Beetroot (Beta vulgaris) and beetroot juice have become increasingly popular health foods in societies across the world and amongst subpopulations such as athletes aiming to improve their sports performance. This has been fueled by a growing interest in the biological activity of red beetroot and its potential utility as a disease-preventing functional food for health promotion.
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Beetroot is among a variety of edible taproots that are sourced predominantly in the Middle East but has spread to Europe Asia and the Americas. The health promotional characteristics of beetroot include antioxidant and anti-inflammatory effects, anti-diabetic and anti-carcinogenic and hypertensive, hepatoprotective, and wound healing properties.
Recent studies on beetroot supplementations have emphasized the attributional role of inorganic nitrate (NO3) in the clinical effect that it, and its by-products, produce.
The nutritional and bioactive capacity of beetroot
Beetroot is comprised of several biologically active phytochemicals which include betalains, flavonoids (tiliroside, astragalin, rhamnocitrin, rhamnetin, kaempferol), polyphenols, and saponins, among NO3. The functional effects of nitrate in the body are mediated through its in vivo reduction to nitric oxide (NO), a multi-functional messenger molecule that has implications in the vascular and metabolic systems.
Beetroot also contains a profile of B-vitamins B1- thiamine, B2-riboflavin, B3-niacin, B5-pantothenic acid, B6-pyridoxine, B9-folates, and B12-cyanocobalamin) as well as folic acid. The protein profile of beetroot is also notable and is comprised of several essential amino acids. Beetroot is also a highly potent source of a range of minerals which include phosphorus, calcium, magnesium, copper, zinc, iron, potassium, sodium, and manganese.
The consumption of beetroot is equally as diverse and includes consumption in the form of a whole food (boiled, roasted, pickled, pureed, or raw), powder, juice, gel, bread, or jam. 100ml of beetroot juice provides 95 Kcal, of which the macronutrient profile includes 22.6g carbohydrate, 0.7g protein, 0.16g lipid, 0.91g total dietary fiber, and 12g total sugars.
The health benefits of fibre derived from beetroot
The fiber content in beetroot producers a probiotic effect, increasing the proportion of beneficial bacteria, such as Bifidobacterium and Lactobacillus species.
Sugar beet pectin has also been found to modulate microbial gut communities, skewing communities and species to produce a more beneficial composition. This results in the production of bacterial metabolites, namely SCFA, which are implicated in a variety of beneficial effects in the body.
The nicronutrient content of beetroot
Considering micronutrients, conventional beetroot is reported to contain vitamin C and total flavonoids within a range of 10.75–20.36mg and 2.02–2.36mg per 100g respectively. Betalains comprise between 70 and 100% of the phenolic composition which is split between betacyanins and betaxanthins in a 60:40 ratio.
As such, beetroot is classified as one of the top ten plants with the highest antioxidant activity, providing the majority of commercially produced betalains in their concentrated form. Unlike flavonoids, which change vegetable processing, polyphenols retain their activity after in vitro processing. Interestingly, polyphenols are found in the highest ratio in gel format as compared to others including beetroot juice.
Although nitrate is inert, it is capable of being enzymatically altered to produce NO2 and NO through bacterial pathways via NO3 reductase.
Beetroot also contains oxalic acid, which functions as a metal ion chelator, and promotes the formation of nephroliths (kidney stones) As such, beetroots are a health concern, predominantly for patients predisposed to kidney disease.
Owing to the majority of the health effects of beetroot being attributed to NO3, NO3-rich beetroot supplements and other methods of concentrating this compound have been introduced. Among beetroot products, beetroot chips contain the highest energy content, carbohydrate, and total sugar as well as the highest value of Total Antioxidant Potential and the lowest value of Total Phenolic Content, saponin, and flavonoids.
Gel, conversely, is the preferred means of nitrate administration in athletes particularly as it contains the lowest lipid content highest protein content, and is therefore considered the most effective formulation of beetroot.
