Botanical Considerations in Reducing Cancer Risk: Green Tea
Camellia sinensis (Green Tea) is rich in catechins which exhibit potent antioxidant action. This group of phenols are responsible for green tea's strong free radical scavenging properties, Clinical trials have demonstrated that green tea consumption equivalent to 250mg catechins/day significantly increased antioxidant status and reduces peroxide values, Catechins may also inhibit the production of inflammatory mediators such as leukotrienes and lipoxygenase; and has been shown to block nitric oxide synthase by inhibiting NF-kB. Inflammatory mediators play a significant role in the proliferation of cancer cells.
Green tea extract (EGCG) has been demonstrated in several in-vitro models to increase DNA repair. Other studies have shown that EGCG induces apoptosis (programmed cancer cell suicide); it downregulates cyclin D1 and cyclin-dependent kinase, pausing cell division and inducing apoptosis. It preserve the activity of the repair gene p21 and apoptotic gene BAX leading to cell cycle arrest. It also activates caspase proteases via oxidation, detaining cells in G1 phase of cell division. Several other studies have demonstrated that EGCG suppresses vascular endothelial growth factor (VEGF) expression associated with tumour growth.
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Ho CK, Choi SW, Siu PM, Benzie IF. Effects of single dose and regular intake of green tea (Camellia sinensis) on DNA damage, DNA repair, and heme oxygenase-1 expression in a randomized controlled human supplementation study. Mol Nutr Food Res. 2014 Jun;58(6):1379-83. doi: 10.1002/mnfr.201300751. Epub 2014 Feb 28. PMID: 24585444.
Nakazato T, Ito K, Miyakawa Y, Kinjo K, Yamada T, Hozumi N, Ikeda Y, Kizaki M. Catechin, a green tea component, rapidly induces apoptosis of myeloid leukemic cells via modulation of reactive oxygen species production in vitro and inhibits tumor growth in vivo. Haematologica. 2005 Mar;90(3):317-25. PMID: 15749663.
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