Eating berries often may help slow age-related memory loss, a new U.S. study suggests.
Women with the highest intake of blueberries or strawberries showed about 1.5 to 2.5 years of delays in cognitive aging such as thinking, remembering and reasoning abilities.
For the study in Thursday's online issue of the Annals of Neurology, researchers measured the cognitive function of 16,010 women in telephone interviews about every two years for six years.
"We provide the first epidemiologic evidence that berries may slow progression of cognitive decline in elderly women," said study author Dr. Elizabeth Devore with Brigham and Women's Hospital and Harvard Medical School in Boston.
The participants in the Nurses Health Study were tested on their recall of the order of words or numbers in a list or highlights of a paragraph that was just read to them. They also filled in detailed diet questionnaires from 1976 to 2001.
The woman who ate the most berries were eating a half cup of blueberries or two half-cup servings of strawberries a week.
Those in the highest berry consumption also tended to have higher levels of physical activity and income compared with those who ate the fewest berries. Factors such as education and smoking were also taken into account in the analysis.
"These findings potentially have substantial public health implications, as increasing berry intake represents a fairly simple dietary modification to test in older adults for maintaining cognition," the study's authors concluded.
Experimental data in small numbers of older people and in animal models also point to cognitive benefits of berries, the researchers said.
Flavanoids in plants have antioxidant and anti-inflammatory properties. Berries contain flavanoids called anthocyanidins that cross from the blood into the brain's hippocampus, which is involved in learning and memory.
Flavanoids from other food and drinks such as citrus fruits, tea, red wine and onions were considered but the participants didn't eat enough other berries, cherries or grapes to detect the effects of those fruits.
To save money, people may buy frozen berries, or freeze fresh berries themselves.
Instead of focusing on berries, people should consume a wide range of fruits and vegetables known to contain flavonoids, advised Prof. Shawn Somerset of the Australian Catholic University in Brisbane.
"The most sensible advice is to consume a wide range of flavonoids, rather than large amounts of specific ones, since excessive amounts of some are problematic," Somerset told the Australian Broadcasting Corporation. "This translates to consuming a range of vegetables and fruits, not just one type."
The researchers acknowledged limitations of the study, such as the self-reported dietary information. The results may not apply to men although few studies have found substantial sex differences in dietary risk factors for cognitive decline and dementia, they said.
The study was funded by the U.S. National Institutes of Health National Cancer Institute and the California Strawberry Commission.