There have been more than 1000 studies done on the antioxidants found in green tea, demonstrating how they may be providing some level of chemoprevention in prostate and breast cancer. Green tea has also been shown to help reduce cardiovascular disease.
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Green tea reduces prostate cancer
The American Cancer Society estimated that about 218,890 new cases of prostate cancer were diagnosed in the United States during 2007. About 1 man in 6 will be diagnosed with prostate cancer during his lifetime. 1
A recent study published in Cancer Prevention Research found that epigallocatechin-3-gallate (EGCg)—the extract that has the highest antioxidant activity of all the green tea catechins—appears to slow down the progression of prostate cancer.
For 34 days researchers at Louisiana State University gave daily doses of 3200 mg. of green tea extract to 26 men, aged 41 to 72 years, who had been diagnosed with prostate cancer and who were scheduled for radical prostate surgery.
This study found a significant reduction in levels of HGF (hepatocyte growth factor, associated with tumor growth), VEGF (vascular endothelial growth factor) and PSA (prostate specific antigen) in men with prostate cancer, with some patients demonstrating reductions of more than 30%.2
The results of this study suggest that further research should be done into the effects of green tea extract in relation to its ability to prevent prostate cancer and to control its progression in men who have already been diagnosed with the disease.
Green tea offers hope for patients with chronic lymphocytic leukemia (CLL)
A study just published in the Journal of Clinical Oncology (August 10, ‘09) tested green tea extract on patients with CLL—the most common form of leukemia, which is usually found in adults over 55 years of age. In the Mayo Clinic study researchers tested EGCg supplements on 33 patients with early-stage CLL and no symptoms. The doses ranged from 400 to 2000 mg taken twice a day.
Fifteen patients showed a 20% or greater reduction in their white blood cell counts, which lasted for at least two months in 11 patients.
Twelve patients had swollen lymph nodes when they were enrolled in the study, and 11 of them had a reduction of at least 50% in the swelling after taking EGCg.
The highest dose seemed to be most effective, with 16 (76 %) of the 21 patients taking 1200 to 2000 mg. of green tea extract showing a response, compared to two (17%) of 12 patients taking 400 to 1000 mg.
The findings suggest that giving green tea extract to early-stage CLL patients could help stabilize the disease.3
Should you take a green tea extract supplement or drink green tea?
Good question. One cup of green tea provides between 20-35 mg of EGCg—the beneficial tea extract. The patients in the Louisiana prostate study took four 800-mg. doses of green tea extract each day, which comes out to 3200 mg. per day.2 The patients in the Mayo Clinic CLL study took up to 4000 mg.of EGCg a day.3
You’d have to drink between 160 and 200 cups a day to obtain that much EGCg! It’s obvious: save your kidneys and bladder by taking a green tea extract supplement.
References
- McLarty J, Bigelow RL, Smith M, Elmajian D, Ankem M, Cardelli JA Tea polyphenols decrease serum levels of prostate-specific antigen, hepatocyte growth factor, and vascular endothelial growth factor in prostate cancer patients and inhibit production of hepatocyte growth factor and vascular endothelial growth factor in vitro. Cancer Prev Res (Phila Pa). 2009 Jul;2(7):673-82. Epub 2009 Jun 19.
- American Cancer Society Detailed Guide: What are the Statistcs About Prostate Cancer?”
- Shanafelt, T., et al. Phase I Trial of Daily Oral Polyphenon E in Patients With Asymptomatic Rai Stage 0 to II Chronic Lymphocytic LeukemiaJournal of Clinical Oncology, Vol 27, No 23 (August 10), 2009: pp. 3808-3814 © 2009.