Consuming berries regularly may help curb cognitive decline among older adults, a new study finds. It suggests that eating one or more servings of blueberries or two or more servings of strawberries each week may help slow cognitive degeneration by several years.
"This is major step forward because little research previously has explored the effects of berries and flavonoids on memory in older adults," said Dr. Elizabeth Devore of Brigham and Women's Hospital and Harvard Medical School, which co-authored the study. "This is the first study of its kind -- the first large, epidemiologic study of berry intake in relation to memory decline."
Devore called the findings "exciting" because they suggest that "a simple dietary modification may provide memory benefits for older adults."
In the study, published Thursday in the Annals of Neurology, researchers used a sample of more than 16,000 women from the Nurses' Health Study, one of the longest ongoing studies looking at women's health in the U.S. The average age of the women sampled was 74.
After analyzing data on the participants' cognitive function, measured at two-year intervals, as well as their food consumption over the years, researchers concluded that women with highest intake of berries delayed their cognitive aging by as much as two-and-a-half years.
"If you can delay the onset by six months, let alone two or more years, the overall global impact on public health is immeasurable," said Dr. Richard Isaacson, an associate professor of neurology at the University of Miami School of Medicine. Cognitive decline develops over many years and could be a sign of future dementia and Alzheimer's -- a disease that the Alzheimer's Association says affects more than 5.4 million people in the U.S.
The authors of the new study state that flavonoids, a type of antioxidant, may be underlying the connection -- in particular, anthocyanidins, which are particularly prevalent in blueberries and strawberries. They cite prior research suggesting that those berry-derived flavonoids are uniquely capable of localizing in regions of the brain that control memory.
"But we also found that greater intakes of total flavonoids were associated with slower decline in memory," Devore said. "So it appears that consuming a wider range of flavonoid-rich foods (e.g., tea, apples, oranges) might be helpful for memory as well."
Of course, the new study is not without limitations. Because it was observational, researchers were unable to rule out the possibility that other lifestyle characteristics, such as physical activity and income, might have influenced rates of memory decline. Devore said that additional studies are now needed to confirm the results in other populations.
The research is not the first to link cognitive degeneration and nutrition. In recent years, numerous studies have questioned the role of diet in cognitive decline, with researchers focusing on the role that the Mediterranean diet may play in reducing the risk of mild cognitive impairment. Another recent study found that adults who eat up to 6,000 calories per day may have double the risk of developing mild cognitive impairment, a type of memory loss.
For now, it is impossible to know exactly how long one needs to consume a flavonoid-rich diet in order to see the potential cognitive benefits, but experts say they are heartened by the possible positive effects of eating such foods.
"We don't have enough data to answer that question," said Isaacson. "But people can begin to change what they eat tomorrow and have an incremental change on their brain."