Green Tea May Protect Brain Against Alzheimer's

Regularly drinking green tea could protect the brain against developing Alzheimer's disease (AD) and other types of dementia. The study also suggests this ancient Chinese remedy could play a key role in protecting the body against cancer.

Led by Dr. Ed Okello, and colleagues from Newcastle University (Newcastle upon Tyne, UK), the researchers set out to determine whether the protective properties of green tea--which have previously been shown to be present in the undigested, freshly brewed form of the drink--were still active once the tea had been digested.

"What was really exciting about this study was that we found when green tea is digested by enzymes in the gut, the resulting chemicals are actually more effective against key triggers of Alzheimer's development than the undigested form of the tea,” explained Dr. Okello, based in the School of Agriculture, Food, and Rural Development at Newcastle University. "In addition to this, we also found the digested compounds had anti-cancer properties, significantly slowing down the growth of the tumor cells which we were using in our experiments.”

As part of the study, the Newcastle team worked in collaboration with Dr. Gordon McDougall of the Plant Products and Food Quality Group at the Scottish Crop Research Institute in Dundee (UK), who developed technology that simulates the human digestive system. This made it possible for the team to analyze the protective properties of the products of digestion.

Two compounds are known to play a significant role in the development of AD--hydrogen peroxide and a protein known as beta-amyloid. Earlier studies have shown that compounds known as polyphenols, present in black and green tea, possess neuroprotective properties, binding with the toxic compounds, and protecting the brain cells.

When ingested, the polyphenols are broken down to generate a mix of compounds, which were tested by the Newcastle team in their latest research. "It's one of the reasons why we have to be so careful when we make claims about the health benefits of various foods and supplements,” explained Dr. Okello. "There are certain chemicals we know to be beneficial and we can identify foods which are rich in them but what happens during the digestion process is crucial to whether these foods are actually doing us any good.”

Performing the experiments in the lab using a tumor cell model, the scientists exposed the cells to varying concentrations of the different toxins and the digested green tea compounds. Dr. Okello explained, "The digested chemicals protected the cells, preventing the toxins from destroying the cells. We also saw them affecting the cancer cells, significantly slowing down their growth. Green tea has been used in traditional Chinese medicine for centuries and what we have here provides the scientific evidence why it may be effective against some of the key diseases we face today.”

The study's findings were published online ahead of print December 21, 2010, in the journal Phytomedicine.

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