Drink 2-3 glasses of blueberry juice every day for 12 weeks and you'll notice a marked improvement in your memory. Researchers at the University of Cincinnati base their claim on experiments they did with sixteen healthy people in their seventies and eighties who were experiencing sporadic memory failure.
Animal studies have already shown that the phenols in the American blueberry [Vaccinium angustifolium] – a close relative of the European blueberry [Vaccinium corymbosum] – improve the functioning of aging brains: they inhibit the aging process. That's why the researchers, funded by the Wild Blueberry Association of North America, investigated whether drinking a couple of glasses of blueberry juice every day helped elderly people to become less forgetful.
The researchers recruited sixteen elderly people through ads in local newspapers. Nine of the subjects drank 2-3 glasses of blueberry juice daily. The other seven drank soft drinks that did not contain phenols. After 12 weeks the researchers got the subjects to perform two tests to evaluate how well their memory was functioning.
In the California Verbal Learning Test [CVLT] the researchers looked at how many words the subjects could remember. The Verbal Paired Associate Learning Test [V-PAL] is a little more complicated. In this test the subjects had to remember newly formed words, which is only possible if the brain is capable of making new connections.
The figure below shows the test scores of the subjects after 12 weeks of drinking juice or a placebo. The subjects in the berry juice group did significantly better.
Berries contain phenol compounds composed of gallic acid units and compounds based on cyanidin-3-glucoside [structural formula shown here]. Thanks to BioTest the latter compound has become pretty hip in the sports supplement world. It improves the glucose uptake of muscle tissue. The effects measured may be partly due to increased insulin sensitivity, but it's also possible that the phenols in berries improve memory functioning of brain cells directly.
The researchers stress that their study population was miniscule. "Replication of the findings in a larger, controlled trial will be important to corroborate and amplify these data", they write.