Brain-boosting blueberries

The link between diet, specifically antioxidants, and brain health gained further ground last week with new studies suggesting that antioxidant-rich blueberries can both help fight aging and reduce some of the functional damage caused by brain injury.

Researchers at the Universidad Nacional Autónoma de Mexico (UNAM) and the University of Houston-Clear Lake (UHCL) reported at last week's Society for Neuroscience meeting that a blueberry-enriched antioxidant diet prevents an age-related increase in a protein (NF-kappaB) that responds to oxidative stress, a probable cause of brain ageing. Two years ago the same team had shown such a diet to prevent age-related deterioration of object recognition memory in aged rats.

"Our findings fit into an emerging pattern of data from many laboratories that point to a buildup of oxidative damage as one of the key factors in brain ageing,"​ said Pilar Goyarzu, a doctoral student at UNAM under the direction of Dr David Malin and Francis Lau. "The findings also suggest that diets rich in natural antioxidants have the potential to slow down this damage."​

For the current study, Goyarzu fed rats a blueberry-enriched diet. NF-kappaB levels were then assayed in five different brain regions involved in memory processes (the hippocampus, frontal cortex, striatum, basal forebrain, and cerebellum). The aged rats on the blueberry-enriched diet had lower NF-kappaB levels than aged rats fed a control data. Young control rats also had lower NF-kappaB levels than the aged control rats.

"We also found that among the aged rats, the higher the NF-kappaB levels, the poorer their memory scores,"​ said Goyarzu. The researchers are now studying the effects of ageing and diet on other proteins that mediate the effects of oxidative stress in the brain.

A second study presented at the conference by the US National Institute on Aging's (NIA) Gerontology Research Center in Baltimore, Maryland, found that blueberries can help lessen some of the functional damage caused by a brain injury.

"Our results suggest that the consumption of blueberries and perhaps other fruits and vegetables could have a positive neurological impact on the aging brain, Alzheimer's disease, and other neurological disorders,"​ said Edward Spangler, the lead author of the study.

Spangler and his colleagues fed one group of young rats a diet supplemented with a 2 per cent blueberry extract; another group was fed the same diet, but without the extract. After two to three months, all the animals received chemically-induced lesions in their hippocampus, a region deep within the brain that plays an essential role in learning and memory. Damage to the hippocampus results in an inability to remember recent events.

The researchers then tested the animals' ability to learn a complicated maze task. The rats that had been fed the blueberry extract were significantly less impaired at performing the task than those that did not receive the extract.

"We believe the blueberries contain a particular group of as-yet unidentified bioactive chemicals that ameliorate the functional consequences of brain damage, including a loss of the ability to learn or remember recent events,"​ said Spangler.

A third study, by researchers at the University of Maryland and the US Department of Agriculture in Boston, found that an antioxidant-rich diet may help stave off the harmful, immediate effects of certain cosmic radiation, findings which could help protect future astronauts from the dangerous effects produced by extended radiation exposure on long-term space missions, they said.

A three-year European-funded collaborative research project, begun in 2000, is currently investigating the functional properties of anthocyanins, the compounds that give berries their colour, and their influence on heart disease.

The new studies were reported last week during the Society for Neuroscience​ meeting, held in New Orleans, LA.