A large new study has shown that eating berries at least once a week may protect the brain from age-related memory loss.
The study of more than 16,000 women taking part in the Nurses' Health Study involved following them up since 1980. Between 1995 and 2001, researchers also measured the mental function of women who were over 70 and had not had a stroke.
Mental functioning was measured during three telephone interviews that were spaced about two years apart. In the interviews, researchers asked the women to recall details from a paragraph they'd just heard, for example, or to remember the order of words or numbers in a list.
Results showed that when women who ate the most blueberries and strawberries were compared who ate the fewest they found that those who ate the most had a slower rate of developing memory problems. The difference was equal to about two-and-a-half years of aging. On average, the berry eaters were eating a single half-cup serving of blueberries or two half-cup servings of strawberries each week.
“This is pretty compelling evidence to suggest that berries do appear to have memory benefits,” said researcher Elizabeth E. Devore, instructor in medicine at Brigham and Women's Hospital in Boston. “These are simple interventions that appear to have pretty healthful effects,” Devore said.
However, women in the study who ate berries regularly also got more exercise and had higher incomes - two factors that are also linked to having better health. But researchers say that even after they adjusted their results to account for differences like that, having a diet high in fruits and vegetables, particularly berries, still appeared to be linked to having a sharper memory.
The study, which is published in the Annals of Neurology, builds on smaller studies in mice and humans that have suggested that berries may benefit the brain.
Berries, particularly blueberries, are rich in a particular kind of antioxidant compound called anthocyanidins. Anthocyanidins have the ability to move from the blood into the brain. And studies in animals have shown that these compounds concentrate in brain centers responsible for memory and learning.
“I think it's very exciting,” said Brent Small, professor of aging studies at the University of South Florida in Tampa. “Because there's not a lot that's been reported in the human literature that's focused on these types of compounds.” Small was not involved in the new study. “The fact that they were able to see an effect for people who are generally healthy and who aren't experiencing significant drops in performance is interesting,” Small said.
Experts agree that more studies need to be conducted to prove the berries alone are behind the benefit. But they say there's no real harm in adding more berries to your diet, even before all the evidence is in.
“We know that flavonoids in fruits and vegetables act as really good protection for a range of chronic diseases,” including cancer and diabetes, said Nancy Copperman, director of public health initiatives at the North Shore-LIJ Health System in Great Neck, N.Y. “And now, with this study, they've actually looked at how these flavonoids, especially the types of flavonoids found in blueberries and strawberries, really might protect cognitive function in women,” she said.
The number of Australians aged 65 and older grew 26 per cent from 2000 to 2010, according to the Australian Bureau of Statistics. Robert Graham, an internist at New York's Lenox Hill Hospital who was not involved with the study, says eating more berries is a good idea for people of any age. “Large epidemiological studies, such as this one, add to the basic science research that the antioxidant and anti-inflammatory properties of berries have a beneficial role in age-related cognitive decline,” said Graham. “I would advise all my patients, at any age, to eat more berries. Berries are an easy, nutritious and delicious way to preserve brain function.”
Associate Professor Shawn Somerset of the Australian Catholic University in Brisbane said rather than focus on berries, people should consume a wide range of fruits and vegetables known to contain flavonoids. “Australian intake of vegetables is inferior to fruit, therefore vegetable consumption needs to be promoted above fruit consumption,” said Somerset. “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. This translates to consuming a range of vegetables and fruits, not just one type.”