Cancer prevention by tea: animal studies, molecular mechanisms and human relevance

Top Cited Papers
Publisher Website
Google Scholar
Abstract
Tea, made from the dried leaves of the plant Camellia sinensis, is the most popular beverage worldwide after water. Tea and tea polyphenols have been shown to inhibit tumour formation and growth in different animal models for human cancer. The inhibition is associated with decreased cell proliferation, increased apoptosis and suppression of angiogenesis. Tea polyphenols are antioxidants, but they can also generate reactive oxygen species. The major polyphenol from green tea, (−)-epigallocatechin-3-gallate, has been shown to bind directly to several receptors and signalling molecules, and to inhibit the functions of key receptors, kinases, proteinases and other enzymes. Epidemiological studies, however, have not yielded conclusive results on the cancer-preventive effect of tea consumption in humans, possibly owing to different confounding factors. Some human cancer prevention trials with green tea polyphenol preparations have shown promising results. Well-designed epidemiological studies and intervention trials are needed to evaluate the cancer-preventive activities of tea and tea polyphenols in humans. Many issues raised and the experience gained from studies on tea and cancer prevention may be applicable to studies on other dietary constituents.