Blueberries May Be King of the Hill for Those Over the Hill
Sept. 16, 1999 (Atlanta) -- An apple a day may keep the doctor away, but a generous sprinkling of blueberries on your morning cereal may keep some of the signs of old age at bay -- at least if you are a rat. A study published in The Journal of Neuroscience shows that a diet high in blueberry extract appeared to reverse the mental, nerve, and muscle function decline in older rats.
"What we found was that especially the blueberry diet reversed some of the age-induced deficits in motor behavior [movements coordinated by nerves and muscles]. All the diets actually helped with cognitive, or learning and memory, behavior," co-author Barbara Shukitt-Hale, PhD, tells WebMD. Shukitt-Hale is a research psychologist at the U.S. Department of Agriculture (USDA) and at Tufts University in Medford, Mass. The USDA supported the study.
The researchers, led by James A. Joseph, PhD, also from the USDA and Tufts University, randomly assigned 40 19-month-old male rats to one of four diet groups: a regular diet, or a diet supplemented with either strawberry, spinach, or blueberry extract.
After 8 weeks, the rats -- the equivalent of 70-75 years in human terms, according to Shukitt-Hale -- were tested for motor function. They walked on a rod or a plank, or hung onto a wire. The rats were also tested for cognitive function by swimming through a water maze. Afterwards, researchers tested the amount of several brain chemicals, or neurotransmitters, in the rats.
The strawberry and spinach-supplemented groups showed some increases in tests measuring certain brain chemicals compared to rats with the regular diet. However, the blueberry group showed the greatest improvements in all areas. Also, the blueberry-supplemented rats were the only group to show reversals in motor behavioral deficits that these brain chemicals help control. All three supplemented groups showed significant improvements in the cognitive trials, while the regular diet group showed no improvements.
While the effects of the supplementation were relatively easy to measure, pinpointing the cause is more difficult. "We are trying to tease out ... the mechanism behind it," says Shukitt-Hale. Researchers suspect that certain foods, mainly fruits and vegetables, have ingredients called antioxidants that help the body withstand long-term damage. The damage, cell death and tissue loss, is thought to be the result of a natural process in the body called oxidative stress. In the study, blueberry and strawberry, but not spinach, supplementation appeared to protect the brain against oxidative stress, relative to the regular diet group.