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Daily blueberries can improve cognition and fasting insulin

In this randomized controlled trial, daily blueberries improved the memory, executive ability, and fasting insulin of middle-aged adults with overweight, insulin resistance, and an elevated risk of future dementia.


Dementia currently has no treatment, so prevention of cognitive decline is key. Beginning in midlife, lifestyle changes may target modifiable risk factors (e.g., poor nutrition) to possibly reduce neurodegenerative changes in late-life.

Blueberries contain anthocyanins and proanthocyanidins (bioactive flavonoids), among other nutritional components that may have health benefits. Can daily blueberry intake improve cognitive performance in middle-aged adults with greater risk for age-related cognitive decline and dementia?

The study

This randomized controlled trial evaluated the effect of eating blueberries on cognitive health in 33 middle-aged adult participants with overweight and subjective cognitive decline (i.e., at risk of future dementia). The blueberries were consumed in the form of freeze-dried powder in an amount equal to 0.5 cups of the whole fruit and were compared to a placebo powder that was matched for sugars, glycemic load, appearance, and taste but did not contain fiber. The powders were consumed daily for 12 weeks.

Cognitive health domains (i.e., executive ability, learning/memory, mood) were assessed using five different neurocognitive measures (i.e., validated tests or questionnaires) at the beginning and end of the trial.

Metabolic markers (blood lipids, glucose, and insulin), anthropometric measurements (body weight, BMI, waist circumference), mitochondrial oxygen-consumption rate, and dietary intakes were also assessed.

The results

Daily blueberry powder improved selected aspects of cognitive performance (i.e., executive abilities and memory related outcomes) and fasting insulin but did not affect blood lipids, anthropometric measures, or other measured metabolic parameters.

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