Green Tea May Help Prevent Alzheimer’s Disease
Study Shows Green Tea May Also Slow Growth of Cancer Cells
By Bill Hendrick
WebMD Health News
Reviewed by Laura J. Martin, MD
woman drinking green tea

Jan. 6, 2011 -- Regular consumption of green tea may offer protection against Alzheimer’s disease and other dementias and may also slow growth of cancer cells, new research indicates.

Green tea, an ancient Chinese remedy, has been shown to have protective properties in undigested, freshly brewed forms. But a research team at Newcastle University in the U.K. set out to determine whether the protective substances remained active after digestion. And in the study, they did.

“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,” Ed Okello, of Newcastle, says in a news release. “In addition to this, we also found the digested compounds had anti-cancer properties, significantly slowing down the growth of tumor cells which we were using in our experiments.”

Two compounds that are known to play a major role in the development of Alzheimer’s are hydrogen peroxide and beta-amyloid, a protein.

Previous research has shown that polyphenols, present in green and black tea, have neuroprotective properties, binding with the toxic compounds and protecting brain cells.

Polyphenols, when ingested, are broken down to produce a mixture of compounds, which the Newcastle scientists tested for this latest study.
Role of Digestion

“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,” Okello says.

The researchers exposed cells similar to neurons to varying concentrations of toxins, as well as digested tea compounds, and the digested tea chemicals protected the cells, preventing the toxins from destroying them.

“We also saw them affecting the cancer cells, significantly slowing down their growth,” he says. “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 researchers say there is plenty of evidence that both black and green teas have protective properties that mainly are attributable to their content of polyphenols.

Green tea has been shown to be effective against cancers in animal models, and epidemiological studies have suggested it reduces risk for prostate cancer in men.

The results of the study, while not definitive, do provide a basis for more research on green tea metabolites and their potential role in fighting Alzheimer’s disease.

The study is published in the journal Phytomedicine.