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Flavonoid-rich blueberries have a brain boosting role, say researchers

By Will Chu , 04-Apr-2017
Last updated on 04-Apr-2017 at 14:13 GMT2017-04-04T14:13:01Z

Higher flavonoid intake is associated with an attenuated rate of cognitive decline over a 10-year period in healthy adults. ©iStock
Higher flavonoid intake is associated with an attenuated rate of cognitive decline over a 10-year period in healthy adults. ©iStock

Regular consumption of concentrated blueberry juice may improve brain function in healthy older adults, British researchers have determined. 

Findings taken from a group of elderly adults who drank the juice every day indicated improvements in cognitive function and blood flow to the brain

Additional indications point to the activation of specific brain areas during cognitive tasks as well as a boost in working memory.

“Epidemiological studies demonstrate that risk of dementia is reduced by higher fruit and vegetable intake, and cognitive function is better in healthy older adults with a diet rich in plant-based foods,” said lead author Dr Joanna Bowtell, associate professor of Sport and Health Sciences at the University of Exeter.

“A group of polyphenols known as flavonoids, which are highly abundant in plants, are likely to be important bioactive components contributing to these favourable effects.”

While blueberries are a rich source of flavonoids, the nutrient’s brain enhancing effects have already been observed in other flavonoid-packed fruits and foods.  

Consumption of high flavanol cocoa improved cognitive function in healthy older adults after eight weeks in comparison to a low flavanol cocoa supplement.

Similarly, four weeks of supplementation with pomegranate, which are rich in the polyphenols from the elligitannins family, increased task-related brain activation and cognitive function in healthy older adults.

Most recently, eight weeks of consumption of flavanone-rich orange juice improved global cognitive function in healthy older participants in a crossover randomised crossover trial.

Nitric oxide efficacy

Four weeks of supplementation with pomegranate, which are rich in the polyphenols, increased task-related brain activation and cognitive function in healthy older adults. ©iStock

Participants made up of 26 adults in their late sixties, were randomised to drink either 30 ml blueberry concentrate or a placebo for 12 weeks.

The concentrate contained 30 ml of blueberry concentrate was consumed once per day and provided 387 mg anthocyanidins (34 mg malvidin, 108 mg cyanidin, 41 mg pelargonidin, 63 mg peonidin, 86 mg delphinidin, and 55 mg petunidin).

Just before and after consumption, the adults underwent a series of cognitive function tests as well as tests to highlight brain stimulation while performing simple tasks.

Blood flow to the brain was also assessed as was blood biomarkers of inflammation and oxidative stress.

Results indicated significant increases in brain activity were observed in response to blueberry supplementation relative to the placebo group within certain brain regions.

Supplementation with an anthocyanin rich blueberry concentrate improved brain perfusion and activation in brain areas associated with cognitive function in healthy older adults.

There was also evidence suggesting improvement in working memory after blueberry supplementation when compared to the placebo.

“The present study is the first to directly measure changes in cerebral perfusion in response to chronic fruit supplements, using arterial spin labelling,” the study commented.

“The mechanism of these effects is likely to be related to improved availability of the potent vasodilator, nitric oxide (NO), in the vasculature.”

Improved vascular function

Cell function has been has been shown to plays an important role in regulating cerebral blood flow through the release of vasoactive substances including NO.

The team thought it plausible that interventions which enhance vascular function could also improve cerebral perfusion and hence cognitive function.

In support of this hypothesis, one study found a meaningful link between neurovascular coupling and cognitive function in elderly participants with vascular risk factors. These factors showed enhancement after 30 days of high flavanol cocoa consumption.

“Blueberry concentrate consumed once per day for 12 weeks increased activation of brain areas associated with cognitive processes including memory and executive function, which tend to deteriorate with age,” the study concluded.

“These effects of blueberry appear to be mediated by improved vascular function as suggested by the improved resting perfusion of gray matter in the parietal and occipital lobes of the brain.”

Source: Applied Physiology, Nutrition, and Metabolism

Published online ahead of print: doi: 10.1139/apnm-2016-0550

“Enhanced task related brain activation and resting perfusion in healthy older adults after chronic blueberry supplementation.”

Authors: Joanna Bowtell et al.

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