People who consumed a daily dose of blueberries experienced better cognitive performance and better cardiovascular health, according to a new study published in the American Journal of Clinical Nutrition.
Previous research has shown that eating blueberries (and certain other berries) may provide a range of health benefits — including improved blood glucose control in people with type 2 diabetes, a lower risk of developing dementia, and better heart health. At least some of these health benefits may be due to beneficial chemicals found in blueberries known as polyphenols, which are also found in a wide range of other plant foods. Blueberries, in particular, contain a type of polyphenol known as anthocyanins, which can be measured to provide a standardized dose in products like freeze-dried blueberries.
To get cutting-edge diabetes news, strategies for blood glucose management, nutrition tips, healthy recipes, and more delivered straight to your inbox, sign up for our free newsletters!
For the latest study, 61 healthy older adults (ages 65 to 80) were randomly assigned to consume a daily dose of one of two different powders — either 26 grams of freeze-dried wild blueberries, or a placebo (inactive) powder that tasted the same but didn’t contain any actual blueberries. The real blueberry powder contained 302 milligrams of beneficial anthocyanins, while the placebo powder did not contain any anthocyanins. Participants underwent a range of measurements at the beginning of the study and after consuming their daily powder for 12 weeks — including flow-mediated dilation (a measure of blood vessel function), blood pressure, and tests looking at arterial stiffness, cerebral (brain) blood flow, and cognitive function.
Blueberries linked to improved cognitive and cardiac measures
The researchers found that after 12 weeks, the blueberry group experienced a significant average increase in flow-mediated dilation — 0.86% more than the placebo group. The blueberry group also saw their 24-hour average systolic blood pressure (the “top number” measured during heartbeats), as measured by a continuously worn monitor, drop by an average of 3.59 mmHg compared with the placebo group. When it came to cognitive performance, the blueberry group experienced improvement in being able to immediately recall words or phrases in an “auditory verbal learning task,” along with better accuracy in what’s known as a “task-switch task” (switching from one task to another) — improvements that were not seen, overall, in the placebo group.
Not surprisingly, the amount of polyphenols in participants’ urine increased significantly in the blueberry group compared with the placebo group over the 12 weeks. No overall changes in cerebral blood flow or the composition of gut bacteria were seen in either group.
These results suggest, the researchers wrote, that the polyphenols in blueberries “may improve episodic memory processes and executive functioning in older adults at risk for cognitive decline.” The amount of freeze-dried blueberry powder that participants consumed daily is equivalent to about 178 grams of fresh (or frozen) wild blueberries — possibly a useful target if you’re looking to reap the potential health benefits of eating blueberries daily.
Want to learn more about maintaining cognitive health with diabetes? Read “Nine Tips to Keep Your Memory With Diabetes,” “Staying Sharp: Seven Ways to Keep Your Brain Healthy With Diabetes,” “Keeping Your Brain Strong With Diabetes” and “Memory Fitness: How to Get It, How to Keep It.”