The beetroot (Beta vulgaris) is a root vegetable, part of the Chenopodiaceae family of plants (1), whose chemical composition has been object of study for improving the sport performance of athletes.
Inorganic nitrate (NO3) quantities found in beetroot juice and its dosage
Most available evidence points out that increased sports performance is a result of the presence of inorganic nitrate (NO3) and the enzymatic transformations under which this molecule is transformed (2-3). Inorganic nitrate is present in beetroot juice in about 110 to 3670 mg per kg of beetroot (which is particularly high for any food anyway), and the quantity of beetroot juice which has been utilised in different clinical trials is variable but the use of 500 ml is more or less the standard for an effective supplementation (4).
High intensity interval training evaluated through beetroot juice: Nitric oxide
A review article written by Domínguez et al., evaluated the available evidence on the potential of beetroot juice to improve high-intensity intermittent exercise performance (2). Most available evidence pointed out that beetroots contain a significant amount of inorganic nitrate, and that this is one of the most important metabolites that participate in performance improvements (2). Inorganic nitrate (NO3), serves as a substrate or a starting point for other enzymes present in the human body to act upon and transform NO3 into nitric oxide (NO) (2). NO and other derivatives which are also made in the human body, have different effects along the different receptors available for this compound among cells, and one of its main targets is blood vessel dilation (2). This dilation allows for more blood to reach more human cells, allowing for a higher oxygen and other metabolites uptake, and finally resulting in better cellular metabolism and improved overall muscular performance (2).
Cardiorespiratory endurance is defined as the ability of respiratory and circulating systems to adequately satisfy cellular metabolism under exercise-like conditions (3). Unlike high intensity interval training, cardiorespiratory endurance is characterised mainly by cellular metabolism which depends on oxygen-present conditions and metabolic pathways which are more favoured in their metabolic relevance, when oxygen is present (3). Just like in high-intensity interval training, inorganic nitrate (NO3), is the relevant compound found in beetroot juice which improves exercise performance, or at least, it is the compound which has the most extensive research aiming to demonstrate its efficacy under these circumstances (3). As mentioned before, inorganic nitrate goes through a series of chemical transformations which end up converting it into the active metabolite named nitric oxide (NO) (3). NO allows for vasodilation to occur and thus, for more oxygen to reach more muscular cells, allowing for better exercise performance and a higher threshold for fatigue (3). A systematic review, aimed to assess the efficacy of beetroot juice supplementation on cardiorespiratory endurance, which lasts for more than five minutes and as mentioned before, depends primarily on aerobic metabolism, pointed out that beetroot juice supplementation can increase efficiency, better performance in exercises of different distances, reduces exhaustion allowing for larger periods of time of non-stop exercise (3). It is important to understand that beetroot juice, could also diminish the negative effects of hypoxia (oxygen-deprived situations), which are often the cause of prolonged recovery and impairs efficiency in athletes.
Muscle recovery is of particular importance in any exercise or sport regardless of its metabolism (oxygen-dependent or not); beetroot juice may allow for a faster muscle recovery time and increased efficiency (3).
- Showing all polyphenols found in Red beetroot, raw – Phenol-Explorer [Internet]. Phenol-explorer.eu. [cited 23 May 2021]. Available from: http://phenol-explorer.eu/contents/food/499
- Domínguez R, Maté-Muñoz J, Cuenca E, García-Fernández P, Mata-Ordoñez F, Lozano-Estevan M et al. Effects of beetroot juice supplementation on intermittent high-intensity exercise efforts. Journal of the International Society of Sports Nutrition. 2018;15(1).
- Domínguez R, Cuenca E, Maté-Muñoz J, García-Fernández P, Serra-Paya N, Estevan M et al. Effects of Beetroot Juice Supplementation on Cardiorespiratory Endurance in Athletes. A Systematic Review. Nutrients. 2017;9(1):43.
- Siervo M, Lara J, Ogbonmwan I, Mathers J. Inorganic Nitrate and Beetroot Juice Supplementation Reduces Blood Pressure in Adults: A Systematic Review and Meta-Analysis. The Journal of Nutrition. 2013;143(6):818-826.