Blueberries and other phytochemical-rich foods could help in increasing memory capacity by reversing age-related deficits in memory, according to a study published in the journal Free Radical Biology and Medicine.

After supplementing the diet of rats with blueberries over a 12-week period, the research team from the University of Reading and the Peninsula Medical School in the United Kingdom said that improvements in spatial working memory tasks emerged within three weeks and continued throughout the period of the study.

Three groups of adult male rats were used in the study. The first group comprised of “young” rats, aged six months at the start of the testing period, while the remaining rats were all 18 months old and were randomly assigned to either an “aged” group or an “aged, plus blueberry-supplemented” group. Those in the blueberry-supplemented group had powdered blueberries incorporated into the standard rat feed at a level of two percent.

The researchers said that the two intervention diets used contained a defined and characterized amount of flavonoids (anthocyanins and flavonols) and were as far as possible macro- and micronutrient-matched. The two diets were isocaloric and matched for major antioxidant vitamins via the addition of corn starch and vitamin C to the control diet. The mean intake of flavonoids by blueberry-fed animals was approximately 10.5 mg per day (anthocyanins: 6.68 mg/day; flavonols: 3.85 mg/day).

Rats were tested in cross-maze apparatus, which they had to navigate in order to receive reward pellets. The animals were given a week’s training in the apparatus before supplementation began in order to ensure that they ran reliably.

The researchers set up an alternate navigation/reward system, which involved rats having to make a choice as to which path to take in order to receive the pellets. For each trial, accuracy and time taken to make a choice were measured.

Animals in the “young” group were found to perform “extremely well and very consistently,” scoring an average of 90% correct on each test day. The “aged” animals were substantially impaired on this task compared to the young animals, with an average score of only 57% correct. Similarly, the “aged, plus blueberry-supplemented” group showed an age-related deficit in performance compared to the “young” animals at baseline, achieving only 60% accuracy of choice.

Three weeks of blueberry supplementation produced a significant increase in performance in these animals, with accuracy rising to 83% by testing in week three. This increase in performance accuracy was maintained throughout the remainder of the treatment period, said the researchers.

“This study not only adds to the claim that eating blueberries is good for you, it also provides support to a diet-based approach that could potentially be used to increase memory capacity and performance in the future,” said researcher Dr. Matt Witterman, from the Institute of Biomedical and Clinical Science, Peninsula Medical School.

Free Radical Biology and Medicine 45(3):295-305, 2008

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