Findings affirm prior indications that antioxidants in berries may help deter memory loss
by Craig Weatherby
Berries and antioxidant-rich berry extracts have shown the ability to enhance brain function in a variety of ways.
We reported on one revealing animal study last July… see “Blueberries May Reduce Alzheimer’s Risk and Damage,” which contains links to several other berry-brain stories.
Now, the results of a second such study reinforce the evidence indicating that blueberries—and other berries and fruits abundant in particular antioxidants—could help sustain people’s youthful capacity for memory and learning into middle age and beyond.
In brief, British scientists supplemented the diet of older rats with blueberries, and witnessed dramatic improvements in the rodents’ learning and “spatial memory” within three weeks.
How the berry study worked… and what it showed
Scientists at Britain’s University of Reading and Peninsula Medical School used three groups of adult male rats for the study:
- Young rats (6 months old) fed standard chow.
- Aged rats (18 months old) fed standard chow.
- Aged rats (18 months old) fed standard chow, with powdered blueberries replacing two percent of it.
The diets were identical, except for the blueberry powder, which provided 10.5 mg of flavonoids per day, consisting of 6.68 mg of anthocyanins and 3.85 mg/day of flavanols.
(These are the same flavonoids that abound in other berries, and in prunes, plums, grapes, cherries, dark chocolate, and red cabbage.)
They tested the rats by inducing them to navigate a “cross-maze” in search of rewarding food pellets, and scored them on accuracy and time taken:
- The young rats scored an average of 90 percent.
- The aged animals fed regular chow scored an average of 57 percent.
- The scores of the aged rats fed blueberry powder rose to an average of 83 percent after three weeks... almost as high as the young rats.
And the blueberry group’s amazing increase in accuracy persisted throughout the remainder of the treatment period.
Blueberries’ brain benefits: Picture is cloudy but becoming clearer
The apparent brain benefits of blueberries have been linked to their particular anthocyanins and flavanols.
Dietary flavonoids have been shown to cross the blood-brain barrier and exert positive effects on cognition and memory … but we’re a long way from knowing all the ways in which they enhance and protect brain tissues and function.
Researchers suspect that they enhance connections between brain cells (neurons), cellular communications, and stimulating regeneration of neurons.
Here’s how co-author Claire M Williams, Ph.D., described that aspect: “Dietary intervention studies … using flavanol/anthocyanin-rich plant or food extracts have indicated an ability of these dietary components to improve memory and learning, possibly by protecting vulnerable neurons, enhancing existing neuronal function or by stimulating neuronal regeneration.”
(These diet studies include human trials in addition to cell and animal experiments.)
And recent experimental results from her colleagues at the University of Reading show that berry flavonoids protect the brain against inflammation and damaging free radicals (Vauzour D et al. 2007 and 2008; Vafeiadou K et al. 2007; Pollard SE et al. 2006).
The UK team plans to explore the effects of diets rich in flavonoids on people suffering from Alzheimer's disease and other forms of cognitive decline.
- Pollard SE, Kuhnle GG, Vauzour D, Vafeiadou K, Tzounis X, Whiteman M, Rice-Evans C, Spencer JP. The reaction of flavonoid metabolites with peroxynitrite. Biochem Biophys Res Commun. 2006 Dec 1;350(4):960-8. Epub 2006 Oct 2.
- Vafeiadou K, Vauzour D, Spencer JP. Neuroinflammation and its modulation by flavonoids. Endocr Metab Immune Disord Drug Targets. 2007 Sep;7(3):211-24. Review.
- Vauzour D, Ravaioli G, Vafeiadou K, Rodriguez-Mateos A, Angeloni C, Spencer JP. Peroxynitrite induced formation of the neurotoxins 5-S-cysteinyl-dopamine and DHBT-1: Implications for Parkinson's disease and protection by polyphenols. Arch Biochem Biophys. 2008 Mar 22; [Epub ahead of print]
- Vauzour D, Vafeiadou K, Corona G, Pollard SE, Tzounis X, Spencer JP. Champagne wine polyphenols protect primary cortical neurons against peroxynitrite-induced injury. J Agric Food Chem. 2007 Apr 18;55(8):2854-60. Epub 2007 Mar 24.
- Vauzour D, Vafeiadou K, Spencer JP. Inhibition of the formation of the neurotoxin 5-S-cysteinyl-dopamine by polyphenols. Biochem Biophys Res Commun. 2007 Oct 19;362(2):340-6. Epub 2007 Aug 7.
- Williams CM, El Mohsen MA, Vauzour D, Rendeiro C, Butler LT, Ellis JA, Whiteman M & Spencer JPE (2008). Blueberry-induced changes in spatial working memory correlate with changes in hippocampal CREB phosphorylation and BDNF levels. Free Radical Biology & Medicine. Manuscript Number: FRBM-D-07-00468R2
- Williams CM. Accessed online April 20, 2008 at http://www.personal.reading.ac.uk/~sxs00cmw/