Beet Juice: A Summary of Health and Performance Effects
Intro to Beet Juice
Beet juice is extracted from the common taproot vegetable beetroot from the beet plant (Beta vulgaris). Beets also contain several subspecies used for fodder, sugar, and food.
Beetroot is a nutrient-dense food containing a range of vitamins and minerals; carotenoids (pro-vitamin A) vitamins B1, 2, 3, 5, 6, and 9, C, sodium, calcium, iron, phosphorous, potassium, magnesium, and zinc. It is especially rich in an array of antioxidant polyphenols, betanin and betalain which are the primary pigments providing the deep rich red colour of beets and used as a dye and food colour.  These pigments, and the various phytochemicals from beets have been demonstrated (mostly in animal research) to reduce oxidative stress, increase endogenous antioxidant activity, reduce inflammation, and protect LDL-cholesterol from oxidation. 
Beetroot is most well-known though as a provider of high amounts of dietary nitrates. These nitrates can be converted to nitric oxide, a molecular signal for vasodilation. Dietary nitrates, especially those from beet juice have demonstrated benefits to physical performance, blood pressure, and endothelial function and are suggested to have additional benefits to gut and brain health.
This summary focusses on reviews of clinical trials on nitrate-rich beet juice supplementation.
Beet juice and exercise performance & physical function
Beetroot juice increases levels of nitric oxide which is a signalling molecule that helps regulate blood flow, gas exchange, mitochondrial biogenesis and efficiency, and muscular contraction.
In a review of 23 trials, while results are conflicting, overall results suggested beetroot juice supplementation can improve cardiorespiratory endurance (by increasing efficiency) and increase time to exhaustion in submaximal exercise. It may also improve the cardiorespiratory performance at anaerobic threshold and maximal intensity bouts of exercise. 
In a 2020 review by Rojas-Valverde et al., 7of 18 included studies showed benefits to repeat sprint performance across measures including peak power, mean power, sprint time, time to failure, repetitions performed, fatigue, and total work performed.  Despite some negative effects seen in studies and some participants, the studies that noted improvements in measures of sprint performance were meaningful and would result in drastically different competition results for those athletes for whom there is a benefit. For example, the nearly 2% improvement in sprint time seen by Buck et al. (2015) and cited in this review.
Several factors could influence the variability in results from performance research including the different demands of sports or activities tested (especially their differing neuromuscular demands), the dosage used, baseline nitrate intake from diet, and the skill level of the athletes tested.
While no overall effect was seen on cardiovascular events or measures in people with chronic obstructive pulmonary disease, there was a significant improvement in perceived exertion in those taking beet juice compared to placebo. 
Beet juice and blood pressure
Beetroot juice supplementation is associated with ~ 4 mm Hg reduction in systolic blood pressure, with smaller (and equivocal) reductions in diastolic blood pressure. [5, 6] Doses used in the research reviewed by Siervo and colleagues and published in The Journal of Nutrition ranged from 5.1 to 45 mmol/dose (321–2790 mg) with greater effects seen from larger doses.  A later (2018) review found greater effects (5 and 12 mmHg of SBP and between 5 and 6 mmHg of DBP) suggestive of a 14–38% reduction in cardiovascular disease mortality and the greatest effects observed with longer durations of supplementation (i.e. ≥ 2 weeks). This review also suggested there might be a lower response in older adults and women, but this is unclear as there are fewer studies including these populations. 
Beet juice and endothelial function
A review of the effects of beet juice supplementation (1.5 to 28 days) on endothelial function, including 9 crossover and 3 parallel trials, showed a significant dose-dependent effect on vascular function. However, the authors noted “These effects appear to be reduced in older subjects and subjects with greater cardiometabolic risk”. 
Beet juice and gut health
Beets contain a range of bioactive compounds associated with gut health including fibre, pectic-oligosaccharides, and betalains and polyphenols. Beet extracts and pectin (a dietary fibre) and pectic-oligosaccharides are bifidogenic and positively affect the human gastrointestinal microbiota. Betalains and polyphenols appear to increase metabolites of the human microbiota including short-chain fatty acids that are beneficial to health. 
