TABLE OF CONTENTS

Title page-   –         –         –         –         –         –         –         –         –         i

Certification-          –         –         –         –         –         –         –         –         ii

Dedication-  –         –         –         –         –         –         –         –         –         iii

Acknowledgement-         –         –         –         –         –         –         –         iv

Table of contents-  —       –         –         –         –         –         –         –         v

CHAPTER ONE: INTRODUCTION–       –         –         –         –         1

CHAPTER TWO: HISTORY OF GREEN TEA

2.1     History of Green Tea       –         –         –         –         –         –         5

2.2     Preparation of Green tea- –         –         –         –         –         –         7

2.3     Production of Green Tea  –         –         –         –         –         –         8

2.4     Composition of Green Tea-       –         –         –         –         –         10

CHAPTER THREE: HEALTH BENEFIT OF GREEN TEA

3.1     Health Benefits of Green Tea    –         –         –         –         –         14

3.2     Anti- carcinogenic properties-   –         –         –         –         –         15

3.3     Green Tea for skin treatment-    –         –         –         –         –         18

3.4     Anti- fungal activities-     –         –         –         –         –         –         19

3.5     Cholesterol Reduction-    –         –         –         –         –         –         20

3.6     Increase Drug metabolizing enzymes- –         –         –         –         22

3.7     Antioxidant Activities-     –         –         –         –         –         –         22

3.8     Adverse Effects of Green Tea-   –         –         –         –         –         24

CHAPTER FOUR: SUMMARY AND CONCLUSION

4.1     Summary –   –         –         –         –         –         –         –         –         28

4.2     Conclusion- –         –         –         –         –         –         –         –         29

References

CHAPTER ONE: INTRODUCTION

Tea is one of the most widely consumed beverage in the world, next only to water (Cheng, et al., 2004) and well ahead of coffee, beer, wine, and carbonated soft drinks (Rietveld et al., 2003). Tea can be categorized into tree types, depending on the level of fermentation, i.e. green (unfermented), oolong (partial fermented) and black (fermented) tea. The tea fermentation is often used incorrectly in tea processing. The more correct term should be oxidation which mean exposure to air while drying without any additives during the process.

Another form of tea is white tea, which is made from new growth buds and young leaves that have been steamed to inactive polyphenol oxidation and then dried. The buds maybe shielded from sunlight to prevent formation of chlorophyII. Of the 2.5 million metric tons of dried tea manufactured, only 20% is green tea and less than 2% is oolong tea (Pastore et al., 2006).

Green tea is consumed as a popular beverage world-wide particularly in Asian countries like China, Korea, and Japan. There is hardly any other food or drink reported to have as many health benefits as green tea. The ancient Chinese proverb “Better to be deprived of food for three days than tea for one”. Indicate the importance of tea in day-to-day life of Chinese. The Chinese have known about the benefit of green tea since ancient times, using it to treat anything from headache to depression. In her book (green tea; the natural secrete of healthier life” (Taylor, 2007), stated that green tea has been used as medicine in China for at least 4000years.

The chemical composition of green tea varies with climate season, horticultural practices and position of the leaves of the harvested shoot. The major components of interest are the polyphenols. The major polyphenols in green tea are flavonoids. The four major flavonoids in green tea are catechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG) and epigallocatechin gallate (EGCG). Epigallocatechin gallate is viewed as the most significant active compound. The leaves are the richest in EGCG. The usual concentration of total polyphenols in dried green tea leaves is 8-12% (Graham et al., 2001).

Other compound of interest in dried green tea leaves include garthic acid, quercetin, kaempferol, myricetin, caffeic acid, and chlorogenic acid (Katiyar, et al., 2001).

The health-promoting effect of green tea are mainly attributed to its polyphenol content (Naghma et al., 2007), particularly flavones which represent 30% of fresh leaf dry weight (Blumberg et al., 2002). Recently, many of the aforementioned beneficial effect of green tea were attributed to its abundant catechin, (-) –epigallocatechin-3-gallate (EGCG) (Higdon, et al., 2003). Green tea extract are more stable than pure epigallocatechin gallate, one of the major constituent of green tea, are because of other antioxidant constituent of the extract (Hoshina et al., 2001).

In general, herbal medicines are complex mixture of different compound that often act in synergistic fashion to exert their beneficial effect (Raederstorff et al., 2003). However, relatively few herbal medicine have been well characterized and their efficacy demonstrated in systematic clinical treats as compared to western drugs. This review article highlights the recent research on the efficacy, action mechanism and side effects of green tea and its medicine in vitro, in vivo, and ex vivo systems (Xiang et al., 2008).