Objective: Dietary nitrate from vegetable sources such as beets appears to be a
safe, effective way to increase nitric oxide in the body, which improves
glucose uptake, skeletal muscle fatigue, neurotransmission, mitochondrial
respiration and vasodilation1,2. The purpose of this review was to determine the effects of beetroot
juice supplementation on performance in physically active males and females
between 16 and 45 years of age.
Methods: A literature review was conducted utilizing Pubmed, EBSCO, Google
Scholar, and Academic Search Complete. Search terms used included beetroot
exercise, beetroot performance, and nitric oxide supplementation.
Results: Fifteen articles published in the past 5 years examining beetroot juice
were selected for review. The Evidence Analysis Process was used to analyze
each study. Beetroot
supplementation is shown to increase plasma nitrite concentration, and time to
exhaustion during exercise3-5.
It also appears to decrease blood pressure, oxygen consumption, and time
trial duration1,6.
Conclusions: Beetroot supplementation may
have acute and long-term benefits on exercise performance. There is a need for larger sample sizes
and further research before it should be recommended to all athletes and active
individuals.
Recommendations: Further research needs to be conducted to determine the physiological
mechanisms, outcomes in a competitive setting, optimum dosing and timing, and
long-term safety.
References
1) Murphy M, Eliot K, Heuertz RM, Weiss E.
Whole beetroot consumption acutely improves running performance. J Acad Nutr
Diet. 2012;112:548-552. 2) Bailey
SJ, Vanhatalo A, Winyard PG, Jones AM. The nitrate-nitrite-nitric oxide
pathway: Its role in human exercise physiology. Eur J Sport Sci. 2011;12:309-320. 3) Cermak NM, Res P, Stinkens R,
Lundberg JO, Gibala MJ, van Loon L JC. No improvement in endurance performance
following a single dose of beetroot juice. Int J Sport Nutr Exerc Metab. 2012. 4) Bailey SJ, Fulford J, Vanhatalo A, et
al. Dietary nitrate supplementation enhances muscle contractile efficiency
during knee-extensor exercise in humans. J Appl Physiol. 2010;109:
135-148. 5) Larsen FJ, Weitzberg
E, Lundberg JO, Ekblom B. Dietary nitrate reduces maximal oxygen consumption while
maintaining work performance in maximal exercise. Free Radic Biol Med.
2010;48:342-347. 6) Vanhatalo A,
Bailey SJ, Blackwell JR, et al. Acute and chronic effects of dietary nitrate
supplementation on blood pressure and the physiological responses to moderate-intensity
and incremental exercise. Am J Physiol Regul Integ Comp Physiol.
2010;299:R1121-R1131.
Beetroot Juice Supplementation on Exercise & Athletic Performance
Introduction: Nitrate and Nitric Oxide
- Nitric Oxide (NO) is a signaling molecule that regulates various physiological responses 3
- Dietary rich sources of nitrates (NO3) include: green leafy vegetables & beetroot (BR)
- May contribute to cardiovascular (CV) health benefits seen with high vegetable consumption 6
- Sodium nitrate & nitrite linked to cancer in some animal studies
- BR juice is easily digested and may increase plasma nitrite (NO2) and NO stores 1
- BR juice side effect: 1Red urine (beeturia), Red stools, & Well tolerated
• Sodium nitrate shown to reduce oxygen cost of exercise8
Research Question: Does beetroot juice improve performance in physically active individuals?
