Insights & Discussion
Blueberry consumption significantly improves two-back test accuracy, suggesting potential cognitive benefits.
Methodology: A comprehensive search was conducted in April 2021 for relevant clinical trials on blueberry supplementation and its effects on cognitive performance and mood. The search was conducted through PubMed/Medline, Scopus, Embase, and Google Scholar, and the random effect size was used to estimate the pooled effect size. Cochrane Q test and I-squared tests were used to evaluate heterogeneity between studies, and a subgroup analysis was done to detect potential sources of such heterogeneity. Fourteen randomized trials were included in the quantitative analysis, and six were pooled for statistical analysis.
Results: Blueberry intervention did not produce any significant impact on mood state score, attention task reaction time, or on the percentages of attention task accuracy. Similarly, it had no significant effect on one-back test accuracy. However, a noticeable positive effect was detected in two-back test accuracy, indicating possible cognitive benefits associated with blueberry consumption.
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Consumption of blueberry powder daily improves vascular function, cognitive abilities, and reduces blood pressure in healthy older individuals.
2023 The American Journal of Clinical Nutrition Wild blueberry (poly)phenols can improve vascular function and cognitive performance in healthy older individuals: a double-blind randomized controlled trial Wood E, Hein S, Mesnage R, Fernandes F, Abhayaratne N, Xu Y, et al.
Randomised Controlled Trial Blueberry Cardiovascular Disease Cognitive Function
This double-blind, parallel randomized controlled trial engaged 61 healthy older individuals aged between 65 to 80 years old. Participants were given either 26g of freeze-dried wild blueberry (WBB) powder, comprising 302 mg anthocyanins, or a similar placebo with zero mg anthocyanins. Measurements were made for endothelial function, cognitive function, arterial stiffness, blood pressure, cerebral blood flow, gut microbiome, and blood parameters, both at the start of the trial and again following 12 weeks of daily consumption. In addition, plasma and urinary polyphenol metabolites were analyzed through the use of microelution solid-phase extraction combined with liquid chromatography-mass spectrometry.
In the WBB group, there was a notable increase in endothelial function and a decrease in 24-hour ambulatory systolic blood pressure, when compared to the placebo group. Enhanced immediate recall on the auditory verbal learning task was also observed, along with better accuracy on a task-switch task following administering of WBB. Notably, the total 24-hour urinary excretion of polyphenols also significantly increased in the WBB group comparative to the control group. In contrast, there were no discernible changes in cerebral blood flow or gut microbiota composition. These findings imply that WBB polyphenols could contribute to reducing future cardiovascular disease risk in older populations, and might enhance memory processes and executive functioning in older adults at risk of cognitive decline.
Consumption of wild blueberries over six months can improve cognitive performance and speed of processing information amongst older adults.
2022 Nutritional Neuroscience Six-month intervention with wild blueberries improved speed of processing in mild cognitive decline: a double-blind, placebo-controlled, randomized clinical trial. Cheatham CL, Canipe LG, Millsap G, Stegall JM, Chai SC, Sheppard KW, et al.
Randomised Controlled Trial Blueberry Cognitive Function
The methodology of this research involved conducting a double-blind, randomized placebo-controlled trial where participants with cognitive issues ascertained by Montreal Cognitive Assessment scores were asked to consume wild blueberry or placebo powder daily for a 6-month period. There was also a separate reference group involved, comprised of individuals devoid of any cognitive issues. These individuals were tested at the commencement and end of the trial using the Cambridge Neurological Test Automated Battery and an electrophysiological paradigm named event-related potentials.
The results presented disclosed a significant improvement in the speed of processing information in the group consuming blueberries compared to the placebo group over the 6-month intervention period. Additionally, the speed of this group's processing was re-established to the level of the reference group, revealing the restoration of cognitive abilities. The most distinct enhancement was noted in participants aged between 75-80 years in the blueberry group.
Blueberries and their products may improve certain measures of cognitive performance, particularly memory, and positively affect mood.
2020 Brain, Behavior, and Immunity The effect of blueberry interventions on cognitive performance and mood: A systematic review of randomized controlled trials Travica N, D'Cunha NM, Naumovski N, Kent K, Mellor DD, Firth J, et al.
Systematic Review Blueberry Cognitive Function Memory
The systematic review process involved evaluating the results from randomized controlled trials that investigated the effects of blueberries and blueberry products on cognitive performance and mood. A total of eleven articles, encompassing twelve studies, were examined. The studies employed various forms of blueberries - freeze-dried, whole, and concentrate. Different demographic groups were considered across the studies: children, young adults, and older people with or without known cognitive impairment. The studies considered the impact of consumed or supplemented blueberries, varied in dosage and duration, on cognitive performance, specifically in relation to both short-term and long-term memory, as well as spatial memory. Also, the studies investigated the effects on mood, particularly the potential enhancement of positive feelings.
The findings revealed that eight out of twelve studies reported an improvement in cognitive performance following the ingestion of blueberries, although variations in each specific study's design, dosage, and anthocyanin content made cross-study comparisons challenging. Regarding mood, out of five studies, only one study reported a significant improvement in mood upon consumption of blueberry products, while the others reported no significant change. Despite differences, all studies featured a low risk of bias overall, underscoring the perceived validity of these findings.