Twelve weeks of supplementation with 26 grams of freeze-dried wild blueberry powder (WBB), which provided 302 mg of anthocyanins, were associated with significant improvements in flow-mediated dilation (FMD), a measure of endothelial function. Improvements in systolic blood pressure were also reported.
Data published in the American Journal of Clinical Nutrition also indicated that a number of cognitive health measures were enhanced, including immediate recall and task accuracy.
“To our knowledge, this is the first study to investigate the impact of blueberry consumption on cognitive and cardiovascular function simultaneously in a group of healthy older adults,” wrote scientists.
“Long-term consumption of a dietary achievable amount of WBB was observed to enhance vascular and cognitive function in older adults and may be a plausible and cost-effective dietary-based strategy to tackle the burden of age-related cognitive decline and vascular dysfunction,” they added.
Studies in older adults have also found potential cognitive benefits of flavonoid-rich blueberry consumption. For example, a 2017 paper published in Applied Physiology, Nutrition, and Metabolism reported that 30 ml of blueberry concentrate per day (providing 387 mg anthocyanidins) for 12 weeks was associated with “significant increases in brain activity […] in response to blueberry supplementation relative to the placebo”. The researchers also report improved working memory in their subjects (adults approximately 68 years of age).
In addition, a 2010 study led by Robert Krikorian from the University of Cincinnati Academic Health Center found that a daily drink of about 500 mL of blueberry juice was associated with improved learning and word list recall, as well as a suggestion of reduced depressive symptoms in older people with early memory problems (Journal of Agricultural and Food Chemistry, Vol. 58, No. 7, pp 3996–4000).
The London-based scientists recruited 61 healthy older adults to participate in their double-blind, parallel randomized controlled trial. The volunteers were randomly assigned to receive either 26 grams of WBB powder or placebo for 12 weeks. The dose was equivalent to 178 grams of fresh blueberries.
The results showed that FMD increased by 0.85%, while ambulatory systolic BP decreased by 3.59 mmHg.
“The improvements seen here in vascular function have clinical significance, as according to recent meta-analyses, an 0.85% increase in FMD translates to a 8.5-11% decreased risk of developing CVD, while a decrease in BP of 3.6 mmHg would translate into a 7% lower risk of CVD events,” explained the researchers.
Improvements in episodic memory and executive function were also reported by the researchers. In particular, better immediate recall of a word list and improvement in switching accuracy, were identified as being significantly increased.
“The relatively modest improvements in episodic memory and executive function seen in our study highlights the need for further substantiation of these effects before firm conclusion on risk reduction from flavonoid-rich interventions could be drawn,” they said.
On the other hand, blueberry supplementation did not significantly change cerebral blood flow or the composition of the gut microbiota.
However, blueberry powder consumption was associated with significant increases in the alpha diversity from baseline, and increases in levels of beneficial bacteria such as Ruminiclostridium and Christensellenacea.
“This suggests that WBB (poly)phenols may reduce future cardiovascular disease (CVD) disease risk in an older population, and may improve episodic memory processes and executive functioning in older adults at risk of cognitive decline,” wrote the scientists.
“Further large-scale studies are needed to confirm the findings of this small-scale investigation, and to explore the exact mechanisms of action.”
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.1016/j.ajcnut.2023.03.017
“Wild Blueberry (Poly)phenols can Improve Vascular Function And Cognitive Performance In Healthy Older Males And Females: A Double-Blind Randomized Controlled Trial”
Authors: E. Wood et al.
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