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Green tea compound Alzheimer hope
An ingredient of green tea may help to protect the brain against the ravages
of Alzheimer's disease, research in the US suggests.
Sep 05
BBC Online
University of South Florida scientists found the component prevented
Alzheimer's-like damage in the brains of mice bred to develop symptoms.
The component - EGCG - is already strongly suspected of offering protection
against certain cancers.
The study is published in the Journal of Neuroscience.
It provides evidence that EGCG decreases production of the beta-amyloid
protein thought to play a key role in the development of Alzheimer's
symptoms.
A new generation of dietary supplements containing pure EGCG may lead to the
greatest benefit for treating Alzheimer's disease
Dr Doug Shytle
It is this protein that forms the characteristic plaques found in the brain
of Alzheimer's patients which are thought to lead to nerve damage and memory
loss.
After treating Alzheimer's mice for several months with daily injections of
pure EGCG, the researchers observed a dramatic decrease - as much as 54% -
of brain-clogging Alzheimer's plaques.
Lead researcher Dr Jun Tan said: "The findings suggest that a concentrated
component of green tea can decrease brain beta-amyloid plaque formation.
"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."
Green tea contains many antioxidants, including those known as flavonoids,
that can protect against damage to the brain caused by charged particles
called free radicals.
However, the Florida team showed that other flavonoids in green tea actually
block EGCG's ability to prevent the harmful build up of beta-amyloid.
Thus drinking green tea alone would not likely have a beneficial effect.
Supplements
Dr Doug Shytle, who also worked on the study, said: "This finding suggests
that green tea extract selectively concentrating EGCG would be needed to
override the counteractive effect of other flavonoids found in green tea."
"A new generation of dietary supplements containing pure EGCG may lead to
the greatest benefit for treating Alzheimer's disease."
Humans would need a daily dose of 1,500 to 1,600 mg of EGCG to approximate
the level that had a positive impact on mice.
That dosage has already been studied in healthy human volunteers and was
found to be safe and well tolerated.
The Florida team now plans to study whether multiple oral doses of EGCG can
reduce memory loss in Alzheimer's mice as well as reducing plaque formation.
Harriet Millward, of the Alzheimer's Research Trust, told the BBC News
website: "This is quite encouraging progress, building on previous evidence
that antioxidants in green tea might be beneficial to Alzheimer's patients
either as treatment or prevention."
However, Dr Millward said the role of beta-amyloid in the brain was not well
understood, and reducing levels too far might cause damage.
It was also not clear whether the formation of plaques was a cause of
Alzheimer's, or just an effect of it.
Dr Susanne Sorensen, of the Alzheimer's Society, said: "It is valuable to
identify any compound that may halt the development of amyloid plaques,
which are found in the brains of people with Alzheimer's disease.
"Especially as there is currently no cure for Alzheimer's disease.
"However, more research is needed before it is possible to recommend the
compound found in green tea as a treatment for Alzheimer's disease in
humans."
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Cup of tea may help boost memory
Drinking regular cups of tea could help improve your memory,
research suggests.
A team from Newcastle University found green and black tea inhibited
the activity of key enzymes in the brain associated with memory.
The researchers hope their findings, published in Phytotherapy
Research, may lead to the development of a new treatment for
Alzheimer's Disease.
They say tea appears to have the same effect as drugs specifically
designed to combat the condition.
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Although there is no cure for Alzheimer's, tea could potentially be
another weapon in the armoury. Dr Ed Okello
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Alzheimer's disease is associated with a reduced level of a chemical
called acetylcholine in the brain.
In lab tests, the Newcastle team found that both green and black tea
inhibited the activity of the enzyme acetylcholinesterase (AChE),
which breaks down this key chemical.
They also found both teas inhibited the activity of a second enzyme
butyrylcholinesterase (BuChE), which has been discovered in protein
deposits found in the brain of patients with Alzheimer's.
Green tea went one step further in that it obstructed the activity of
beta-secretase, which plays a role in the production of protein
deposits in the brain which are associated with Alzheimer's disease.
The scientists also found that it continued to have its inhibitive
effect for a week, whereas black tea's enzyme-inhibiting properties
lasted for only one day.
Drugs work same way
There is no cure for Alzheimer's but it is possible to slow the
development of the disease.
Drugs currently on the market hinder the activity of AChE, and others
are being developed which scientists hope will inhibit the
activity of BuChE and beta-secretase.
However, many of the drugs currently available, such as donepezil, have
unpleasant side effects and the medical profession is keen to find
alternatives.
The Newcastle University researchers are now seeking funding to carry
out further tests on green tea, which they hope will include clinical
trials.
Their aim is to work towards the development of a medicinal tea which
is specifically aimed at Alzheimer's sufferers.
The next step is to find out exactly which components of green tea inhibit
the activity of the enzymes AChE, BuChE and beta-secretase.
Lead researcher Dr Ed Okello said: "Although there is no cure for
Alzheimer's, tea could potentially be another weapon in the armoury
which is used to treat this disease and slow down its development.
"It would be wonderful if our work could help improve the quality of
life for millions of sufferers and their carers.
"Our findings are particularly exciting as tea is already a very
popular drink, it is inexpensive, and there do not seem to be any
adverse side effects when it is consumed.
"Still, we expect it will be several years until we are able to
produce anything marketable."
Professor Clive Ballard, director of research, Alzheimer's Society,
said: "This interesting research builds on previous evidence that
suggests that green tea may be beneficial due to anti-oxidant
properties.
"Certainly the effect on the cholinesterase enzyme (the target of
current anti-dementia drugs such as Aricept) and beta-secretase (an
enzyme which is important in the build up of plaques) is very
exciting and requires further investigation."
Black tea - traditional English breakfast tea - is derived from the
same plant as green tea, Camellia sinensis, but has a different taste
and appearance because it is fermented.
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