The study comprised 26 participants, aged 55 years and older, who had high blood pressure. None of the participants engaged in regular exercise, and they were taking up to two medications to help lower their blood pressure.
All subjects were required to engage in 50 minutes of moderately intense exercise on a treadmill three times per week for 6 weeks. One hour before each session, half of the participants consumed a beetroot juice supplement containing 560 milligrams of nitrate, while the remaining participants consumed a placebo low in nitrates.
At the end of the 6 weeks, the researchers measured participants’ brain functioning using MRI.
The team found that subjects who consumed the beetroot juice supplement prior to exercising demonstrated a structurally stronger somatomotor cortex (showed in image is greater activation (red colours) in BRJ group)- a brain region that helps to control body movement – compared with participants who consumed the placebo.
Furthermore, subjects who drank the beetroot juice supplement also showed greater connectivity between the somatomotor cortex and the insular cortex, a brain region associated with motor control, cognitive functioning, emotion, and other brain functions. Such connectivity is usually seen in the brains of younger individuals, the team notes.
They suggest that beetroot juice strengthens the somatomotor cortex further through its nitrate content; its conversion into nitric oxide boosts the delivery of oxygen to the brain.
“Nitric oxide is a really powerful molecule. It goes to the areas of the body which are hypoxic, or needing oxygen, and the brain is a heavy feeder of oxygen in your body,” says Rejeski.
Presley and colleagues measured cerebral perfusion using MRI after administering a high- versus low-nitrate diet for 24 h to a group of elderly humans (74.7 ± 6.9 years). The test diet included beetroot juice and provided 773 mg of nitrate compared to 5.5 mg for the low-nitrate diet. The authors demonstrated that the diet high in dietary nitrate did not significantly increase global CBF, but regional cerebral perfusion improved in frontal lobe white matter, especially between the dorsolateral prefrontal cortex and the anterior cingulate cortex, which are known to be involved in executive functioning.
However, whether the observed increase in regional CBF in coincides with concurrent improvements in cognitive functioning remains to be elucidated. That being said, an improvement in blood flow is promising considering a reduction is associated with dementia, poor aging, and other circumstances including concussion.
In another study, Following a 90 minute drink/absorption period, participants performed a selection of cognitive tasks that activate the frontal cortex for 54 min. Near-Infrared Spectroscopy (NIRS) was used to monitor CBF and hemodynamics, as indexed by concentration changes in oxygenated and deoxygenated-haemoglobin, in the frontal cortex throughout. The bioconversion of nitrate to nitrite was confirmed in plasma by ozone-based chemi-luminescence. Dietary nitrate modulated the hemodynamic response to task performance, with an initial increase in CBF at the start of the task period, followed by consistent reductions during the least demanding of the three tasks utilised. Cognitive performance was improved on the serial 3s subtraction task. These results show that single doses of dietary nitrate can modulate the CBF response to task performance and potentially improve cognitive performance, and suggest one possible mechanism by which vegetable consumption may have beneficial effects on brain function.
Wondering how you can reap the benefits of beet root juice? Check out the first post on BRJ here, which provides a simple step by step guide.