Drinking beetroot juice can increase blood flow to the brain in older adults, potentially halting the progresses of dementia.
“There have been several studies showing that drinking beet juice can lower blood pressure, but we wanted to show that drinking beet juice also increases perfusion, or blood flow, to the brain,” said Daniel Kim-Shapiro, director of Wake Forest University’s Translational Science Center.
“There are areas in the brain that become poorly perfused as you age, and that’s believed to be associated with dementia and poor cognition,” Shapiro said.
Beetroot juice
High concentrations of nitrates are found in beets, as well as in celery, cabbage and other leafy green vegetables like spinach and lettuce, reports the journal Nitric Oxide: Biology and Chemistry.
When you eat high-nitrate foods, ‘good bacteria’ in the mouth turn nitrate into nitrite, according to a Wake Forest statement.
Research has found that nitrites can help open up the blood vessels in the body, increasing blood and oxygen flow.
In the study, researchers looked at how dietary nitrates affected a group of adults aged 70 and above.
The MRIs showed that after eating a high-nitrate diet for four days, blood flow to the white matter of the frontal lobes increased. This area is commonly associated with degeneration that leads to dementia and other cognitive conditions.
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Beetroot juice could energise the elderly to lead more active lives, says a new study.
In tests, they required less energy to carry out low-intensity exercises after drinking the juice. The amount of effort it took to walk was reduced by 12 percent.
This could allow the elderly to carry out tasks they might not otherwise attempt, said the researchers from the Exeter University, Britain, reports the Journal of Applied Physiology.
Beetroot juice widens blood vessels and reduces the amount of oxygen needed by muscles during activity, according to the Daily Mail.
As people age, or if they develop conditions that affect the cardiovascular system, the amount of oxygen taken in during exercise can drop dramatically.
Katie Lansley from the Exeter University said: “What we’ve seen in this study is that beetroot juice can actually reduce the amount of oxygen you need to perform even low-intensity exercise.”
A team from Exeter and the Peninsula College of Medicine and Dentistry gave subjects normal beetroot juice or juice with the nitrates removed.
Andy Jones from Exeter said: “Each time the normal, nitrate-rich juice was used, we saw a marked improvement in performance which wasn’t there with the filtered juice – so we know the nitrate is the active ingredient.”
It’s not only athletes who can benefit from beetroot juice’s performance enhancing properties – its physiological effects could help the elderly or people with heart or lung-conditions enjoy more active lives, suggests a new study.
The new study by researchers at the University of Exeter in conjunction with the Peninsula College of Medicine and Dentistry has revealed the physiological effects of drinking beetroot juice could help a much wider range of people.
In the latest study, the researchers looked at low intensity exercise and found that test subjects used less oxygen while walking – effectively reducing the effort it took to walk by 12pc.
Katie Lansley, a PhD student from the university”s Sport and Health Sciences department and lead author of the study, said: “As you get older, or if you have conditions which affect your cardiovascular system, the amount of oxygen you can take in to use during exercise drops considerably. This means that, for some people, even simple tasks like walking may not be manageable.
“What we”ve seen in this study is that beetroot juice can actually reduce the amount of oxygen you need to perform even low-intensity exercise. In principle, this effect could help people do things they wouldn”t otherwise be able to do.”
When consumed, beetroot juice has two marked physiological effects. Firstly, it widens blood vessels, reducing blood pressure and allowing more blood flow. Secondly, it affects muscle tissue, reducing the amount of oxygen needed by muscles during activity. The combined effects have a significant impact on performing physical tasks, whether it involves low-intensity or high-intensity effort.
So far the research on the impacts of beetroot juice has only been carried out on younger people who are in good health, but the researchers believe there is no reason why the effects of beetroot juice wouldn”t help others.
“While we haven”t yet measured the effects on the elderly or those with heart or lung conditions, there is the potential for a positive impact in these populations which we intend to go on and investigate further,” Katie Lansley added.
