A Mayo Clinic team led by Drs. Tait Shanafelt and Neil Kay were following up on previous, promising research in laboratories, on animal tissue and then on human cells. They administered capsules containing high doses (400 to 2,000 milligrams each) of epigallocatechin gallate, an antioxidant in green tea, to 33 patients with chronic lymphocytic leukemia (CLL), which a news release described as "the most common subtype of leukemia in the United States."
One-third of participants experienced a reduced lymphocyte count, and the majority of individuals who entered the study with enlarged lymph nodes saw a 50-percent or greater decline in their lymph node size, the release stated.
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 leukemia."
Although blood tests can help diagnose CLL early on, there is no cure for the disease, and treatment requires letting it progress. About half of CLL patients have an aggressive form of it that leads to early death. According to the release, "Researchers hope that EGCG can stabilize CLL for early stage patients or perhaps improve the effectiveness of treatment when combined with other therapies."
A follow-up study to this one is already underway. A video interview with Shanafelt can be seen here.