Green Tea May Protect Against Breast Cancer

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Now it seems that the Western hemisphere is starting to take notice of this beverage’s potential health benefits. In particular, research on the health benefits of green tea progressed in leaps and pounds over the last few years.

Not just a cuppa

In 2007 Dr. Anna Wu, professor of preventive medicine at the Keck School of Medicine in the US, started to study the relationship between green tea consumption and breast cancer risk. At that stage Dr. Wu explained that an earlier study about breast cancer risk among Asian-American women showed that drinking green tea had a strong protective effect against breast cancer, while the more commonly consumed black tea had no effect at all. This small pilot study suggested that regular green tea drinkers had lower blood oestrogen levels, while regular black tea drinkers had higher blood oestrogen levels. Higher levels of oestrogen are associated with breast cancer risk, she noted.

That was in 2007. In 2008, US researchers of the University of Mississippi Medical Centre examined the effects of the green tea antioxidant (epigallocatechin-3-gallate) on breast cancer growth in laboratory mice.

During the study one group of female mice was fed a solution of the antioxidant epigallocatechin-3-gallate (EGCG) in water for five weeks while another group of female mice received regular drinking water. During the second week of the study, researchers injected both groups with breast cancer cells.

At the end of the study, researchers measured tumour size, weight, and density as well as VEGF protein levels, which are associated with tumour growth. The results showed that treatment with the green tea antioxidant decreased tumour size by 66 per cent and weight by 68 per cent compared with the control group. Mice fed the antioxidant also had significantly lower density of small blood vessels within tumours and VEGF protein levels.

Of the latter study head researcher, Jian-Wei Gu concluded that the green tea antioxidant EGCG may work against breast cancer by suppressing blood vessel growth in breast tumours as well as slowing the production and migration of breast cancer cells.

Now in a combined study from China and the US, researchers say that regular consumption of green tea may reduce a woman’s risk of breast cancer by about 12 per cent.

The Shangai study, led by Martha Shrubsole from Vanderbilt School of Medicine in Nashville, adds to the ever-growing body of research supporting the anti-cancer benefits of green tea and its antioxidants.

Writing in the Journal of Nutrition, the researchers report that the ‘modest’ reduction was observed from regular green tea drinkers, compared to non-drinkers, after evaluating the diet of 3454 women with breast cancer and 3474 healthy controls aged between 20 and 74. All of the women were individually interviewed and their green tea drinking habits, including regularity, tea strength, and quantities consumed, were assessed.

At the end of the study, the researchers concluded that regular consumption of green tea was associated with a ‘slightly decreased risk for breast cancer’ of 12 per cent, compared to those who didn’t drink green tea.

It may be a modest risk reduction; however, it still is a risk reduction. Sounds good to me.

In addition to the potential anti-cancer benefits, other 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.

Green tea contains between 30 and 40 per cent of water-extractable antioxidants, 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.

‘Green Tea May Protect Against Breast Cancer’ published online 08/05/07, medicalnewstoday.com/articles

‘Antioxidant in Green Tea May Stop Breast Cancer Growth’ by Jennifer Warner, published online 07/04/08, webmd.com

‘Green tea may protect against breast cancer: Study’ by Stephen Daniells, published online 27/01/09, nutraingredients.com