Green tea may contain substances with powerful medical benefits, according to findings published yesterday.
A study involving a small number of patients suggest that green tea may have therapeutic value against some forms of leukaemia.
Researchers from the Mayo Clinic in Rochester, Minnesota, USA, investigated the active ingredient in green tea called epigallocatechin gallate, or EGCG. EGCG is a type of catechin – antioxidants found in plants. It is already sold in supplement form.
Dr Tait Shanafelt and colleagues tested the safety of EGCG capsules on 33 patients with chronic lymphocytic leukaemia.
Patients were given one of eight different oral doses of Polyphenon E, a compound whose primary active ingredient is EGCG. Doses varied from 400mg to 2,000mg twice a day.
Results showed that patients could tolerate the chemical fairly well at high doses and that lymphocyte (white blood cell) count was reduced in a third of participants. The researchers say that they did not reach a maximum tolerated dose, even at 2,000mg twice a day.
Full results are published on the website of the Journal of Clinical Oncology.
Dr Shanafelt said: "We found not only that patients tolerated the green tea extract at very high doses, but that many of them saw regression to some degree of their chronic lymphocytic leukaemia.
"The majority of individuals who entered the study with enlarged lymph nodes saw a 50 per cent or greater decline in their lymph node size."
The team hope that EGCG can stabilise the disease for early stage patients and improve the effectiveness of treatment when combined with other therapies.
They previously found that EGCG can induce cell death in leukaemic B-cells from patients with chronic lymphocytic leukaemia. They will now test the highest dose on a further group of patients.
Shanafelt, T. et al. The Journal of Clinical Oncology, published online May 27, 2009.
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