Chapter 47: Green Tea

INTRODUCTION

SOURCE

Derived from Camellia sinensis, an evergreen tree belonging to the Theaceae family (Figure 47-1), green tea has long been a popular beverage worldwide, particularly in Asian countries. Its use by human beings is thought to date back 4,000 years.³ During the last 15 years, it has also gained notable attention because of its purported antioxidant and anticarcinogenic properties. In fact, green tea is one of the most heavily researched of the antioxidants and myriad studies on the cutaneous effects of green tea appear in the literature.⁴ Green tea, rife with plant polyphenols, displays significant antioxidant, chemopreventive, immunomodulatory, and anti-inflammatory activity and affects the biochemical pathways important in cell proliferation, when administered either topically or orally.^2,5,6 For this reason, and because of its widespread popularity as a beverage, green tea polyphenols are among the most frequently studied herbal agents used in medicine.

Polyphenols, many of which are potent antioxidants, are a large, diverse family of thousands of chemical substances found in plants (Table 47-1). The four major polyphenolic catechins found in green tea include: ECG [(-)EpiCatechin-3-O-Gallate], GCG [(-)GalloCatechin-3-O-Gallate], EGC [(-)EpiGalloCatechin], and EGCG [(-)EpiGalloCatechin-3-O-Gallate], the most abundant and biologically active green tea constituent. Like green tea, white tea is derived from C. sinensis, but it is more expensive because it is harder to obtain. White tea actually comes from the tips of the green tea leaves or leaves not yet fully opened, with buds still covered by fine white hair. Of the four primary “true teas,” green and white are unfermented; black tea is fermented; and oolong tea is semi-fermented.^2,7