A new study shows drinking apple juice may improve memory by preventing the decline of an essential neurotransmitter known as acetylcholine.
Neurotransmitters are chemicals released by nerve cells to transmit messages to other nerve cells. They are critical for good memory and brain health. Previous studies have shown that increasing the amount of acetylcholine in the brain can slow the mental decline found in people with Alzheimer's disease.
"The findings of the present study show that consumption of antioxidant-rich foods such as apples and apple juice can help reduce problems associated with memory loss," says researcher Thomas Shea, Ph.D., director of the Center for Cellular Neurobiology & Neurodegeneration Research at the University of Massachusetts Lowell, in a news release.
Prior research has shown that supplementing animal diets with other antioxidant-rich fruits and vegetables, such as blueberries, spinach, and strawberries, can help slow age-related mental decline better than using dietary supplements containing purified forms of antioxidants.
Apples for Alzheimer's?
In the study, researchers compared normal adult mice, normal "aged" mice, and special mice that were a genetic model for human Alzheimer's.
The mice were given either a normal diet, or a diet lacking in essential nutrients, for one month. Some of the mice on the nutrient-poor diet were also given apple juice concentrate mixed in their water.
The results showed that normal adult mice and the genetically-engineered mice on normal diets had the same acetylcholine levels.
In fact, the normal adults had the same acetylcholine levels regardless of diet.
However, the genetically engineered mice on the nutrient-poor diet had lower acetylcholine levels. But this drop was prevented in those given apple juice.
In the aged mice on a normal diet, acetylcholine levels were lower than in the normal adult mice; and their levels were even lower if placed on the nutrient-poor diet. But, again, this decline was prevented by the addition of apple juice to drink.
The mice were also put through maze memory tests. "It was surprising how the animals on the apple-enhanced diets actually did a superior job on the maze tests than those not on the supplemented diet," says Shea.
The amount of apple juice the mice drank was comparable to drinking about two 8-ounce glasses of apple juice or eating two to three apples a day for humans.
Human studies looking at apple consumption are coming in the future.
The study was funded by an unrestricted grant from the U.S. Apple Association and the Apple Products Research & Education Council.
SOURCES: Chan, A. Journal of Alzheimer's Disease, August 2006; vol 9. News release, U.S. Apple Association.
By Jennifer Warner
Reviewed by Louise Chang, M.D.
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