Protective Properties of Green Tea Uncovered by ScienceDaily
Regularly drinking green tea could protect the brain against
developing Alzheimer's and other forms of dementia, according to
latest research by scientists at Newcastle University.
The study, published in the academic journal
Phytomedicine, also suggests this ancient Chinese remedy
could play a vital role in protecting the body against cancer.
Led by Dr Ed Okello, the Newcastle team wanted to know if 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.
Digestion is a vital process which provides our bodies with the
nutrients we need to survive. But, says Dr Okello, it also means
that just because the food we put into our mouths is generally
accepted to contain health-boosting properties, we can't assume
these compounds will ever be absorbed by the body.
"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,"
explains 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 tumour cells which we were using in our experiments."
As part of the research, 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, who developed technology which simulates the human
It is this which made it possible for the team to analyse the
protective properties of the products of digestion.
Two compounds are known to play a significant role in the
development of Alzheimer's disease -- hydrogen peroxide and a
protein known as beta-amyloid.
Previous 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
When ingested, the polyphenols are broken down to produce a mix
of compounds and it was these the Newcastle team tested in their
"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," explains 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."
Carrying out the experiments in the lab using a tumour cell
model, they 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
The next step is to discover whether the beneficial compounds
are produced during digestion after healthy human volunteers
consume tea polyphenols. The team has already received funding from
the Biotechnology and Biological Sciences Research Council (BBSRC)
to take this forward.
Dr Okello adds: "There are obviously many factors which together
have an influence on diseases such as cancer and dementia -- a good
diet, plenty of exercise and a healthy lifestyle are all
The above story is reprinted (with editorial
adaptations by ScienceDaily staff) from materials provided
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