Berry Good Food for the Brain

Diets high in antioxidant foods appear to protect the brain against oxidative damage, if rat studies by Agricultural Research Service and University of Denver scientists are any indication. Oxidative damage is thought to lead to age-related dysfunctions such as loss of memory or motor coordination.

In the studies, rats that ate extracts of strawberries, blueberries or spinach as part of their daily diet fared far better on brain cell function tests than the animals getting chow alone. The fruit and vegetable extracts offered at least as much protection as vitamin E against oxidative damage, an ARS scientist said yesterday at the Experimental Biology 97 meeting in New Orleans.

Earlier, these foods scored highest among commonly eaten fruits and vegetables in a test-tube assay of total antioxidant capacity. The next step was to assess their protective power in animals. So the scientists added either strawberry extract, vitamin E or nothing to the rats’ normal diet for eight weeks. Then they put the animals in chambers under 100 percent oxygen for two days. They later repeated the study using blueberry and spinach extracts.

High oxygen exposure alters brain function in young rats in a manner similar to the aging process. In both cases, brain cells are less sensitive to neurotransmitters, such as dopamine or norepinephrine, that prompt them to send or stop sending information.

The scientists measured responses of three different types of brain function controlling memory, movement and growth of nerve cells. In all three cases, decline in these functions due to oxygen exposure was significantly--often dramatically--reduced by strawberry extract as well as by vitamin E.

Preliminary data indicates that blueberry extract provides even more protection to rats’ brains. If this finding holds up, it supports the usefulness of the chemical assay--known as ORAC--for identifying health-promoting foods because blueberries had the highest antioxidant capacity of the fruits and vegetables tested.

Scientific contact: James A. Joseph, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts, Boston, Mass., phone (617) 556-3178, joseph_ne@hnrc.tufts.edu.