An article published online on January 24, 2008 in the Journal of Food Science reported that the fruits most commonly consumed by Westerners and Asians, in addition to providing us with fiber, vitamins and minerals, may have a protective effect against the neurodegeneration that occurs in Alzheimer's disease.

Free radical formation induced by amyloid beta, a substance that forms in the brains of Alzheimer's patients, results in neurotoxicity that is believed to be responsible for the neuronal degeneration that takes place in the disease. Antioxidants from fruits and vegetables may help prevent some of this free radical activity, thereby helping to protect the brain.

C. Y. Lee of Cornell University and his Korean colleagues pretreated cultured neuron-like cells derived from rats with four concentrations of phenolics extracted from apples, bananas, and oranges. The cell cultures were then exposed to hydrogen peroxide, a well known inducer of oxidative stress.

Cell viability tests showed that all of the fruit extracts dose-dependently reduced neurotoxicity compared with cells that were treated with hydrogen peroxide alone. Apples showed the greatest benefits, with the highest concentration associated with the greatest increase in viability. Although the lowest concentration of banana showed less benefit than the lowest orange concentration, the highest concentration of banana demonstrated a greater effect than the highest concentration of orange.

"Our study demonstrated that antioxidants in the major fresh fruits consumed in the United States and Korea protected neuronal cells from oxidative stress," the authors conclude. "In addition, it has been reported that apple juice with antioxidative phytochemicals protected brain tissue against oxidative damage, and improved cognitive performance in genetically induced Alzheimer's disease mice. Therefore, additional consumption of fresh fruits such as apple, banana, and orange may be beneficial to improve effects in neurodegenerative diseases such as Alzheimer’s.”