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Prostate cancer is a leading cause of cancer deaths in the Western world. Phytochemicals in green and black tea may reduce the risk of prostate cancer but their bioavailability remains unclear. The aim of this study was to determine the bioavailability and bioactivity of tea polyphenols and theaflavins. Theaflavins are oligomeric polyphenols synthesized from flavonol units. Previous studies have shown that mainly green tea can reduce the growth prostate carcinoma. The chemopreventive effect of green tea may be attributed to phytochemicals such as epigallocatechin gallate, epicatechin gallate and epigallocatechin.
Mice were fed with a diet supplemented with decaffeinated black tea. The researchers found polyphenols and theaflavins - and their conjugates - in several tissues such as small and large intestine, liver and prostate. The bioavailability of theaflavins was considerably higher than that of epigallocatechin gallate. In another study, mice were fed with green tea for one day after which they received a normal diet. The levels of epigallocatechin gallate, but not epicatechin gallate, remained stable one day after the administration of the green tea. Tests were also conducted on prostate cancer patients. Men who had to undergo a prostatectomy consumed green tea and black tea before the intervention. The researchers found no tea polyphenols in the serum but discovered that the proliferation of isolated prostate cells was less from patients who consumed green. The effect of black tea was less evident. The isolated prostate cells were cultivated in a medium containing serum, which was collected from patients after consumption of green tea and black tea. The inhibition of the growth of the prostate cancer cells may be caused by polyphenol metabolites or growth factors affected by the tea polyphenols.
The study concluded that tea polyphenols and theaflavins are bioavailable in the prostate and may help to prevent prostate cancer.
Source: Henning SM, Aronson W, Niu Y, Conde F, Lee NH, Seeram NP, Lee R-P, Lu J, Harris DM, Moro A, Hong J, Pak-Shan L, Barnard RJ, Ziaee HG, Csathy G, Go VLW, Wang H and Heber D. Tea Polyphenols and Theaflavins Are Present in Prostate Tissue of Humans and Mice after Green and Black Tea Consumption
. Journal of Nutrition. July 2006, 136:1839-1843
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