Daily ingestion of EGCG led to a reduction in the weight of breast tumours in mice by 68 per cent, researchers from the University of Mississippi told attendees at the 121st Annual Meeting of the American Physiological Society, part of the Experimental Biology 2008 scientific conference.
In an email to NutraIngredients.com , lead researcher Jian-Wei Gu stated: "Epidemiology study has indicated that green tea and its extracts such as EGCG protect against progression of cancers including breast cancer.
However, the anti-cancer mechanisms of EGCG and green tea are poorly understood.
"We believe that this animal study provide a new insight mechanisms how green tea can suppress cancer progression," added Dr. Gu.
Green tea contains between 30 and 40 per cent of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3 and 10 per cent.
Oolong tea is semi-fermented tea and is somewhere between green and black tea.
The four primary polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG), epigallocatechin, epicatechin gallate, and epicatechin.
Tea time for mice Dr. Gu and co-workers used seven week-old female mice and divided them into two groups - one received EGCG in their drinking water at a dose of 25 mg per 50 ml, while the other received no EGCG in their drinking water, for five weeks.
The dose of EGCG was approximately equal to 50-100 mg per kg per day.
"The dosage in this animal study is not very high and this should be attainable in a dietary supplement," Gu told this website.
"However, we need further studies in humans."
During the second week of the study the left fourth mammary glands of the mice was injected with mouse breast cancer cells, a tumour progression monitored as a function of tumour size (as a measure of the tumour cross section area: TCSA), tumour weight, and levels of vascular endothelial growth factor (VEGF), a protein found in a variety of breast cancer types.
At the end of the study, mice in the EGCG group exhibited 66 per cent smaller tumours, with a 68 per cent decrease in weight.
Furthermore, levels of VEGF were significantly lower in the EGCG mice, compared to the control mice - 26.5 versus 40.8 pg per ml, respectively.
"In this study we have demonstrated that the frequent ingestion of EGCG significantly inhibits breast tumour growth, VEGF expression and tumour angiogenesis in mice," concluded Dr. Gu.
"We believe our findings will help lead to new therapies for the prevention and treatment of breast cancer in women."
Beyond cancer
In addition to the potential anti-cancer benefits, previous studies have reported a range of health benefits for green tea and its extracts, including the potential to promote weight loss, and protection against Alzheimer's.
European demand for tea extracts is currently surging, having reached 500 metric tonnes by 2003.
This has seen companies such as DSM, with its Teavigo boasting 95 per cent purity of EGCG, and Taiyo International, with its Sunphenon claiming more than 90 per cent purity, position themselves firmly in specific catechin markets.
Source: Experimental Biology 2008 121st Annual Meeting of the American Physiological Society "Oral Administration of EGCG, an Antioxidant Found in Green Tea, Inhibits Tumor Angiogenesis and Growth of Breast Cancer in Female Mice" Authors: J.-W. Gu, E. Young, J. Covington, J.W. Johnson, W. Tan