The Potential Benefits Beetroot Extract Supplementation in Health and Disease
The recent interest in beetroot extract has been primarily driven by the discovery that sources of dietary nitrate may have important implications for managing cardiovascular health.
Recent studies have provided compelling evidence that beetroot extract ingestion offers beneficial physiological effects that may translate to improved clinical outcomes for several pathologies, such as; hypertension, atherosclerosis, type 2 diabetes and dementia. Hypertension in particular has been the target of many therapeutic interventions and there are numerous studies that show beetroot, delivered acutely as a juice extract supplement significantly reduce systolic and diastolic blood pressure.
Beetroot’s effect on the vasculature is largely attributed to its high inorganic nitrate content. Nitrate itself is not considered to mediate any specific physiological function; rather, nitrates beneficial effects are attributed to its in vivo reduction to nitric oxide (NO), a multifarious messenger molecule with important vascular and metabolic functions.
Nitrate delivered via a beetroot extract source is metabolised to nitrite, which can be further reduced to produce NO. The conversion of nitrite to NO can be catalysed by many molecules with reductase potential (i.e., electron donors), and to date, several proteins (i.e., deoxymyoglobin, xanthine oxidoreductase) and antioxidants (i.e., vitamin C) have been reported to facilitate this reduction. One of the most important functions of endogenous NO is to maintain endothelial function. The endothelium plays a critical role in the regulation of vascular homeostasis by maintaining thrombotic activity, platelet function, vascular tone and the delicate balance between the release of vasodilating (i.e., NO, prostacyclin) and vasoconstricting agents (i.e., endothelin-1, thromboxane). Because NO mediates many of the endothelium’s functions, a depletion in NO availability, as seen with aging, has been singled out as the principal cause of endothelial dysfunction. Endothelial dysfunction is proposed as a primary risk factor for several cardiovascular disorders and has been implicated in the pathogenesis of hypertension and atherosclerosis. Therefore, beetroot extract, as a natural NO donor, has been explored as a nutritional approach to preserve or restore endothelial function.
Webb et al. were the first to investigate the effects of a beetroot extract supplement on endothelial function in healthy participants. They measured brachial artery (BA) endothelial function using the flow mediated dilation technique (FMD), which involved calculating BA dilation before and after a 20-min ischemic insult. The ischemic procedure (BA occlusion) was effective at inducing endothelial dysfunction, as evidenced by the 60% decrease from pre-to post BAFMD response. However, when participants were pre-treated 2 h prior with a single serving of beetroot juice (500 mL; 23 mmol of nitrate) the BAFMD response was maintained at pre-ischemic levels, suggesting that beetroot juice acted to preserve endothelial function.
Hobbs et al. extended these findings, examining the acute intake of a novel beetroot enriched bread (100 g beetroot, nitrate; 1.1 mmol) on micro vascular function and peripheral arterial stiffness in young healthy males. Although arterial stiffness, assessed by pulse wave velocity and augmentation index, was unaffected by the intervention, the beetroot bread increased micro vascular vasodilation, as measured by changes in cutaneous perfusion using laser doppler imaging (LDI). Endothelium-independent vasodilation (perfusion units) was ~343% greater in the 6 h after ingesting the beetroot enriched bread compared to the control bread. Importantly, this study provided evidence that even a small nitrate load (1.1 mmol) can augment marked improvements in intravascular function. Similar vascular effects were also reported in a study with older populations. Using apparently healthy but slightly obese, older participants (~61 years), Joris and Mensink, investigated whether beetroot juice supplementation would prevent postprandial impairments in BAFMD. In a randomized crossover design, BAFMD response fell by ~1.6% in the control condition, whereas after beetroot juice (140 mL, nitrate; 500 mg) the impairment was only ~0.4%, indicative of a beetroot-mediated protective effect on postprandial endothelial function.
However, nitrate is not the only constituent of beetroot extract proposed to have beneficial effects in health and disease. Beetroot is a rich source of phytochemical compounds that includes ascorbic acid, carotenoids, phenolic acids and flavonoids.
Studies report that beetroot, in the form of an extract supplement, protects against oxidative damage to DNA, lipid and protein structures in vitro. A study by Wootton-Beard and Colleagues suggests that a key mechanism by which beetroot extract exerts its antioxidant effects is by scavenging radical species.
Beetroot extract has emerged as a potent anti-inflammatory agent. At least part of its anti-inflammatory effects seems to be mediated by interfering with pro-inflammatory signalling cascades. The most important of these is the Nuclear Factor-Kappa B (NF-κB) cascade, as it directly activates and transcribes most gene targets that regulate and amplify the inflammatory response (i.e., cytokines, chemokines, apoptotic and phagocytic cells).This raises the possibility that betanin rich beetroot extract could exhibit anti-inflammatory effects to rival synthetic drugs.
Conclusion:
Based on the available data, beetroot extract concludes to be a powerful dietary source of health promoting agents that holds potential as therapeutic treatment for several pathological disorders. The powerful antioxidant, anti-inflammatory and vascular-protective effects offered by beetroot and its constituents have been clearly demonstrated by several in vitro and in vivo human and animal studies; hence its increasing popularity as a nutritional approach to help manage cardiovascular disease and cancer. In the human studies to date, beetroot supplementation has been reported to reduce blood pressure, attenuate inflammation, avert oxidative stress, preserve endothelial function and restore cerebrovascular haemodynamics.
REFERENCE SOURCE: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4425174/