Beetroot juice contains high levels of nitrate. The latest study has proved that this is the key ingredient, which causes the increase in performance, rather than any other component of the beetroot juice.
Professor Andy Jones, the senior scientist on the study and a pioneer of research into beetroot juice, said: “In this study, we were able to use – for the first time – both normal beetroot juice and beetroot juice with the nitrate filtered out. Test subjects didn”t know which one they were getting. The drinks both looked and tasted exactly the same. Each time the normal, nitrate-rich juice was used, we saw a marked improvement in performance which wasn”t there with the filtered juice – so we know the nitrate is the active ingredient.”
The study has been published in the Journal of Applied Physiology.
“Beetroot juice boosts stamina by making muscles more fuel-efficient,” according to the Daily Mail.
The study behind this claim set out to test the theory that beetroot juice, a rich source of nitrates, can increase muscle stamina. It found that seven volunteers who drank half a litre of beetroot juice each day for a week doubled the amount of nitrate in their blood. When tested on an exercise bike, the rate at which their muscles used up energy and oxygen was found to be slowed.
Problematically, because of its small size and the short-term physiological measurements that were taken, this study is not strong evidence that beetroot juice can increase stamina. More research is needed.
Where did the story come from?
The study was carried out by researchers from the School of Sport and Health Sciences at the University of Exeter, and the Peninsula Medical School. No sources of funding are reported. The study was published in draft in the peer-reviewed Journal of Applied Physiology.
What kind of research was this?
The purpose of this study was to investigate further how a short-term diet of nitrate might result in muscles using less oxygen during exercise. The researchers had looked at this effect in previous studies and noted that people fed these diets seemed to have an improved tolerance of high-intensity exercise.
The researchers set up the study as a randomised crossover trial, an appropriate design for testing this sort of theory. The researchers used concentrations and volumes of chemicals designed to maximise the effect of nitrate on muscles. No side effects were reported except for the red colouration of urine (beeturia). Whether or not beetroot juice can be used as a natural nitrate supplement, and whether it is of benefit to athletes needs further testing.
What did the research involve?
This was a randomised, double-blind crossover study, in which seven male volunteers (aged 19-38 years) were asked to drink 500mls a day, for six days, of either a commercially available organic beetroot juice or a low-calorie blackcurrant juice cordial. The beetroot juice contained 5.1mmol of nitrate (NO3), while the control drink had negligible nitrate content.
None of the subjects were smokers or used dietary supplements. They were not told the true theory that was being tested, but that the aim was to compare the effect of two commercially available beverages on exercise.
The volunteers came to the laboratory on seven occasions over four weeks. On the first visit, blood samples were taken for tests of plasma nitrite (NO2) and blood pressure was measured. After initial testing, the participants were randomly allocated to either beetroot juice or blackcurrant juice. Following the first experiment, the groups were swapped around so that everyone was tested with each drink, in a random order. There was a 10-day wash-out period between each drink. On the last three days of each drinking period, subjects were asked to complete a series of low-intensity and high-intensity ‘step’ exercise tests to determine their response to exercise.
Before each test, subjects were asked to avoid coffee for six hours and alcohol for 24 hours. They were asked not to eat foods rich in nitrates for the duration of the study.
The subjects were tested at the same time of day with two different tests:
* A test of metabolism used in sports science called 31P-magnetic resonance spectroscopy (31P MRS). This is a special form of magnetic resonance imaging in which the concentrations of chemicals in the body, such as the phosphates involved in energy metabolism in muscles, can be directly measured. The researchers were interested in measuring phosphocreatine, also known as creatine phosphate (Pcr), as this provides a rapidly mobilised reserve of high-energy phosphates released during exercise.
* A test of oxygen uptake in the lungs (vO2) as a response to exercise. For this test, the participants cycled on an exercise bike while attached to a device that measured their CO2 output and oxygen intake.
What were the basic results?
The NO3 supplementation was well tolerated with no side effects. However, subjects did report beeturia and red stools consistent with previous studies.
