Green tea could provide Alzheimer's breakthrough
21/09/2005 - Scientists investigating the effects of green tea antioxidant EGCG on mice's brains believe their positive results may signal its use as a preventative or treatment of Alzheimer's disease in humans.
EGCG (epigallocatechin-3-gallate) is the most potent antioxidant polyphenol in green tea and has been repeatedly studies in labs for its purported anti-cancer effect.
Ingredients companies DSM and Taiyo have isolated EGCG and offer it in highly purified form to food and supplements manufacturers.
The new study, published today in the Journal of Neuroscience, will certainly be of interest to them, especially as the researchers say that the effects they observed in their study may not be brought about by drinking green tea, but that pure EGCG extract may be required.
The team from the University of South Florida gave daily EGCG injections (20mg/kg) to a group of five mice that were specially bred to be Alzheimer's prone over a period of 60 days, beginning when they were 12 months old. Another five-strong group of mice was injected with a control substance in place of the EGCG.
When the mice's brains were studied, those that had received the EGCG had greatly reduced build up of beta-amyloid ? in some cases as much as 54 percent ? compared to the control mice. When it causes plaque in the brain, this protein can lead to nerve damage and memory loss typical of the progressive, neurodegenerative disorder Alzheimers disease.
These results confirmed earlier observations when mice's brains were treated with EGCG and studied in vitro.
"The findings suggest that a concentrated component of green tea can decrease brain beta-amyloid plaque formation," said senior study author Dr Jun Tan.
"If beta-amyloid pathology in this Alzheimer's mouse model is representative of Alzheimer's disease pathology in humans, EGCG dietary supplementation may be effective in preventing and treating the disease."
For humans, 1500 to 1600mg of EGCG a day would be the equivalent to the injection dosage seen to benefit the Alzheimer's mice.
But before consumers dash out to stock up on green tea, the researchers warn that other flavonoids present in the beverage could counter EGCG's beneficial effect.
However this could prove to be a boon for the dietary supplements industry. Co-author Doug Shytle said: "A new generation of dietary supplements containing pure EGCG may lead to the greatest benefit for treating Alzheimer's disease."
The team plans to extend its investigation by administering oral doses of EGCG to mice and assessing whether they can improve memory loss as well as reducing plaque.
If this investigation delivers positive results the authors said they "believe clinical trials of EGCD to treat Alzheimer's disease would be warranted".
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