Four case studies indicate consuming green tea may be linked to a dose dependent improvement in leukemia.
Four case reports of leukemia patients who began drinking green tea, reported by doctors at the Mayo Clinic in Rochester, Minnesota, discovered that three of four patients who started drinking green tea or taking green tea extracts experienced an improvement in their condition. After using green tea, the fourth patient also experienced improvement although her disease status remained unchanged according to standard measurements.
The patients all had chronic lymphocytic leukemia (CLL) which usually develops in middle-age or later and typically progresses slowly. All four patients began using green tea after hearing media reports about a cell culture study the Mayo Clinic researchers conducted, which showed that the green tea component epigallocatechin gallate (EGCG) killed cancer cells taken from chronic lympocytic leukemia patients. In the study, EGCG induced apoptosis (or self-destruction) in leukemia cells by interfering with communication signals essential to the cells’ survival.
The Mayo Clinic physicians discovered that three of the subjects showed signs of a regression in their cancer after consuming green tea or green tea capsules. The fourth experienced an improved white blood cell count, though her disease remained unchanged by standard criteria.
In one case, the patient had exhibited progressive swelling in her lymph nodes (a characteristic of CLL) before she started taking green tea capsules twice per day. Over the next year, her lymph nodes steadily decreased in size. Another patient also experienced an improved white blood cell count after she began consuming eight cups of green tea per day.
The researchers who reported the case studies also are conducting an ongoing clinical trial sponsored by the National Cancer Institute to determine whether EGCG extract has a role to play in treating CLL.
Previous studies have indicated that green tea and green tea extracts have anti-cancer abilities, possibly due to the tea's concentration of certain antioxidants. It is thought that EGCG is the most powerful antioxidant contained in green tea.
Shanafelt TD, Lee YK, Call TG, Nowakowski GS, Dingli D, Zent CS, Kay NE. Clinical effects of oral green tea extracts in four patients with low grade B-cell malignancies. Leukemia Research, published online, December 1, 2005.