By: Alex De Alvarado and Lorenzo Cohen, Ph.D.
Tea is the second most consumed beverage in the world after water. Its origins are in Southeast Asia, where tea has been consumed for thousands of years.
In China, tea has long been part of cultural practices and incorporated within traditional Chinese medicine. Recently, there has been a dramatic increase in scientific research examining the health benefits of green tea, including epidemiological studies, preclinical research and clinical trials.
Of particular interest is the examination of ECGC -- a powerful antioxidant that is thought to be one of the main components of the health benefits of tea.
Several epidemiologic studies in East Asia have found associations between green tea and lower cancer incidence. For example, in 1994 the Journal of the National Cancer Institute published the results of a study indicating that drinking green tea reduced the risk of esophageal cancer in Chinese men and women by nearly 60%.
The research on green tea
In a recent study, MD Anderson researchers examined the effects of green tea extract on people with a precancerous condition called oral leukoplakia. Results were encouraging, showing less progression towards development of cancer in more than half of those who took the extract.
A study presented at the 2010 annual meeting of the American Society of Clinical Oncology showed preliminary evidence that the ECGC component of green tea may reduce the number of leukemia cells in patients with chronic lymphocytic leukemia (CLL). The Mayo Clinic researchers are looking forward to more controlled clinical trials to confirm these benefits as well.
Ask your doctor
Although drinking green tea is generally considered safe, patients with cancer should discuss possible contraindications or side effects with their physician, especially if consuming green tea as a supplement versus as a drink. Green tea contains caffeine, which could have different stimulatory effects on individuals. In addition, green tea may interact with certain anticancer drugs and supplements.
The initial promising research on the benefits of green tea warrants further investigation to conclusively determine its role in the prevention and treatment of cancer. In the meantime, tea will continue to be a source of refreshment, relaxation and ritual.
MD Anderson Resources:
News Release - Green Tea Shows Promise as Chemoprevention Agent for Oral Cancer, M. D. Anderson Study Finds
Integrative Medicine Program
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Reduced risk of esophageal cancer associated with green tea consumption. Gao YT, McLaughlin JK, Blot WJ, Ji BT, Dai Q, Fraumeni JF Jr.J Natl Cancer Inst. 1994 Jun 1;86(11):855-8.
Phase II randomized, placebo-controlled trial of green tea extract in patients with high-risk oral premalignant lesions.Tsao AS, Liu D, Martin J, Tang XM, Lee JJ, El-Naggar AK, Wistuba I, Culotta KS, Mao L, Gillenwater A, Sagesaka YM, Hong WK, Papadimitrakopoulou V.Cancer Prev Res (Phila Pa). 2009 Nov;2(11):931-41.
Phase II trial of daily, oral green tea extract in patients with asymptomatic, Rai stage 0-II chronic lymphocytic leukemia (CLL). T. D. Shanafelt, T. Call, C. S. Zent, B. LaPlant, J. F. Leis, D. Bowen, M. Roos, D. F. Jelinek, C. Erlichman, N. E. Kay J Clin Oncol 28:7s, 2010 (suppl; abstr 6522)
National Cancer Institute Fact Sheet