• China and India share the credit for the discovery of tea almost 5 thousand years ago.
• It was introduced to the West by Turkish traders in the 6th century.
• The tea shrub is a perennial evergreen that grows in many areas of the world in a variety of climates. Growth depends on acidic soil (pH 4-5.6).
• There are 4 major types of tea. The most widely consumed and best known are green (nonfermented) and black(fermented) tea. Red, also known as oolong, and yellow tea, both partially fermented, are less popular.
• There are two main active ingredients in tea: polyphenols and methyxanthines.
• Upon ingestion, polyphenols can be easily detected throughout the human or animal body. It is believed that they exert their actions directly at the tissue and cellular level rather than indirectly through intestinal effects. The benefits associated with polyphenols are generally attributed to their antioxidant activity and their ability to scavenge free radical oxygen.
• The most abundant methyxanthine in tea is caffeine. Caffeine exerts its behavioral and other effects through competitive antagonism at adenosine binding sites. Caffeine levels, produced in humans by ingestion of a few cups of tea are sufficient to antagonize adenosine's nervous stimulation of the vascular system, heart, kidney, and adipose tissue. Serum levels of non-esterified free fatty acids are increased by caffeine, thus suggesting a mechanism by which caffeine can cause heart arrhythmias.

• Cancer- Green tea polyphenols have been shown to protect against chemically induced tumor initiation and promotion and to protect against the progression of benign tumors to malignancy in mice. They have also been shown to be radioprotective against UV-induced carcinogenesis in mice.
• Antimutagenic- Green polyphenols are Antimutagenic and reduce the occurrence of chromosome aberrations during mutagen exposure.
• Atherosclerosis and Hypertension- It is believed that the oxidation of low density lipoprotein(LDL) is critical to the development of atherosclerosis in humans. Tea polyphenols are known to block test tube oxidation of LDL by copper ions. Increased green tea consumption, especially more than 10 cups per day is associated with decreased total serum cholesterol, decreased LDL and increased HDL(high density lipoprotein). In addition, the polyphenols in green tea appear to reduce hypertension in mice, possibly through the sedative action of a brain neurotransmitter.
• Infectious Diseases- The antibacterial activity of tea catechins is particularly useful for the treatment of diarrheal diseases like cholera and typhus. Many viruses are adversely affected by the presence of tea catechins including influenza and even HIV.
• Immune Response Stimulator- A few studies show how green tea polyphenols affect the immune system. One polyphenol appears to stimulate B-cell proliferation in mice.
• Anticariogenic- The polyphenolic compounds may protect teeth from decay by killing bacteria. They may also inhibit the collagenase activity of bacteria that lodge in fluid below the gum line and increase the acid resistance of human tooth enamel.

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