Blueberry Helps Older Brain Find Its Thrill

    In terms of U.S. fruit consumption, blueberries rank only second to strawberries in popularity of berries. Blueberries are not only popular, but also repeatedly ranked in the U.S. diet as having one of the highest antioxidant capacities among all fruits, vegetables, spices and seasonings. Antioxidants are essential to optimizing health by helping to combat the free radicals that can damage cellular structures as well as DNA.

    The antioxidant and anti-inflammatory properties of many dark-skinned fruits have long been touted as the panacea for a multitude of ailments. Due to their high flavonoid levels, blueberries—along with a number of other fruits—have colloquially been reclassified as a superfood. Now, investigators at the University of Exeter have just published some evidence that could lend some credence to blueberries’ promotional health claims. The researchers found that healthy people aged 65 to 77 who drank concentrated blueberry juice every day showed improvements in cognitive function, blood flow to the brain, and activation of the brain while carrying out cognitive tests.

    The findings from this new study were published recently in Applied Physiology, Nutrition, and Metabolism in an article entitled “Enhanced Task Related Brain Activation and Resting Perfusion in Healthy Older Adults after Chronic Blueberry Supplementation.”

    “Our cognitive function tends to decline as we get older, but previous research has shown that cognitive function is better preserved in healthy older adults with a diet rich in plant-based foods,” explained Joanna Bowtell, Ph.D., associate professor and head of sport and health sciences at the University of Exeter. “In this study, we have shown that with just 12 weeks of consuming 30 mL of concentrated blueberry juice every day, brain blood flow, brain activation, and some aspects of working memory were improved in this group of healthy older adults.”

    For the current study, the investigators recruited 26 healthy adults aged 65 or older, 12 of which were given concentrated blueberry juice—providing the equivalent of 230 grams of blueberries—once a day, while the remaining 14 participants received placebo supplementation. Before and after the 12-week period, participants took a range of cognitive tests while an MRI scanner monitored their brain function, and resting brain blood flow was measured.

    “Pre- and post-supplementation, participants undertook a battery of cognitive function tests and a numerical Stroop test within a 1.5T MRI scanner while functional magnetic resonance images (fMRI) were continuously acquired,” the authors wrote. “Quantitative resting brain perfusion was determined using an arterial spin labelling (ASL) technique, and blood biomarkers of inflammation and oxidative stress were measured. Significant increases in brain activity were observed in response to blueberry supplementation relative to the placebo group.”

    In comparison to the placebo group, those participants who took the blueberry supplement showed significant increases in brain activity in regions related to the tests (Brodmann areas, precuneus, anterior cingulate, and insula/thalamus). The study excluded anyone who said they consumed more than five portions of fruit and vegetables per day, and all participants were told to stick to their normal diet throughout.

    While the Exeter team was excited by their findings, they noted that continued research needs to be performed to understand the molecular mechanisms that underscore their observed results. Previous research has shown that risk of dementia is reduced by higher fruit and vegetable intake, and cognitive function is better preserved in healthy older adults with a diet rich in plant-based foods. Moreover, flavonoids, which are abundant in many plants, are likely to be an important component in causing these effects.