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A chemical found in apples could protect the brain from the type of damage that triggers such neurodegenerative diseases as Alzheimer's and Parkinson's, according to research conducted by Cornell University food scientists.
The studies show that the chemical quercetin, a major flavanoid in apples, appears to be largely responsible for protecting rat brain cells when assaulted by oxidative stress in laboratory tests.
"The studies show that additional apple consumption not only may help reduce the risk of cancer, as previous studies have shown, but also that an apple a day may supply major bioactive compounds, which may play an important role in reducing the risk of neurodegenerative disorders," said researcher Chang Lee, professor of food science at Cornell University.
As reported in the December issue of the Journal of Agricultural and Food Chemistry, Lee and co-author Ho Jin Heo, a visiting fellow at Cornell, looked specifically at the chemical quercetin in apples and found that it appeared to be the main agent responsible for the beneficial effect.
In fact, the researchers found that quercetin works even better in protecting nerve cells against hydrogen peroxide than vitamin C, a naturally occurring antioxidant known to help prevent cell and tissue damage from oxidation.
Although Lee stresses that his studies were conducted in the laboratory, not in clinical trials with humans, he has no hesitation in recommending more apples in the diet as well as other fresh fruits and vegetables. "Indeed, I have a reason to say an apple a day keeps the doctor away," he said.
The researchers used red delicious apples grown in New York state to provide the extracts used in the study, but the beneficial chemical is present in all apple flesh and skin.
Even though quercetin is relatively stable during cooking, Lee said fresh apples are better sources of quercetin than cooked or processed apple products because the compound is mainly concentrated in the skin of apples rather than the flesh. Products such as apple juice and apple sauce do not contain significant amounts of skin. In general, red apples tend to have more of the antioxidant than green or yellow ones, although any apple variety is a good source of quercetin, he added.
For those who don’t like apples or may have difficulty eating the whole fruit, there are some promising alternatives, Lee suggests. Other foods containing high levels of quercetin include onions, which have some of the highest levels of quercetin among vegetables, as well as berries, particularly blueberries and cranberries. Like other antioxidants, quercetin has been associated with an increasing number of potential health benefits, including protection against cancer.
Source: Medical Week staff, week of November 20, 2004
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