On the last three days of the test periods (days four to six) the beetroot juice groups had a significant increase in plasma nitrite (a result of the breakdown of nitrate by the body).
There was difference in the results when low- and high-intensity exercise were compared. During exercise, phosphocreatine is used as an energy source, lowering its concentration in the muscles, and vO2 is increased as the lungs take in more oxygen. During low-intensity exercise, the beetroot juice slowed this reduction in muscle phosphocreatine concentration and the increase in O2. However, during high-intensity exercise, though this effect was still evident, the difference was not large enough to be statistically significant. After drinking beetroot juice, the participants could cycle for longer before feeling exhausted.
How did the researchers interpret the results?
The researchers conclude that the lower O2 use during exercise in the dietary NO3 supplementation group appears to be due to a reduced use of adenosine triphosphate (ATP), a fuel used in muscles. They observe that this could mean that high-intensity exercise could be tolerated for a longer period.
Conclusion
This small experimental study appears to be well designed and reported. There are a few general points to note about this type of study:
* Although randomisation occurred, in a crossover study all participants receive both active beetroot juice and the placebo. This means that only the order in which the drinks were received was randomised.
* The fact that beetroot juice and blackcurrant juice taste different and that beetroot juice makes the urine go red means that the participants would have been aware of which drink they were taking and, therefore, were not really effectively blinded to the treatment. They could also have been aware of the supposed properties of beetroot juice.
* The effects in women were not tested and the athleticism of the volunteers is not reported.
* Beetroot juice is a rich source of nitrates, but there may be other differences between beetroot juice and low calorie blackcurrant cordial, such as sugar levels, which may affect how the body responds to exercise.
Overall, this physiological study in a small group of volunteers will be of interest to sports scientists working in the area. However, this is a small study and, until further research is carried out in larger groups, it does not provide a reason to start drinking beetroot juice to increase stamina.
“A daily glass of beetroot juice could combat the onset of dementia among older adults,” reported the Daily Express.
This news story is a based on a small study in 16 elderly people. The participants were given either a diet that was low or high in nitrates over a four-day period. Nitrates are present at high levels in beetroot and other vegetables, and converted into nitrites in the body, a chemical that is thought to increase blood flow. The participants’ blood flow to different regions of the brain was measured on a scan.
This was a small study conducted over an extremely short time span. Its findings suggest that adults who eat a diet high in nitrates may experience an increased blood flow to certain areas of the brain within a short interval, compared with eating a diet low in nitrates.
However, this does not mean that beetroot juice, or any other food high in nitrates, can help prevent dementia or even improve mental function. To investigate the role of any food or supplement in dementia would require a far larger study, tracking people over a much longer time.
Where did the story come from?
The study was carried out by researchers from Wake Forest University, Winston-Salem in the USA. It was funded by Wake Forest University and the National Institutes of Health. One of the researchers is also listed as co-author on a patent for the use of nitrite salts in the treatment of cardiovascular conditions. The study was published in the peer-reviewed journal Nitric Oxide: Biology and Chemistry. The press release reported that the university is currently looking into ways of marketing the juice.
What kind of research was this?
The researchers say poor blood flow and a restricted oxygen supply (hypoxia) around the body are causal factors in many health conditions and may be related to the decline in physical and cognitive function as people age. Previous research has shown that the chemical nitrite can widen blood vessels and increase blood flow and, as a result, it is being studied as a possible therapy for a wide variety of diseases.
Levels of nitrite in the blood can be increased by eating foods high in nitrate, such as beetroot, as nitrates are converted into nitrites in the body. The researchers maintain that nitrite has been found to have health benefits including a reduction in blood pressure, improvements in gut health and better exercise performance. This suggests that dietary nitrate could help in conditions caused by reduced blood flow, including dementia and cognitive decline.
The researchers also point out that a major feature of nitrite’s ability to increase blood flow is that in conditions caused by hypoxia, it increases blood flow in the areas where oxygen is needed most.
