The tea plant is a large shrub
with evergreen leaves, used medicinally for more than 5000
years in China where it originated. Tea is now the second-most
consumed beverage in the world. Based on the different processes
in tea making, it is categorized as Green Tea, Black Tea,
Oolong Tea, White Tea, Yellow Tea and Dark Tea. A number of
beneficial health effects are attributed to regular consumption
of green tea and dried/powdered extracts of green tea are
available as dietary supplements.
Green tea is prepared by picking, lightly steaming and allowing
the leaves to dry. The active constituents in green tea are
a family of polyphenols (catechins) and flavonols, which possess
potent antioxidant activity. Tannins, large polyphenol molecules,
form the bulk of the active compounds in green tea, comprised
nearly 90%of catechins. Several catechins are present in significant
quantities; epicatechin (EC), epigallocatechin (EGC), epicatechin
gallate (ECG) and epigallocatechin gallate (EGCg). EGCg makes
up about 10-50% of the total catechin content and appears
to be the most powerful of the catechins – with antioxidant
activity about 25-100 times more potent than vitamins C and
E. A cup of green tea may provide 10-40mg of polyphenols and
has antioxidant activity greater than a serving of broccoli,
spinach, carrots or strawberries. A number of commercial green
tea extracts are standardized to total polyphenol content
and/or EGCg content. |
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| Latin Name |
Camellia sinensis L. |
| Common Name |
Tea |
| Plant Family |
Theaceae |
| Part of Plant Used |
Leaf |
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| Molecular Structure of Active Substance |
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| Benefits |
• Anti-atherogenic / Reduces cholesterol &
triglycerides |
• Anti-oxidant/Free radicals scavenging |
• Reduces blood clotting |
• Enhances immune function |
• Enhances weight management |
• Anti-cancer/Anti-Radiation |
• Reduces platelet aggregation |
• Protects against digestive and respiratory
infections |
• Blocks the attachment of the bacteria to the
teeth associated with dental cavities |
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Mechanism
Because the active compounds, the catechins, found
in green tea are known to possess potent antioxidant activity, they
may provide beneficial health effects by protecting the body from
the damaging effects of oxidative damage from free radicals. A number
of chronic disease states have been associated with free radical
induced oxidative damage, including cancer, heart disease, and suppressed
immune function and accelerated aging.
Safety
Adverse or toxic effects of isolated tea catechins
or polyphenols have not been reported in humans. Gastrointestinal
disturbances and central nervous system (CNS) stimulation associated
with high doses of green tea extract have been attributed to their
caffeine content.
Green tea consumption of as much as 20 cups per
day has not been associated with any significant side effects. In
high doses, teas that contain caffeine may lead to restlessness,
insomnia and tachycardia. Decaffeinated versions of green tea and
green tea extracts are available – but due to differences
in caffeine extraction methods, the amounts of phenolic/catechin
compounds can vary between extracts.
It is recommended that consumers select an extract
that is decaffeinated as well as standardized for total polyphenol
content and/or catechin concentrations.
Applications
• Can be delivered in supplement form of a singular
substance or incorporated into healthy formulas
• Easily incorporated into health beverage due
to its high solubility in water
• Can be used as food additives
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Dosage
• Typical dosage recommendations are for 125-500mg/day
– preferably of an extract standardized to at least 60% polyphenols
and/or EGCG as a marker compound (this should
be equivalent to 4-10 cups of brewed green tea).
• Consult physicians if higher dosage is required.
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