A new study published in Nutrients shows daily consumption of strawberries for 12 weeks reduced interference in memory and depressive symptoms among middle-aged, overweight adults with self-reported mild cognitive decline.
"Dementia is a general term that includes many different diseases, all without remedies," says Robert Krikorian, Ph.D., principal investigator and professor in the department of psychiatry at the University of Cincinnati Academic Health Center. "It is not clear when or if effective therapy will be available; prevention and mitigation through dietary and lifestyle choices is currently the best approach we have."
This double-blind, randomized controlled trial included five men and 25 women. One group received a strawberry powder prepared from whole fruit that had been desiccated, freeze-dried and milled. The second group received the control powder which was designed to have the same appearance, taste and carbohydrate load as the strawberry powder and contained fiber but no polyphenolic content. Daily servings of strawberry and control powder were sealed in packets for the convenience of the participants and to control daily dosage. Each packet of strawberry powder contained 13 grams, providing 36.8 milligrams anthocyanins derived from 130 grams whole fruit and equivalent to about 1 cup whole fresh strawberries. Participants were also asked to discontinue consumption of all berry fruits, juices and extracts for the duration of the study. This was done to mitigate the potential confound related to a group difference in consumption of berry products in the background diet.
"We wanted to work with a middle-aged, overweight population as dementia is a condition that is believed to develop over a period of decades. Furthermore, inflammation is likely a contributing factor related to metabolic disorders such as overweight/obesity, prediabetes and type 2 diabetes," explains Krikorian.
Specifically, the findings show that after the 12-week intervention, participants who were given the whole fruit strawberry powder made fewer 'intrusion errors' during a word list learning task (e.g., remembering/repeating words not included in the learning task). This has relevance in terms of identifying cognitive decline as memory interference is not uncommon in the context of aging, especially in late life dementia. Additionally, participants who were given the whole fruit strawberry powder reported lower levels of depressive symptoms which implies improved emotional coping capabilities. "Our findings can likely be attributed to the anti-inflammatory actions of the anthocyanins found in strawberries," added Krikorian.
In addition to providing polyphenols, strawberries are a source of many bioactive compounds. Strawberries provide100% of our daily vitamin C needs in single, 1-cup serving and contain heart-healthy nutrients like folate, potassium, fiber, phytosterols and polyphenols.
"We are excited with these findings and the future of polyphenol research," says Chris Christian, senior vice president at the California Strawberry Commission. "The link between strawberry consumption and brain health has been well explored in both clinical and population-based studies. For example, strawberries and pelargonidin, a biochemical primarily found in strawberries, were associated with a reduced risk of Alzheimer's dementia in studies conducted at Rush University. And, long-term observational studies, including the Health Professionals Study and the Nurses' Health Study, found that strawberry consumers had lower rates of cognitive decline," explains Christian.