The effects on blood pressure and vascular function
Several studies have corroborated the impact of both acute and long-term beetroot juice consumption on blood pressure and vascular function. Meta-analyses of several studies reveal that beetroot overwhelmingly lowers blood pressure among both hypertensive and normotensive (normal blood pressure) individuals who have varied levels of health.
The mechanistic link between the blood pressure-lowering properties of beetroot is commonly attributed to the role of NO3. Many studies have corroborated this finding, demonstrating vasodilator properties and changes in the microvasculature after the consumption of NO3-rich beetroot juice.
What effect do beetroot-derived betalains have on the body?
Betalains are a class of red and yellow pigments derived from tyrosine, which are rich in nitrogen. They are a focus of much research owing to their bioactivity, which ranges from antioxidant capacity, immune system performance-boosting, protection against cardiovascular and neurodegenerative disorders, and cancer chemoprevention.
In the context of antioxidation, betalains increase cellular resistance to oxidation, decreasing the oxidative damage of lipids. They function to reduce the extent of inflammation in blood vessels, joints, and bones.
Mechanistically, this enriches human low-density lipoprotein and myoglobin. Consequently, betalains help to regulate oxidative stress-related disorders and have implications in diseases associated with oxidative stress and inflammation.
What are the health-promoting properties of organic acids in beetroot?
Beetroots are abundant in organic acids period of them phosphoric and citric acids are the most prevalent, followed by oxalic acid and malic acid. The precursor for the synthesis of our aromatic amino acids is shikimic acid, and this is also detected at high concentrations in beetroot.
Malic acid functions as an adjunct in calcium renal stone disease as it can complex with calcium ions in urine to prevent the formation of calcium oxalate, the main constituent of kidney stones. Similarly, citric acid reduces predisposition to renal stone formation.
Ascorbic acid, or vitamin C, is a powerful antioxidant. It can donate a hydrogen atom to generate the free ascorbyl radical to protect biomolecules from damage caused by oxidative compounds which are produced as a by-product of cell metabolism.
Vitamin C also operates as a cofactor for mono- and di-oxygenase enzymes which are implicated in the breakdown of toxins and pollutants. Similarly, vitamin C is also a cofactor for procollagen enzymes which generate substrates for collagen biosynthesis, and also stabilizes collagen through intermolecular collagen crosslinked formation.
Succinic acid act via several growth factors to promote angiogenesis. In addition to this succinate activates succinate two receptor one signaling, which promotes the production of under filial nitrogen oxide and prostaglandin E2, and the release of renin. The renin-angiotensin system is a major control system for blood pressure and fluid balance; as such, succinic acid supports NO3 vascular effects.
The mineral content of beets is also essential to the health-promoting benefits of beetroot. Potassium is essential for muscle and nerve function and works to reduce muscular dependence on adenosine triphosphate, the body’s source of energy.
Overall, beetroot has a widespread effect on the body. It exerts its greatest effect on the cardiovascular system owing to its high concentration of nitrates. Its anti-cancer and anti-inflammatory properties are attributed to its high concentration of phenolic compounds and organic acids which work in tandem to protect cells from oxidative damage, a process implicated in several diseases and cancer.
Collectively, betalains and phenolics with antioxidant, anti-inflammatory, and anti-carcinogenic properties have been linked to the positive effects of beetroot on health.
- Mirmiran P, et al Functional properties of beetroot (Beta vulgaris) in management of cardio-metabolic diseases. Nutr Metab (Lond). 2020;17:3. doi:10.1186/s12986-019-0421-0.
- Clifford T, et al. The potential benefits of red beetroot supplementation in health and disease. Nutrients. 2015;7(4):2801-2822. doi:10.3390/nu7042801.
- Kavitha Ravichandran, Iryna Smetanska, Usha Antony.Chapter 19 - Red beet. In: Amit K J (Ed). Nutritional Composition and Antioxidant Properties of Fruits and Vegetables. Academic Press; 2020, (pp.315-321). doi:10.1016/B978-0-12-812780-3.00019-2.