The study found that supplemental blueberries for only 12 weeks boosted memory in older people with early memory problems. Researchers tested the effect of blueberry juice on memory in a group of volunteers in their 70s with early memory decline. In the study, the study group drank 2 to 2.5 cups of blueberry juice while the control group drank a beverage every day for two months.

Those who drank blueberry juice experienced significant improvements in learning and word recall lists, as well as a suggestion of reduced depressive symptoms and lower glucose levels.

"These preliminary memory findings are encouraging and suggest that consistent supplementation with blueberries may offer an approach to forestall or mitigate neurodegeneration," the authors wrote in the report.

"Replication of the findings in a larger, controlled trial will be important to corroborate and amplify these data," wrote the researchers.

"On balance, this initial study establishes a basis for further human research of blueberry supplementation as a preventive intervention with respect to cognitive aging," they concluded.

Previous studies have linked blueberry consumption to reduced risk of Alzheimer's, and animal studies have suggested that eating blueberries may boost memory in older people, however this is the first study carried out in humans.

The beneficial effects of the blueberries are thought to be linked to their flavonoid content - in particular anthocyanins and flavanols. These are responsible for the blueberry's rich, dark color, and have also been found to help ward off a range of ailments including heart disease, cancer, Alzheimer's disease and diabetes. It is believed these substances may exert their effects on learning and memory by enhancing existing neuronal connections, making it easier for messages to pass from brain cell to brain cell and protect the cells from death, or neurodegeneration.

Research paper details:

R. Krikorian, M.D. Shidler, T.A. Nash, et al. Blueberry Supplementation Improves memory in Older Adults. Journal of Agricultural and Food Chemistry, 2010, published online ahead of print.