Navigation Links
Green tea boosts production of detox enzymes, rendering cancerous chemicals harmless
Date:8/13/2007

PHILADELPHIA − Concentrated chemicals derived from green tea dramatically boosted production of a group of key detoxification enzymes in people with low levels of these beneficial proteins, according to researchers at Arizona Cancer Center.

These findings, published in the August issue of Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research, suggest that a green tea concentrate might help some people strengthen their metabolic defense against toxins capable of causing cancer.

In a study of 42 people, the concentrate − composed of chemicals known as green tea catechins in amounts equal to that found in 8-16 cups of green tea − boosted production of the enzymes, which belong to the glutathione S-transferase (GST) family, by as much as 80 percent in some participants.

GST enzymes are believed to be crucial to the bodys defense against cancer-causing chemicals and other toxins, according to the studys lead investigator, H.-H. Sherry Chow, Ph.D., a research associate professor at the University of Arizona. They modify the cancer-causing molecules that would otherwise damage cellular DNA, thus rendering them inert.

They actually convert known carcinogens to non-toxic chemicals, and studies have shown a correlation between deficient expression of these enzymes and increased risk of developing some cancers, Chow said.

Expression of this enzyme varies dramatically in people due to genetic variation and environmental factors, Chow added. Green tea catechins somehow increase gene expression of these enzymes, which can be an advantage to people with low levels to start with.

Green tea has long been of interest to researchers given studies that have shown populations in which it is often consumed, such as the Chinese and Japanese, generally have lower rates of cancer. To find out if green tea can protect against cancer, the NCI has sponsored a number of rigorous scientific studies testing capsules of the extract, Polyphenon E, that have been prepared in Japan to meet exact specifications. These pills contain epigallocatechin gallate (EGCG), a catechin known for its potent antioxidant activity, and are currently being tested against a variety of cancers in clinical trials.

This study was designed to see if green tea catechin concentrate had any effect on the levels of GST enzymes in healthy individuals − research that could explain the teas anti-cancer properties. Healthy volunteers were asked to abstain from consuming any tea or tea-related products for four weeks. At the end of this washout period, blood was drawn and baseline GST enzyme levels were determined for each participant. Then, the volunteers were asked to take four Polyphenon E capsules, for a total of 800 milligrams of EGCG, each morning on an empty stomach for four weeks and to abstain from drinking tea or eating many cruciferous vegetables, which contain other beneficial chemicals. Another blood sample was taken after four weeks, and GST activity was determined.

Researchers found that use of Polyphenon E enhanced GST activity when data from all participants were included for analysis. But it had its most significant effect in volunteers whose baseline blood measurements showed low GST activity − an 80 percent increase compared to baseline GST activity. Activity did not change in volunteers with medium GST expression, or in those with the highest levels, GST seemed to decrease slightly although researchers believe that decline was due to random variation.

This is the first clinical study to show proof that chemicals in green tea can increase detoxification enzymes in humans, Chow said. There may be other mechanism in play by which green tea may protect against cancer development, but this is a good place to start.


'/>"/>
Contact: Greg Lester
lester@aacr.org
267-646-0554
American Association for Cancer Research
Source:Eurekalert

Related biology news :

1. New research indicates a troubled greenhouse is brewing
2. Genetic defects give the immune system the green light to attack the pancreas
3. While on trail of dioxin, scientists pinpoint cancer target of green tea
4. UN successfully tests green pesticide against locusts
5. Green catalyst destroys pesticides and munitions toxins, finds Carnegie Mellon University
6. Bacteria are key to green plastics, drugs
7. New tools used to control foodborne hepatitis A outbreaks related to green onions
8. Green diesel: New process makes liquid transportation fuel from plants
9. FDA: Highly Unlikely Green Tea Lowers Cancer Risk
10. Microbes under Greenland Ice may be preview of what scientists find under Mars surface
11. Asleep in the deep: Model helps assess ocean-injection strategy for combating greenhouse effect
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:11/22/2016)... MINNETONKA, Minn. , Nov. 22, 2016   ... that supports the entire spectrum of clinical research, is ... by Medical LiveWire Healthcare and Life Sciences Awards ... This award caps off an unprecedented year of recognition ... clinical trials for over 15 years. iMedNet ...
(Date:11/16/2016)... , Nov. 16, 2016 Sensory Inc ... and security for consumer electronics, and VeriTran ... and retail industry, today announced a global partnership ... way to authenticate users of mobile banking and ... TrulySecure™ software which requires no specialized biometric ...
(Date:6/27/2016)... 27, 2016 Research and Markets has announced ... report to their offering. ... to grow at a CAGR of 12.28% during the ... on an in-depth market analysis with inputs from industry experts. The ... coming years. The report also includes a discussion of the key ...
Breaking Biology News(10 mins):
(Date:11/30/2016)... Nov. 30, 2016  The Allen Institute for ... the first publicly available collection of gene edited, ... target key cellular structures with unprecedented clarity. Distributed ... powerful tools are a crucial first step toward ... understand what makes human cells healthy and what ...
(Date:11/30/2016)... , Nov. 30, 2016  Tempus, a ... cancer care, and Penn,s Abramson Cancer Center have ... a positive response to immunotherapy treatment based on ... As part of a research collaboration, Tempus ... and melanoma cancer patient data to Penn. Utilizing ...
(Date:11/30/2016)... , 30. November 2016   Merck ... heute die Unterzeichnung einer Reihe von Vereinbarungen ... wird Evotec AG Screeningleistungen für Mercks Palette ... Der Zugriff auf diese Bibliotheken in Kombination ... einen schnelleren Weg zur Ermittlung und Erforschung ...
(Date:11/30/2016)... --  Merck , a leading science and technology company, ... of agreements with Evotec AG, whereby Evotec AG will ... such as CRISPR and shRNA libraries. Combining access to ... pathway to explore and identify new drug targets. ... targets, a process that can be time- and labor-intensive," ...
Breaking Biology Technology: