“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 Robert Krikorian, PhD., professor emeritus in the UC College of Medicine’s Department of Psychiatry and Behavioral Neuroscience. “There is epidemiological data suggesting that people who consume strawberries or blueberries regularly have a slower rate of cognitive decline with aging.”
Strawberries also contain other micronutrients called ellagitannins and ellagic acid to go along with the anthocyanins that are also associated with health benefits, which could be helpful to the approximately 50% of individuals who develop insulin resistance (prediabetes) at around middle age, which is a known factor for many chronic diseases. While strawberry consumption has been studied for metabolic and cardiovascular benefits there are relatively few on the cognitive effects.
“This study assessed whether strawberry consumption might improve cognitive performance and metabolic health in this population and, if so, whether there might be an association between cognitive enhancement and reduced metabolic disturbance,” said Krikorian.
This study involved 30 overweight participants between the ages of 50-65 years old with mild cognitive decline. Over a period of 12 weeks, the participants abstained from berry consumption of any kind with the exception of a daily packet containing a supplement powder to be mixed with water for breakfast every day. Half of the participants were given a placebo powder packet, and the other half were given a powder packet containing the equivalent of one cup of whole strawberries.
Over the study period, the participants were given tests to measure cognitive abilities, and their mood, metabolic data, and intensity of depressive symptoms were tracked. According to the researchers, those in the strawberry group demonstrated decreases in their memory interference, which is consistent with an overall improvement in their executive abilities.
“Reduced memory interference refers to less confusion of semantically related terms on a word-list learning test,” Krikorian said. “This phenomenon generally is thought to reflect better executive control in terms of resisting intrusion of non-target words during the memory testing.”
Additionally, those in the strawberry group also experienced significant reductions in their depressive symptoms, which Krikorian explains could be a result of “enhanced executive ability that would provide better emotional control and coping and perhaps better problem-solving.”
“Executive abilities begin to decline in midlife and excess abdominal fat, as in insulin resistance and obesity, will tend to increase inflammation, including in the brain,” he said. “So, one might consider that our middle-aged, overweight, prediabetic sample had higher levels of inflammation that contributed to at least mild impairment of executive abilities. Accordingly, the beneficial effects we observed might be related to moderation of inflammation in the strawberry group.”
This study found no effect on the participants’ metabolic health. While more studies are required to determine the exact underlying pathways, the researchers believe that the strawberry treatment may have led to improvements by reducing inflammation in the brain. Moving forward, the researchers suggest that future trials should include a larger population and differing doses of supplementation.
