest that nitrite represents a major bioavailable pool of NO, and describe a new physiological function for hemoglobin as a nitrite reductase, potentially contributing to hypoxic vasodilation.
1,714 citations
"Beetroot juice and exercise: pharma..." refers background in this paper
...(10) reported acutely increased blood flow to exercising forearm muscle following infusion of NO2 into the brachial artery....
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TL;DR: Combination low dose drug treatment increases efficacy and reduces adverse effects and three drugs at half standard dose are estimated to lower blood pressure and thereby reduce the risk of stroke by 63% and ischaemic heart disease events by 46% at age 60-69.
Abstract: Objective To determine the average reduction in blood pressure, prevalence of adverse effects, and reduction in risk of stroke and ischaemic heart disease events produced by the five main categories of blood pressure lowering drugs according to dose, singly and in combination.
Design Meta-analysis of 354 randomised double blind placebo controlled trials of thiazides, β blockers, angiotensin converting enzyme (ACE) inhibitors, angiotensin II receptor antagonists, and calcium channel blockers in fixed dose.
Subjects 40 000 treated patients and 16 000 patients given placebo.
Main outcome measures Placebo adjusted reductions in systolic and diastolic blood pressure and prevalence of adverse effects, according to dose expressed as a multiple of the standard (recommended) doses of the drugs.
Results All five categories of drug produced similar reductions in blood pressure. The average reduction was 9.1 mm Hg systolic and 5.5 mm Hg diastolic at standard dose and 7.1 mm Hg systolic and 4.4 mm Hg diastolic (20% lower) at half standard dose. The drugs reduced blood pressure from all pretreatment levels, more so from higher levels; for a 10 mm Hg higher blood pressure the reduction was 1.0 mm Hg systolic and 1.1 mm Hg diastolic greater. The blood pressure lowering effects of different categories of drugs were additive. Symptoms attributable to thiazides, β blockers, and calcium channel blockers were strongly dose related; symptoms caused by ACE inhibitors (mainly cough) were not dose related. Angiotensin II receptor antagonists caused no excess of symptoms. The prevalence of symptoms with two drugs in combination was less than additive. Adverse metabolic effects (such as changes in cholesterol or potassium) were negligible at half standard dose.
Conclusions Combination low dose drug treatment increases efficacy and reduces adverse effects. From the average blood pressure in people who have strokes (150/90 mm Hg) three drugs at half standard dose are estimated to lower blood pressure by 20 mm Hg systolic and 11 mm Hg diastolic and thereby reduce the risk of stroke by 63% and ischaemic heart disease events by 46% at age 60-69.
1,083 citations