Can beetroot boost your brain and body?
Recent research suggests that the naturally-occurring nitrate in vegetables such as beetroot and rocket can improve physical performance among athletes and may also improve mental acuity.
When we digest food or drink that is rich in nitrate, nitric oxide is produced, which is known to cause our blood vessels to widen. It is thought that this could lead to a range of health benefits.
(The benefits of nitrate in vegetables are in contrast to the effects of nitrates used in preservatives in processed meats, which have been linked to an increased risk of certain cancers.)
We wanted to test whether eating nitrate-rich vegetables could make a measurable improvement to the physical performance of ordinary, non-athletic individuals and whether these foods could also give a mental boost to the same group of people.
We teamed up with Prof Andrew Jones from the University of Exeter, to carry out an experimental first. We recruited 6 healthy middle-aged volunteers to test both the physical and mental effects of nitrate from vegetables.
We tested three parameters:
- Blood pressure.
- Oxygen uptake during physical exercise (which gives a measure of the effort required).
- Mental performance in a set of cognitive tests carried out both before and after the physical exercise task.
Our volunteers undertook all three of these tests before and after three different meals:
- A precisely-weighed salad containing spinach and rocket, which have naturally high levels of nitrate.
- A portion of beetroot juice, calculated to contain exactly the same quantity of nitrate.
- A control meal - a salad made from vegetables that naturally contain almost no nitrate.
The results for blood pressure showed that, after our volunteers consumed the high-nitrate salad, their blood pressure on average fell by around 3mm of mercury.
In addition, those who had the highest blood pressure before eating the salad benefitted the most.
The result was roughly the same for the beetroot juice, showing that it did not matter what form they took the nitrate in.
Sytolic blood pressure
For physical performance, the oxygen demand of exercise (high intensity cycling) was reduced by about 5%. This suggests that the effort required to exercise at that level of intensity is lower.
Our third test was designed to find out if nitrate improved our volunteers’ mental performance. Our results showed there was no change when our volunteers were at rest.
However, a difference emerged when they repeated the mental test after exercising. Whereas the control group’s cognitive function (‘mental sharpness’) became worse after exercise, for those who had eaten the high-nitrate salad, cognitive function was better preserved.
So when our volunteers were well rested, taking in nitrate didn’t make a difference. But after exercising, the nitrate helped to prevent their mental performance dropping off.
Cognitive function ('mental sharpness')
Our results showed some surprising benefits of eating high-nitrate vegetables.
The results for blood pressure have significant health implications. Extrapolating the benefit observed in our study group across the whole population of the UK could mean a reduction in adverse cardiovascular events, such as heart attacks and strokes, by around 10%.
For exercise, our results indicate that eating a high-nitrate vegetable meal before exercise reduces the effort required, so it might make people more inclined to exercise. It would suggest that the physical tasks of daily living, such as climbing stairs or walking to the local shops, would feel a little less tiring after eating a high-nitrate vegetable meal.
When it came to mental benefits, our results suggested that high-nitrate vegetables did not make any difference to mental performance in situations where people are at rest, but did appear to help maintain mental sharpness following exercise.
This is a fascinating result with some potential applications to everyday routines. For people who cycle or walk a substantial distance to work, consuming vegetables rich in nitrate beforehand could result in less ‘brain fade’ once at the office.
It is also surprising that these effects were observed after a single meal.
Taken together, these results suggest that eating high-nitrate vegetables can bring multiple and substantial benefits to health.