Main stories from 3 November 1997 Adelaidean

Monday, 3 November 1997

Green tea - a natural weapon against cholesterol?

Green tea has already been linked with beneficial effects such as a reduction in the risk of cancer. Now a new Adelaide study is examining how green tea could help people cut their cholesterol levels. Currently pharmaceuticals are the main agents used to lower people's blood cholesterol levels, in conjunction with a low-fat, low-cholesterol diet. But studies in Asia have shown that people can significantly decrease harmful cholesterol levels, and improve their chances of preventing heart disease, if they drink 5-10 cups of green tea every day.

Christina Bursill, a PhD student with the University of Adelaide's Department of Physiology (who is based at the CSIRO's Division of Human Nutrition under the supervision of Dr Paul Roach) is conducting her own examination of the benefits of green tea. For her honours work she found that extracts of the tea enable the so-called "bad" form of cholesterol, LDL, to be more actively removed from the blood. LDL, which is linked with heart disease, is taken out of the blood by receptor molecules on the outside of nearby cells. Once the cholesterol-containing particles bind with the LDL receptors, they can enter cells where they are broken down and the cholesterol used. Ms Bursill's research showed that antioxidants contained in green tea cause the acitvity of the LDL receptors in human liver cells to increase, thereby allowing a greater uptake of cholesterol from the blood into the cells.

"Cholesterol is essential for the integrity and development of all mammalian cells and is the raw material used in the synthesis of steroid hormones," Ms Bursill says. "But the very property that makes it useful, mainly insolubility in water, also makes it potentially lethal." If cholesterol collects within the wall of an artery, it can't be readily mobilised and its presence eventually leads to the development of masses which partially obstruct the passage of blood vessels. For cholesterol to be transported safely in the blood, its concentration must be kept low.

Ms Bursill's current research efforts are mostly concerned with finding out which constituents in green tea are responsible for lowering cholesterol and how they work. Australians aren't in the habit of drinking green tea, but considering that coronary heart disease kills 150 Australians every 24 hours, Ms Bursill believes it might be worthwhile if people started including green tea in their daily beverage consumption.


Contact Details

Dr Paul Roach
The University of Adelaide
Business: +61 8 8313 8821

Ms Robyn Mills
Media and Communications Officer
The University of Adelaide
Business: +61 8 8313 6341
Mobile: +61 410 689 084

Mr David Ellis
Deputy Director, Media and Corporate Relations
External Relations
The University of Adelaide
Business: +61 8 8313 5414
Mobile: +61 (0)421 612 762