This laboratory study tested the effects of two different diets on blood flow to the brain, in a small group of older adults. It had a ‘within subject’ design, meaning that each participant was given both diets and the effects on their blood flow from each diet were compared. This was a preliminary study, involving only five adults, and the aim was to test the time taken for a high nitrate meal to be converted in the blood to peak levels of nitrite.
What did the research involve?
The research involved two studies. The preliminary study was aimed at exploring when blood levels of nitrate and nitrite reached peak levels following ingestion of nitrate. After an overnight fast, five adults aged 70 or older were given a high nitrate breakfast, including 500ml of beetroot juice. Researchers then drew blood after 30 minutes and at one-, two- and three-hourly intervals to determine blood levels of nitrate and nitrite.
In the main study, the researchers recruited 16 adults aged 70 or older. People with certain disorders and taking certain medications were excluded. The participants underwent a 10-hour overnight fast before being randomised into two groups, with one group receiving a low nitrate diet on the first two days and the other group receiving the high nitrate diet. On days four and five the diets were switched around, with a 24-hour ‘washout period’ and a further overnight fast between the two treatments.
Both diets included breakfast, lunch, dinner and snacks and had the same amount of calories and other nutrients. The low nitrate diet consisted mostly of grains, meats and dairy products and was low in fruits and vegetables. The high-nitrate diet, which contained 150 times more nitrates than the low nitrate diet, included 16 oz (454g) of beetroot juice at breakfast, as well as bananas and plenty of leafy green vegetables like spinach and lettuce.
The researchers took blood from the participants to measure nitrite levels before breakfast and one hour after finishing breakfast on the second day of each diet. Following the pos- breakfast blood sample, the participants’ brains were scanned using functional magnetic resonance imaging (an MRI) to measure the blood flow to different regions of their brain. All these times were based on the results of the preliminary study, which indicated the peak levels of nitrate and nitrites in the blood.
The participants ate breakfast in the laboratory but were given their lunches, dinners and snacks to eat at home and were asked to keep a diet record. They were asked to record any foods they did not consume that were part of the diet and anything they ate in addition to the foods provided.
The data was analysed using standard statistical methods.
What were the basic results?
The preliminary study found that the high nitrate diet was associated with substantially greater levels of both nitrates and nitrites, which increased through the three-hour testing period.
In the main study, 14 participants completed the four-day trial. Consumption of the high nitrate diet led to substantially greater plasma nitrate levels, compared to the low nitrate diet, and increases in blood levels of nitrite. The diets were generally well tolerated, although participants reported the common side effects of drinking beetroot juice of red stools and urine.
The researchers found that although the high nitrate diet did not alter the global blood flow to the brain, it led to an increased blood flow in the ‘frontal lobe white matter’. They say the high nitrate diet was associated with four areas of increased blood flow within the white matter of the frontal lobes. These areas are known to be at risk of chronic ischemia (insufficient blood supply) in elderly people.
How did the researchers interpret the results?
The researchers say their results suggest that dietary nitrate may be useful in improving regional blood flow to the brain in older adults, in ‘critical brain areas known to be involved in executive functioning’.
Conclusion
This preliminary study had several limitations:
* It was small, with only 16 adults involved in the main study, of which two did not finish the trial.
* The study was also short, over a period of just four days. As such, it is not certain how long these effects last for. The effects of a long-term high nitrate diet are also not known.
* As the participants ate their lunch and dinner at home it is possible that they did not stick to the diets they were given.
* The researchers only measured blood flow in parts of the brain and did not measure the participants’ cognitive abilities. As such, it is not known whether a high nitrate diet does benefit people in this way.
* It is uncertain if the high nitrate diet caused the increase in blood flow seen. Other unmeasured factors may have been involved.
In conclusion, this study does not provide robust evidence that a diet high in nitrates aids cognitive function. Further research is needed in larger numbers of people over a longer period. Plenty of vegetables may be good for your health as part of a balanced diet, but whether or not beetroot juice can have a beneficial effect on blood flow remains to be seen.