Strawberries may stave off dementia

Strawberries can potentially contribute to the prevention of dementia, with a small study suggesting that supplementation with whole-fruit strawberry powder helps improve memory in middle-aged adults.

Twelve-week data from 30 participants showed that those who received the strawberry supplement had fewer intrusion errors on a word list learning task compared with those who received placebo (p=0.02). This, according to the investigators, represented a decrease in the interference of extraneous information during learning and recall. [Nutrients 2023;doi:10.3390/nu15204431]

“Such interference typically involves an inability to inhibit intrusion of competing exemplars within a semantic category. The finding of improvement in this regard for the strawberry-treated group might be understood as reflecting more effective executive control processes supporting suppression of nontarget terms,” the investigators explained. [Mem Cogn 2011;39:806-817; Mem Cogn 2014;42:950-964]

“Memory interference is not uncommon in the context of ageing and, especially in late life dementia, has been associated with greater regional neurodegeneration,” they added. [Mem Cogn 2014;42:950-964; J Alzheimers Dis 2017;56:1119-1126]

Less depressed

Of the patients included in the study, 15 (mean age 55.9 years, mean body mass index [BMI] 35.1 kg/m²) were assigned to the group that received whole-fruit strawberry powder and the other 15 (mean age 57.0 years, mean BMI 37.2 kg/m²) were assigned to the group that received placebo. The intervention was administered daily and lasted 12 weeks.

Other than memory improvement, the strawberry group also showed lower levels of depressive symptoms compared with the placebo group (p=0.04).

“This relative mood enhancement experienced by the strawberry-treated group implies improved emotional coping capability and lower levels of stress,” the investigators pointed out.

“Such coping enhancement also can be understood as implying improved executive ability; that is, better ability to manage everyday activities and social relationships and improved response control and greater flexibility,” they said. [J Clin Med 2021;10:3122; Anxiety Stress Coping 2014;28:31-49]

Finally, the strawberry powder intervention had no effect on metabolic parameters including fasting glucose (p=0.61), fasting insulin, (p=0.29), HOMA2-IR (p=0.45), glycated haemoglobin (p=0.67), or the TG/HDL ratio (p=0.85). Likewise, anthropometric measures such as body weight (p=0.17) and waist circumference (p=0.34) did not change substantially with the strawberry powder vs placebo.

According to the investigators, the observed lack of effect of the intervention on metabolic measures could have been influenced by the small sample size, length of the intervention, or comparatively low anthocyanin dose.

“Both strawberries and blueberries contain antioxidants called anthocyanins, which have been implicated in a variety of berry health benefits such as metabolic and cognitive enhancements,” said lead study investigator Prof Robert Krikorian of University of Cincinnati Academic Health Center, Cincinnati, Ohio, US.

“There is epidemiological data suggesting that people who consume strawberries or blueberries regularly have a slower rate of cognitive decline with ageing,” he added.

Krikorian called for additional studies with larger samples, longer intervention periods, and differing dosing regimens to establish the benefits of strawberry intake with respect to cognition and metabolic function in the context of ageing.