January 1, 2005
We've all heard the saying, "An apple a day keeps the doctor away." Now, new scientific research shows just how important the apple may be. The popular fruit, researchers at Cornell University report, contains potent compounds that appear to protect the brain from damage and may even help to ward off Alzheimer's disease.
Food scientists believe the magic ingredient in apples is a plant pigment called quercetin. This natural substance is a disease-fighting antioxidant that protects cells throughout the body, including the brain. Past studies suggest that getting plenty of quercetin, abundant in the everyday apple, may protect the heart and blood vessels and possibly protect against cancer. This latest research points to quercetin as a potent protector of brain cells that may fight the devastating memory decline of Alzheimer's disease.
"On the basis of serving size, fresh apples have some of the highest levels of quercetin when compared to other fruits and vegetables and may be among the best food choices for fighting Alzheimer's," says study leader Chang Y. Lee, who has been studying the benefits of apples and other foods for some 20 years. "People should eat more apples, especially fresh ones."
Quercetin is abundant in the flesh and especially the skins of all types of fresh apples, from red delicious to Granny Smith's. Processed foods like applesauce or apple juice may not be as rich in the brain-protecting substance because they may omit the quercetin-rich skins. In addition to quercetin, apples likely contain a medley of additional substances important for health and well-being.
In this latest research, Lee and his colleagues exposed rat brain cells to varying amounts of quercetin or vitamin C, a well-established antioxidant and disease fighter. The brain cells were then exposed to hydrogen peroxide, a substance that can mimic some of the kinds of cell damage that occurs in the brains of those with Alzheimer's disease. The cells that had been treated with quercetin showed significantly less damage than the vitamin-C treated cells or brain cells that did not get any antioxidant protection.
Scientists are not sure exactly how the quercetin in apples protects brain cells in the lab, although its antioxidant effects are thought to neutralize cell-damaging compounds called free radicals. Other foods that are rich in quercetin, such as onions, blueberries, cranberries, and tea, may also afford protection against Alzheimer's. Indeed, another recent study reported that drinking tea may also have benefits for the brain and memory. [See the article, "Can a Cup of Tea a Day Keep Alzheimer's at Bay?"] Quercetin is also sold in nutritional supplements. The apple, however, remains at the top of the list when it comes to natural sources for disease-fighting quercetin.
Will an apple a day indeed keep Alzheimer's at bay? Nobody knows for sure. It's a long way from brain cells in the lab to the multi-faceted world of living people. Nutrition experts agree, however, that apples are an excellent addition to any healthful diet. Much more research on animals and people is needed to unravel the mysteries of the brain and the possible benefits of foods like the apple. Genetics and many environmental factors likely have an influence on who develops a complex illness like Alzheimer's, and likely many factors interact to help keep the brain alert and functioning well.
The Fisher Center for Alzheimer's Foundation continues to fund groundbreaking research into the causes of Alzheimer's, a disease that is estimated to strike tens of millions of baby boomers in the coming years. For more on how the Fisher Center is searching for a cure, visit www.ALZinfo.org.
Chang Y. Lee, et al: Journal of Agricultural and Food Chemistry, December 2004. (Volume 52, Number 24).
Heo HJ, Kim DO, Choi SJ, Shin DH, Lee CY. 2004. "Apple Phenolics Protect in Vitro Oxidative Stress-induced Neuronal Cell Death." Journal of Food Science, 69(9):S357-60.