A Glass Of Beetroot Juice Is Great For Reducing Blood Pressure

♦ Beetroot juice shown through research helps to reduce blood pressure by up to 7%

♦ High levels of nitrate believed to be responsible

♦ Great for sports people too as a form of nitrate supplementation

Overview

Beetroot juice is a recent beverage receiving much attention for its health benefits. Athletes are taking the juice as a natural form of nitrate supplementation to improve both muscle performance and cell function. Recent research evidence also indicates a daily glass could reduce blood pressure by up to 7% because of its high nitrate level which is about 143mg/100g of juice. I wondered what it tasted like?  Having tried a sample of Organic ‘Beet It’ last time at the IFE 2011, I was pleasantly surprised at how palatable the drink was even though it has a distinctive flavour and aroma. It was not overtly sweet or had the vegetable notes associated with other juices in this genre. Beetroot used to be synonymous with colouring food a dark plum red when offered as a side dish and largely fell out of fashion because of this. However, playing on the strong colour-the betalaines, gives the customer an alternative to the potent anthocyanins found in fruit juices for example.

There are some very useful web-sites which look at ways of using beetroot. Try http://www.beetrootrecipes.co.uk/ for example which has some really useful recipes as well as extolling the vegetables’ benefits. We also have a page which describes how this vegetable can be grown (page: Growing Beetroot).

In Northern Europe, beetroot is commonly cultivated and eaten raw, boiled and even fermented, where it is added to salads or used to prepare the soup ‘borscht’. It has a high nutrition value being a source of fibre, folic acid and minerals. Betalain too has its own antioxidant properties (Kujala et al., 2002) and are split into two types, betacyanins and betaxanthins. A recent study looked at optimising the extraction of these colouring materials (De Azeredo et al., 2009).Processing the juice follows conventional methods based on crushing, pressing, a clarification using membranes or decanters and thermal evaporation to concentrate the juice. The physical properties of the juice and concentrate have been characterised i.e. viscosity and other temperature –related flow parameters (Juszczak et al., 2010).

There are studies investigating the combination of clarification and subsequent membrane concentration using a combination of microfiltration followed by ultrafiltration to achieve a brix of 25. Enzyme treatment to remove pectins and other large polymers is essential if permeate flux rates are to be commercially achievable. The concentrate on dilution was found to be similar to the feedstock (Thakur and Gupta, 2006) although there is likely to be a difference in flavour between thermal and non-thermally processed juices on reconstitution to single-strength.

Food Use

The concentrate is approved for use as a food colourant (E 162). The colouring is due to betalains which are a very stable class of pigments used primarily in snacks or other low-acid to neutral foods. The juice but also contains nitrate which has been shown in certain studies to reduce hypertension (blood pressure) and thus help cut the risk of cardiovascular disease and stroke (Larsen et al., 2006).

Studies On Blood Pressure With Beetroot Juice

It’s understood that 16 million people in the UK alone have high blood pressure and is a major risk factor for heart and kidney disease.   A normal person would have a blood pressure  of 140/90 mm Hg and any values higher begins to constitute hypertension.  A recent study conducted at the Queen Mary University, London found that drinking a glass (250ml  [about 8 oz.] ) of juice a day when compared to taking nitrate tablets produced similar beneficial effects (Kapil et al., 2010). They recruited 8 women and 7 men with high blood pressure but not taking drugs for it who drank a glass of juice compared to the placebo of water with some nitrate. Blood pressure was lowered after 24 hours by up to 10 mmHg, following imbibing but was a short-term effect. The optimum reduction was between 3 and 6 hours after drinking the juice.In the body, the nitrate is converted into nitric oxide which causes blood vessels to widen and thus lower blood pressure (Gilchrist et al., 2011). The study was a randomised, crossover trial but involved only a small number of healthy subjects with normal blood pressure. There is a very potent commentary on the study itself reported on the NHS web-site which seeks to place the study in context (NHS, 2011). It’s also found in sports supplements as eating beetroot is thought to improve blood flow to the brain and  improve training stamina.

One study by researchers at the Howard University Hospital in Washington D.C. on obese African-American women compared the effect of drinking orange juice as the placebo versus beetroot juice as an active treatment on a number of healthy heart related factors. Drinking beetroot juice increased plasma nitric oxide concentration, decreased oxygen consumption, systolic blood pressure, and heart rate at various levels of peak oxygen consumption  (Bond et al., 2013).

Perhaps one of the greatest benefits applies to patients with heart failure, who have impaired exercise capacity and lower quality of life. The muscle dysfunction in patients who have suffered heart failure may be due to a decrease in nitric oxide bioavailability. A study of beetroot juice supplementation in patients with heart problems found that acute consumption produced a 10% increase in their knee extensor power (Coggan et al., 2015).

Safety Levels On Beetroot Juice

Official nutrition bodies have looked at the levels of nitrate in the diet from a safety point of view too. The JECFA European Commission’s Scientific Committee on food has set the acceptable daily intake (ADI) at up to 3.7 mg/kg body weight which amounts to about 260mg per day for a 70.6kg person. The US Environmental Protection Agency (EPA) have decided on a Reference Dose which is nearly twice this level.

