BEETROOT JUICE - LEGAL DOPING FOR ATHLETES?

Nitric oxide (NO) is a physiologically important signaling molecule that promotes the expansion of blood vessels and thus facilitates the transport of oxygen (O2) and energy substrates to the muscles. Research shows that nitric oxide (NO) also improves the effectiveness of mitochondrial respiration, which is manifested by reduced oxygen consumption during exercise. Until recently, it was thought that nitric oxide (NO) could only be formed as a result of the endogenous pathway of oxidative transformations L-arginine. Recent research results indicate, however, that an alternative to the endogenous pathway of nitric oxide (NO) formation may be the exogenous supply of inorganic nitrates (NO₃-) with food. The aim of the study was to review the current literature on the properties of beetroot juice as an important source of nitrates (NO₃-) and its effectiveness in improving the exercise capacity of physically active people. A systematic review of the research, published from 2005 to January 31, 2021, was made on the basis of searching bibliographic databases such as: PubMed, Elsevier and Web of Science. The following keywords were used: "beetroot", "beetroot juice", "nitrates", "nitrites", "nitric oxide", "supplementation", "ergogenic substances", "sports nutrition". Although there are conflicting data, it appears that beetroot juice supply may be a cheap, natural, and promising nutritional strategy for improving sports performance in both endurance and intermittent high intensity (start-stop) exercise. More detailed studies are analyzing the effect of dietary nitrate (NO₃-) supply in anaerobic exercise - especially in high-volume resistance training - are needed. It is also emphasized that further research is needed to elucidate the effects of specific factors on the variability of ergogenic effects after beetroot juice consumption, which may be of the greatest importance in terms of the effectiveness of this nutritional intervention. [ABSTRACT FROM AUTHOR]