Tea
has been cultivated for centuries and remains one of the most widely
consumed beverages in the world. Sipping a cup of green tea can offer
much more than refreshment: the positive health benefits are impressive
and well-documented. The delicate leaves of green tea are packed with
cell-protecting polyphenol phytochemicals called catechins that have
significant medicinal and antioxidant properties. They have been shown
to protect against heart disease, cancer, cell damage from oxidative
stress as well as promote brain health.
Anti-Cancer Effects
Eipgallocatechin gallate,
or EGCG, is a potent polyphenol catechin in green tea that has been the
most extensively studied and shown to have the greatest anti-cancer effects.
In addition to helping prevent cancer, studies have shown that EGCG
also inhibits cancer cell growth by preventing one cancer cell from
splitting into two cells and inhibiting the mechanism that spreads
cancers cells. It also repairs the UVB-induced DNA damage in skin cancer.
EGCG and Your Heart
EGCG also has the highest number of anti-oxidant properties with beneficial effects on the prevention of cardiovascular disease.
These protective benefits for heart disease come from the plant
compound's ability to improve blood flow, lower cholesterol and blood
pressure, and protect against the oxidation of LDL particles that can
lead to atherosclerosis. A study of
40,530 people in Japan, where green tea is most widely consumed, found
that drinking green tea lowered the risk of mortality from
cardiovascular disease by 31 percent in women and 22 percent in men.
What's Good for Your Heart is Good for Your Brain
EGCG in green tea has been shown to protect brain cells and have neuroprotective agents that protect against neurodegenerative disorders such
as Parkinson's and Alzheimer's. The studies show that EGCG can be
protect against the formation of beta-amyloid plaques that are thought
to contribute to Alzheimer's. Studies have also shown that it potentially helps to improve working memory.
The nutrition
guidelines for the Dr. Dean Ornish Program for Reversing Heart Disease
suggest avoiding caffeine; however, green tea is an exception due to the
significant well-studied benefits on health and heart disease. The
nutrition guidelines recommend limiting green tea to 2 cups a day since
it still does contain caffeine, which is a stimulant. Green tea,
however, does have a calming effect that counteracts the high and
jitteriness caused by caffeine because of its concentration of an amino
acid called L-theanine. L-theanine boosts alpha wave activity in the
brain that produces a state of relaxed concentration. A meta-analysis of 13 randomized control studies found that this relaxation effect also decreases blood pressure.
Caffeinated V. Decaffeinated
A
cup of green tea has anywhere from 20-45 milligrams of caffeine, which
is lower than black tea or coffee, which averages 145 to 200 milligrams
per cup. Decaffeinated green tea has less caffeine, but the process to
remove the caffeine also strips it of the beneficial polyphenols. If you
do choose green tea that has been decaffeinated, select a brand that
uses an "effervescence" method, which is a natural process using water
and carbon dioxide without chemicals that preserves most of the
polyphenols present in regular green tea. To derive the most benefit,
drink freshly brewed green tea and avoid powdered tea, sweetened or
bottled, which contain fewer polyphenols.
The Most Benefits
The
concentration of theanine, EGCG and other elements are most abundant in
fresh, high quality loose leaf green tea. The concentration can vary
depending on the brand. Steeping tea in hot water for three to five
minutes will most effectively extract the powerful polyphenol activity
of EGCG.
What effect have you noticed when you replace your daily coffee with green tea?
This article was originally published at Ornish Living.
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