September 27, 2010
The Anioxidant Power of Green Tea
Polyphenols are potent antioxidant compounds that have demonstrated greater antioxidant protection than vitamin C.
Research suggests that polyphenols provide cancer-protective properties by blocking the formation of cancer-causing compounds, suppressing the activation of carcinogens and effectively detoxifying cancer-causing agents, as well as reducing the inflammation associated with cancer and other diseases.
Numerous studies show that polyphenols reduce the risk of cancers of the gastrointestinal tract, including cancers of the stomach and colon, lungs, prostate and breast. Polyphenols may also improve a woman's prognosis once she's diagnosed with breast cancer by lowering the risk of the cancer coming back by 46 per cent.
How much do I need?
Green tea is a popular source of polyphenols, with health benefits if about three cups daily are consumed (at least 240 to 300 milligrams). To achieve some degree of protection, nutrition and health experts recommend you drink two to three cups a day.
Studies suggest hot, brewed green tea is better than the cold variety as adding ice dilutes the tea. As tea cools, the polyphenols and caffeine may bond and sink to the cup's bottom where you are less likely to consume them.
Instant tea has a very low amount of polyphenols.
Tea also contains 50 to 100 mg of caffeine. Overconsumption may produce nervousness, anxiety, insomnia and irritability. Look for varieties that use water to decaffeinate the leaves rather than a solvent such as ethyl acetate, which lowers antioxidant content up to 70 per cent.
Avoid milk in your tea, as research suggests that it interferes with polyphenol absorption.
On the other hand, adding lemon or other citrus fruits to tea increases the bioavailability of green tea's antioxidants.
Green and white teas require water that is hot but cooler than boiling, since hotter temperatures may affect their flavor. Steep tea for one to three minutes to absorb polyphenols, but not so long that it tastes bitter.
Where do I find it?
Both green tea and black tea come from the same plant. Green tea is produced by lightly steaming the fresh-cut leaf. The color of a tea actually depends on its processing method, particularly on how much oxidation it undergoes during production.
As a rule, the less oxidized a tea, the lighter colour it is and the more antioxidant compounds it contains. Green tea therefore has higher antioxidant levels than black tea.
The major polyphenols in green tea are flavonoids (catechin, epicatechin gallate (EGCG) and proanthocyanidins). When selecting commercial green tea and extracts, look for the highest level of EGCGs and total polyphenol content.
Find varieties with whole tea leaves, as they have more surface area for hot water to extract the flavor and the antioxidants in the leaf. For green tea, look for matcha and sencha varieties, as they tend to have the highest antioxidant values.
Green tea extracts and other food products containing green tea are available, but typically do not have the same health benefits as the beverage.
Do-it-yourself decaf green tea
This will remove nearly 80 per cent of the tea's caffeine, while retaining its flavor and the majority of its polyphenols.
- Steep tea in hot water for about 30 seconds. Since caffeine is water soluble, most of it will be released into the water.
- Discard this liquid and save the tea leaves.
- Add fresh hot water to tea leaves and steep as usual.
Posted by Lisa at September 27, 2010 6:26 AM
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