Protective properties of green tea uncovered

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Public release date: 5-Jan-2011

Contact: Dr. Ed Okello

e.j.okello@...

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Newcastle University

Protective properties of green tea uncovered

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

ish Crop Research Institute in Dundee, who developed technology

which simulates the human digestive system.

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 cells.

When ingested, the polyphenols are broken down to produce a mix of

compounds and it was these the Newcastle team tested 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, "

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 today. "

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 important. "

http://www.eurekalert.org/pub_releases/2011-01/nu-ppo010511.php