Inclusion Criteria
• Age: 16-45 years
Exclusion Criteria
• Internet articles
Other Research Criteria
• Databases:
• Keywords:
• “Beetroot performance”
• “Nitric oxide supplementation”
• Search Dates:
Nitrate-Nitrite-NO Pathway
- NO3 (nitrate) reduced to NO2 (bioactive nitrite) by anaerobic bacteria in saliva16
- Swallow and absorb nitrites, reduced to nitric oxide by deoxyhemoglobin or xanthine oxidoreductase16
- Nitrate Ingestion
- Vegetables make up 60-80% NO3- intake16
- Lettuce, spinach and beetroot
- Peak NO3- plasma concentration seen in 60 minutes16
- 60% systemic NO3- excreted in urine
- 25% reduced to NO2- by bacteria in mouth
- Reduction does not occur after use of antibacterial mouthwash
- NO2- absorbed and reduced to NO in acidic stomach or the body (increased in hypoxic and acidic environments)
- Skeletal muscle hypoxic & acidic during exercise
Nitric Oxide
- Physiological processes16
- Skeletal muscle glucose uptake
- Neurotransmission
- Sarcoplasmic reticulum calcium handling
- Mitochondrial respiration
- Skeletal muscle fatigue
- Low exercise tolerance seen in individuals with impaired NO synthesis16
- Reduction of nitrite bypasses this process
Safety
- Nitrates & nitrites commonly used for preservation8,12
- Processed meats such as sausage and bacon
- Also found in drinking water and other foods
- Linked to cancer and methemoglobinemia12
- US EPA set contamination level in water at 44 mg/L
- WHO guidelines set at < or = 50 mg/L in water and 3.7 mg/kg body weight as the ADI
- Nitrates found in fruits & vegetables which are known to decrease cardiovascular and cancer risks8,12
- Antioxidants, fiber and or phytochemicals may be why no harmful effects are seen
- Obtaining nitrates from fruits & vegetables seems like the safest option and should be recommended over alternatives until further research is done12
Beetroot Juice Effects on Performance
BR & Nitrite Concentrations
- Increased by 105% after consuming 0.5 L/d for 6 days8
- Increased [NO2] 137% compared to the placebo (PL)1
- Concentrations significantly increased from 238 nM preingestion (0 min) to 532 nM postingestion (120 min)5
- Concentration significantly increased by ~30% from 389 nM to 472 nM post BR ingestion 15
- Concentrations increased significantly by ~40% 11
- Increased (BR 30.1 +/- 1.5 vs PL 1.5 +/- 0.2 umol/L) 4
BR & Systolic Blood Pressure (SBP)
- 0.5 L/day for 6 days decreased by 4%8
- No change 60 minutes after consuming 200 g BR12
- Significantly lowered SBP after 6 days of ~0.5 L BR juice per day 11
- 0.5 L BR juice had no significant effect on SBP 2 hours after ingestion 15
- Significantly lower SBP on day 6 of BR (-5 mmHg)1
BR & Blood Pressure
- 6 days of BR juice supplementation had no significant effect on diastolic blood pressure (DBP) 11
- Resting mean arterial pressure (MAP) was 2% lower in BR than PL (p=0.04)6
- Reduced MAP by -2mmHg after day 4 of BR1
- 0.5 L BR juice had no significant effect on DBP or MAP 2 hours after ingestion 15
BR & Oxygen Consumption (VO2)
- Nitrate supplementation decreased VO2 max from 3.72 + 0.33 to 3.62 + 0.31 L/min (P<0.05)9
- End exercise VO2 lower at 5 & 15 days13
- In hypoxia (11% O2, ~5,000 m altitude) VO2 decreased at rest by 8% and during exercise at 45% VO2 peak by 4% following 6 days of BR juice supplementation 11
- No change in competitive cyclists7
- Decreased VO2 from 2.98 + 0.57 to 2.82 + 0.58 L/min after supplementation (P<0.02) during the 4 lowest submaximal workloads10
- Mean VO2 was lower (1.8%) with 500 mL BR supplementation, but not significant (p=0.06) 15
BR & Time to Exhaustion
- Increased time to exhaustion from 524 + 31 to 563 + 30 s (p<0.13)9
- Aerobic time to failure improved by 15%; all subjects exercised longer following BR supplementation; longer time to task failure with knee-extension exercise8
- Significantly increased maximal apneic duration by 11% (p= 0.04)6
- Increased time to failure by 25% (p<0.01) 1
- In hypoxia, cyclists experienced a 5% increase in time to exhaustion after 6 days of BR supplementation 11
- Increased time to exhaustion in high-intensity exercise 2
- Increased tolerance to high intensity exercise 14
BR & Time Trials
