By J. Raloff
The body creates oxidants, chemically reactive molecular fragments, to eliminate old cells, infectious agents, and damaged tissue. When all goes well, natural antioxidants quickly step in to limit the process before it gets out of hand. As animals age, however, their antioxidant production wanes. Indeed, oxidation underlies many degenerative changes that come with aging (SN: 8/10/96, p. 95).
Last year, chemists at the Agriculture Department’s Human Nutrition Research Center on Aging (HNRCA) at Tufts University in Boston found that blueberries are a rich source of pigments, called flavonoids, that show strong antioxidant activity. Their earlier data showed that spinach and strawberries contain copious amounts of other antioxidants.
Colleagues in a neighboring lab have now supplemented the standard rodent food with a powdered form of blueberries, strawberries, or spinach. The researchers added the supplements in amounts having equal antioxidant activity. Ten 19-month-old rats received each type of supplemented rations. In terms of life span, these animals were on par with people in their 60s.
After 8 weeks, the scientists put each animal through a number of tests. These included mazes, walking a narrow plank, and balancing on a spinning rod. Afterward, the researchers removed and examined each animal’s brain.
Though all supplemented animals performed better on memory tests than the 10 rats that got undoctored chow, only the blueberry group showed notable improvements over the control group in every test of motor coordination. James A. Joseph of HNRCA and his colleagues report their findings in the Sept. 15 Journal of Neuroscience.
After eating blueberry-laced chow for 2 months, 21-month-old animals outperformed unsupplemented, younger rats, Joseph says. "So, we got reversals in age-related declines." The blueberries that each animal downed were equivalent, when adjusted for body weight, to 1 cup daily in a person’s diet, he notes.
The scientists measured a variety of chemical-signaling characteristics in each rat’s striatum, a brain region pivotal to coordination. Each supplement showed a different benefit pattern, Joseph says, suggesting that blueberries’ protectiveness may trace to more than oxidant quenching.
"A next important step in the research will be to see if the improvements are long lasting," says Molly Wagster of the National Institute on Aging in Bethesda, Md., which funded the study in part.
The differential benefits seen with the three diets reinforce what many other recent studies have suggested: "All antioxidants aren’t alike," observes William A. Pryor of Louisiana State University in Baton Rouge. Some reach different places in the body; others do more than halt oxidation, he says.
It’s therefore important, he argues, not to rely on supplements containing a single antioxidant, such as vitamin E. "You’ve still got to eat plenty of different fruits and vegetables," Pryor says. Since pigments can be very potent antioxidants, he prizes deeply colored foods—especially "anything blue."
From Science News, Vol. 156, No. 12, September 18, 1999, p. 180. Copyright © 1999, Science Service.