Beet juice and neurodegenerative diseases
Reduced circulation in the brain is a characteristic of neurodegenerative disorders such as Alzheimer’s disease. Dietary nitrates found in abundance in beet juice help to improve circulatory activity in the brains of people with Alzheimer’s, while the betanin compounds in beets help to reduce the accumulation of dysfunctional, misfolded proteins in ND disorders (beta-amyloid plaques and Tau proteins). It is thought that this occurs due to reduced oxidation of the mineral-linked beta-amyloid proteins which inhibited folding abnormalities. In a rat model of Parkinson’s disease, beetroot (100–300 mg/kg) helped protect against behavioural changes, possibly through antioxidant and/or dopaminergic activity. 
Beet juice and cancer
Betanin treatment has reduced cancer incidence and growth in vitro and in vivo in animals. 
Beet juice and high nitrate beet juice supplements are commonly used by athletes and for certain health conditions. Based on the available evidence beet juice reduces systolic blood pressure and may help to modulate blood pressure overall and is likely to have other benefits to vascular function and the health of the gut microbiota.
Performance benefits have been observed in many studies for both endurance and sprint performance but the effects (esp. for sprint performances) are variable. Dose, sport, diet, and individual variability are all likely to affect the efficacy of beet supplementation for an athlete. So, it is suggested that athletes try beet supplementation in tests of competition to gauge whether there is a benefit for them specifically.
How to use:
For health outcomes: Eat a vegetable-rich diet and supplement with 1 x high-nitrate beet shot or drink a large glass of beet juice daily.
For performance: 2 shots of high-nitrate beet juice for 3–6 days before an event (inclusive of the event day) 
Example: Beet-It beet juice shots by James White foods contain a standardised, concentrated amount of nitrate (~400 mg). These have been used in many studies of beet supplementation and are considered the ‘gold standard’.
1. Hadipour E, Taleghani A, Tayarani-Najaran N, Tayarani-Najaran Z. Biological effects of red beetroot and betalains: A review. Phytotherapy Research. 2020;34(8):1847–67.
2. Domínguez R, Cuenca E, Maté-Muñoz JL, García-Fernández P, Serra-Paya N, Estevan MCL, et al. Effects of Beetroot Juice Supplementation on Cardiorespiratory Endurance in Athletes. A Systematic Review. Nutrients. 2017;9(1):43.
3. Rojas-Valverde D, Montoya-Rodríguez J, Azofeifa-Mora C, Sanchez-Urena B. Effectiveness of beetroot juice derived nitrates supplementation on fatigue resistance during repeated-sprints: a systematic review. Critical Reviews in Food Science and Nutrition. 2020:1–12.
4. Alshafie S, El-Helw GO, Fayoud AM, Elrashedy AA, Gbreel MI, Alfayoumi SS, et al. Efficacy of dietary nitrate-rich beetroot juice supplementation in patients with chronic obstructive pulmonary disease (COPD): A systematic review and meta-analysis. Clinical Nutrition ESPEN. 2021;42:32–40.
5. Siervo M, Lara J, Ogbonmwan I, Mathers JC. Inorganic Nitrate and Beetroot Juice Supplementation Reduces Blood Pressure in Adults: A Systematic Review and Meta-Analysis. The Journal of Nutrition. 2013;143(6):818–26.
6. Bahadoran Z, Mirmiran P, Kabir A, Azizi F, Ghasemi A. The Nitrate-Independent Blood Pressure–Lowering Effect of Beetroot Juice: A Systematic Review and Meta-Analysis. Advances in Nutrition. 2017;8(6):830–8.
7. Bonilla Ocampo DA, Paipilla AF, Marín E, Vargas-Molina S, Petro JL, Pérez-Idárraga A. Dietary Nitrate from Beetroot Juice for Hypertension: A Systematic Review. Biomolecules. 2018;8(4):134.
8. Lara J, Ashor AW, Oggioni C, Ahluwalia A, Mathers JC, Siervo M. Effects of inorganic nitrate and beetroot supplementation on endothelial function: a systematic review and meta-analysis. Eur J Nutr. 2016;55(2):451–9.
9. de Oliveira SPA, do Nascimento HMA, Sampaio KB, de Souza EL. A review on bioactive compounds of beet (Beta vulgaris L. subsp. vulgaris) with special emphasis on their beneficial effects on gut microbiota and gastrointestinal health. Critical Reviews in Food Science and Nutrition. 2020:1–12.