- 41 sec faster 5-km time trial 60 min after eating 200 g beets12
- Improved time trial performance by 2.8% in 4-km trial & by 2.7% in 16.1-km trial7
- 10-km time trial improved, decreased time to completion 4
- Following 0.5 L BR juice, group mean reduction in cycling 50-mile time trial completion time (0.8% or 1.2 min)
- Not a significant difference for research, but may be during competition 15
- No significant difference in ~1 hour cycling time trial compared to placebo 5
Ergogenic Effect for Rowing
- Rowing performance was improved by 0.4% across all repetitions, and in the later stages of exercise by 1.7% 3
BR & Power Output
- Increased after 15 days of supplementation13
- Power output increased by 5% in 4-km trial & by 6% in 16.1-km trial7
- Power output was slightly, but not significantly, higher after 0.5 L BR supplementation during 50-mile cycling time trial 15
- No significant difference in power output over time between BR and placebo in ~1 hour cycling time trials
BR & Rating of Perceived Effort (RPE)
- No significant difference in RPE during maximal exercise under normal conditions, in hypoxia, or in hypoxia after BR supplementation (18.6 +/-0.3, 18.3+/-0.3, 18.5+/-0.3) 11
- No significant difference in mean RPE following 50-mile cycling time trial (BR 13.2+/-0.9 vs. PL 13.2+/-1.8) 15
BR & Cerebral & Muscle Oxygenation
Cerebral Oxygenation
- No difference in cerebral oxygenation status during submax and max exercise in hypoxia after 6 days of BR 11
Muscle Oxygenation
- Significantly improved muscle oxygenation status 11
- Tissue oxidation index (TOIs) were higher with BR supplementation compared to control during rest, submax, and max exercise in hypoxia after 6 days of BR supplementation
BR & Plasma Metabolites
- Plasma free fatty acids (FFA) concentration
- No difference in free fatty acid concentration at rest, postprandially, and/or following ~1 hour cycling time trial 5
- Lactate
- No difference in blood lactate concentration during a 50 mile cycling time trial 15
- No difference in blood lactate concentration at rest, postprandially, and/or following ~1 hour cycling time trial 5
- Plasma Glucose
- No difference in plasma glucose concentration at rest, postprandially, and/or following ~1 hour cycling time trial 5
- Insulin
- No difference in insulin concentration at rest, postprandially, and/or following ~1 hour cycling time trial 5
BR & Heart Rate (HR)
- No difference in group mean HR with BR supplementation with ~1 hour time trial 15
- No significant difference in HR with BR juice during 50 mile time trial 5
Future Research
- Physiological mechanism behind BR juice and performance is unclear 3
- No risk for positive drug test result with BR juice supplementation 3
- BR juice may improve performance but these results not found yet in competitive settings 3
- Optimum timing and dosing need to be established
- Possible risks with long-term supplementation should be researched
- Decreased Blood Pressure
- Decreased VO2 & O2 cost
- Decreased time trial duration
- Increased plasma [nitrite]
- Increased time to exhaustion
- Increased power output
Evidence Analysis Conclusion Statement
- Beetroot juice improves exercise performance in physically active individuals compared to individuals not receiving the treatment.
- Evidence Grade
- Grade II, Fair
- Majority of studies are of strong design, and fairly consistent results, however some variability in results still exists
- Several studies are by the same investigators, with relatively small sample size
- Additional confirmation of statistical significance would strengthen the magnitude of effect
Conclusion
- Beetroot appears to be a safe, natural form of nitrate
- Beetroot and beetroot juice consumption are effective at lowering blood pressure, decreasing the O2 cost of exercise, and increasing time to exhaustion with acute and long-term use
- Additional research needed to verify BR effects with larger sample sizes and determine most effective dosages and supplementation frequency
References
1. Bailey
SJ, Fulford J, Vanhatalo A, et al. Dietary nitrate supplementation enhances
muscle contractile efficiency during knee-extensor exercise in humans. J Appl
Physiol. 2010;109: 135-148.
