Older women who regularly ate blueberries and strawberries had slower rates of cognitive decline than those who ate berries infrequently, a new study found. The findings, part of the large and ongoing Nurses’ Health Study, were published in the Annals of Neurology.
The study analyzed results from some 16,000 women who had completed extensive questionnaires about the foods they ate, beginning in middle age and then every four years thereafter. They also underwent tests of memory and thinking skills every two years, starting at age 70.
Over the next four years, the researchers found, those women who ate the most strawberries and blueberries had the lowest rates of memory decline. The greatest benefit occurred in women who ate at least one serving of blueberries or at least two servings of strawberries per week. Including berries in your regular diet, the researchers estimated, was associated with a delay in cognitive aging of up to two-and-a-half years.
"Among women who consumed two or more servings of strawberries and blueberries each week, we saw a modest reduction in memory decline,” said study author Dr. Elizabeth Devore, a researcher at Harvard Medical School. “This effect appears to be attainable with relatively simple dietary modifications."
Berries are rich in health-promoting flavonoids, the pigments that give them their color. Flavonoids are also found in other fruits and vegetables, as well as herbs, grains, legumes and nuts at well. In the study, total flavonoid intake was also associated with less decline in brain function.
The authors noted that there is "substantial biologic evidence" to support a diet rich in berries and other foods rich in flavonoids in protecting the brain. Several flavonoids have been to reduce levels of inflammation, which scientists increasingly link to Alzheimer’s and other forms of dementia. Flavonoids are also potent antioxidants, which prevent cell damage from the reactive forms of oxygen known as free radicals, and have been shown to have other protective effects on brain cells as well.
Dietary studies can be unreliable, experts caution, since people may not fill our food surveys accurately, and it can be difficult to tease out the cause-and-effect relationship between what we eat and the many factors that contribute to sound health. But "what makes our study unique is the amount of data we analyzed over such a long period of time,” said Dr. Devore. “No other berry study has been conducted on such a large scale."
Source: Elizabeth E. Devore ScD, Jae Hee Kang ScD, Monique M. B. Breteler MD, PhD, Francine Grodstein ScD: “Dietary intakes of berries and flavonoids in relation to cognitive decline.” Annals of Neurology online, 25 April, 2012.