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.