Although inorganic nitrate (NO3- ) is regarded as a potentially toxic material (Tannenbaum and Correa, 1985) there is a pathway where nitrate is converted into more useful biochemical agents (Lundberg et al., 2009, 2011). It’s also found in other vegetables such as celery (>250mg/100g) and spinach (up to 390mg/100g). Continuous production of nitric oxide maintains vascular tone and is generally produced by enzymatic oxidation using endothelial NO synthase, of the amino-acid L-arginine. Studying this pathway has been particularly rewarding for researchers hoping to understand much more about mechanisms that help heart function. Lansley et al., (2011b) also hinted that beetroot, with its high content of polyphenols such as resveratrol and quercetin might also enhance aerobic capacity at the mitochondrial level.  

Beetroot Juice For Sports People

For the sports person, the benefits are considerable.  A number of studies indicate that the high performance or elite athlete can improve power output relative to oxygen intake following brief periods of nitrate consumption, up to 700mg nitrate drinking either beetroot juice or a supplement (Vanhatalo et al., 2010; Larson et al., 2007). Another study showed that drinking juice could help endurance athletes such as cyclists increase their exercising time by 16% (Lansley et al., 2011a). As with many studies of this nature, more longer-term research is required. One particular element is to understand if there is a dose-related context to the benefits seen with drinking beetroot juice. Likewise, nitrates are beneficial for the well-trained athlete but what about the average sports person ? Would other forms of beetroot, pickled beetroot for example be as beneficial as well as the raw vegetable commonly eaten in salads ?

References 

De Azeredo, H.M.C., Pereira, A.C., de Souza, A.C.R., Gouveia, S.T. Mendes, K.C.B. (2009) Study on efficiency of betacyanin extraction from red beetroots. Inst. J. Food Science Technol., 44 pp. 2464-2469
Gilchrist, M., Shore, A.C., Benjamin, N. (2011) Inorganic nitrate and nitrite and control of blood pressure. Cardiovasc. Res. 89(3) pp. 492-498
Juszczak, L., Witczak, M., Fortuna, T., Solarz, B. (2010). Int. J. Food Prop. 13 (6) DOI: 10.1080/10942912.2010.490896
Kapil, V., Milsom, A.B., Okorie, M., Maleki-Toyserkani, S. et al. (2010) Inorganic nitrate supplementation lowers blood pressure in humans: Role for nitrite-derived NO. Hypertension 56 pp. 274–281.
Kujala, T., Vienola, M.S., Klika, K.D.  Loponen, J.M., Pihlaja, K. (2002) Betalanin and phenolic compositions of four beetroot (Beta vulgaris) cultivars. Eur. Food Res. Technol.  214, pp. 505–510.
Lansley, K.E., Winyard, P.G., Bailey, S.J. et al., (2011a) Acute dietary nitrate supplementation improves cycling time trial performance. Med. Sci. Sports Exerc. 43 (6) pp. 1125-1131
___________________., Fulford, J., Vanhatalo, A., Bailey, S.J., Blackwell, J.R., DiMenna, F.J., Benjamin, N. Jones, A.M. (2011) Dietary nitrate supplementation reduces the O2 cost of walking and running: a placebo-controlled study. J. Appl. Physiol. 110 pp.591-600
Larsen FJ, Ekblom B, Sahlin K, Lundberg JO, Weitzberg E (2006) Effects of dietary nitrate on blood pressure in healthy volunteers. N. Engl. J. Med. 355 pp. 2792–2793.
Lundberg, J.O., Gladwin, M.T., Ahluwalia, A., et al. (2009) Nitrate and nitrite in biology, nutrition and therapeutics. Nat. Chem Biol 5 pp. 865–869.
____________, Carlstrom, M., Larsen, F.J., Weitzberg, E. (2011) Roles of dietary inorganic nitrate in cardiovascular health and disease. Cardiovasc. Res. 89 (3) pp. 525-532
NHS (2011) Post: Beetroot juice for blood pressure. http://www.nhs.uk/news/2010/06June/Pages/Beetroot-juice-and-blood-pressure.aspx sourced 28th September 2011. 12.21 a.m. GMT
Santamaria, P. (2006) Nitrate in vegetables:toxicity, content, intake and EC regulation. J.Sci.Food Agric. 86 pp. 10-17
Tannenbaum S.R., Correa, P. (1985) Nitrate and gastric cancer risks. Nature 317 pp. 675–676.
Thakur, V. Gupta, D.K.D. (2006) Studies on the clarification and concentration of beetroot juice. J. Food Proc. Preserv. 30(2) pp. 194-207
Vanhatalo, A., Bailey, S.J., Blackwell, J.R., DiMenna, F.J., Pavey, T.G., Wilkerson, D.P. Benjmamin, Winyard, P.G., Jones, A.M. (2010) Acute and chronic effects of dietary nitrate supplementation on blood pressure and the physiological responses to moderate-intensity and incremental exercsie. Am. J. Physiol. Regal., Integr., Comp., Physiol. 299 R1121-1131

Revised 23rd July 2017