2. Bailey SJ, Winyard P, Vanhatalo A, et al. Dietary nitrate
supplementation reduces the O2 cost of low-intensity exercise and enhances
tolerance to high-intensity exercise in humans. J Appl Physiol. 2009;
107:1144-1155.
3. Bond
H, Morton L, Braakhuis AJ. Dietary nitrate supplementation improves rowing
performance in well-trained rowers. Int J Sport Nutr Exerc Metab. 2012;22:251-256.
4. Cermak NM, Gibala M, van Loon LJ. Nitrate supplementation’s
improvement of 10-km time-trial performance in trained cyclists. Int J Sport Nutr Exerc Metab. 2012;22:64-71.
5. Cermak
NM, Res P, Stinkens R, Lundberg JO, Gibala MJ, van Loon L JC. No improvement in
endurance performance following a single dose of beetroot juice. Int J Sport
Nutr Exerc Metab. 2012.
References
6. Engan HK, Jones AM, Ehrenberg F, Schagatay E. Acute
dietary nitrate supplementation improves dry static apnea performance. Respir
Physiol Neurobiol. 2012;182:53-59. doi:10.1016/j.resp.2012.05.007
7. Lansley KE, Winyard PG, Bailey SJ, et al. Acute dietary
nitrate supplementation improves cycling time trial performance. Med Sci Sports
Exerc. 2011;43(6):1125-1131.
8. Lansley KE,
Winyard PG, Fulford J, et al. Dietary nitrate supplementation reduces the O2
cost of walking and running: A placebo-controlled study. J Appl Physiol. 2010;110:591-600.
9. Larsen FJ, Weitzberg E, Lundberg JO, Ekblom B. Dietary
nitrate reduces maximal oxygen consumption while maintaining work performance
in maximal exercise. Free Radic Biol Med. 2010;48:342-347.
10. Larsen FJ,
Weitzberg E, Lundberg JO, Ekblom B. Effects of dietary nitrate on oxygen cost
during exercise. Acta Physiol. 2007;191(1):59-66.
11. Masschelein E, Van Thienen R, Wang X, Van Schepdael A,
Thomis M, Hespel P. Dietary nitrate improves muscle but not cerebral
oxygenation status during exercise in hypoxia. J Appl Physiol.
2012;113(5):736-745.
12. Murphy M, Eliot K, Heuertz RM, Weiss E. Whole beetroot
consumption acutely improves running performance. J Acad Nutr Diet.
2012;112:548-552.
13. Vanhatalo A, Bailey SJ, Blackwell JR, et al. Acute and
chronic effects of dietary nitrate supplementation on blood pressure and the
physiological responses to moderate-intensity and incremental exercise. Am J
Physiol Regul Integ Comp Physiol. 2010;299:R1121-R1131.
14. Vanhatalo A, Fulford J, Bailey SJ, et al. Dietary
nitrate reduces muscle metabolic perturbation and improves exercise tolerance
in hypoxia. J Physiol. 2011;589:5517-5528.
15. Wilkerson DP, Hayward GM, Bailey SJ, et al. Influence of
acute dietary nitrate supplementation on 50 mile time trial performance in
well-trained cyclists. Eur J Appl Physiol. 2012:doi:10.1007/s00421-021-2397-6.
16. Bailey SJ, Vanhatalo A, Winyard PG, Jones AM. The
nitrate-nitrite-nitric oxide pathway: Its role in human exercise physiology. Eur
J Sport Sci. 2011;12:309-320.
By: Lauren Gesslein-Hausheer, Craig Hempel, Kim Ly Nguyen, Libby Quincy, & Maren Wolff
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