Benefits Of Green Tea In Reducing An Important
Risk Factor For Heart
Disease
Science Daily (July 3, 2008) — More evidence for
the beneficial effect of green tea on risk factors for heart disease has
emerged in a new study. The study found that the consumption of green tea
rapidly improves the function of (endothelial) cells lining the circulatory
system; endothelial dysfunction is a key event in the progression of
atherosclerosis.
The study, performed by Dr Nikolaos Alexopoulos and colleagues at the 1st
Cardiology Department, Athens Medical School in Greece, was a randomised
trial involving the diameter measurement (dilatation) of the brachial artery
of healthy volunteers on three separate occasions - after taking green tea,
caffeine, and hot water (for a placebo effect). The measurements were taken
at 30, 90 and 120 minutes after consumption. Dilatation of the brachial
artery as a result of increased blood flow (following a brief period of
ischaemia of the upper limb) is related to endothelial function and is known
to be an independent predictor of cardiovascular risk.1
Results showed that endothelium-dependent brachial artery dilatation
increased significantly after drinking green tea, with a peak increase of
3.9 per cent 30 minutes after consumption. The effect of caffeine
consumption (or hot water) was not significant.
While black tea has been associated with improved short and long-term
endothelial performance, this is the first time that green tea has been
shown to have a short-term beneficial effect on the large arteries. Another
study has already shown that green tea reverses endothelial dysfunction in
smokers.
Green tea, which originates in China but is now consumed throughout the
world, is made with pure leaves, and has undergone little oxidisation during
processing. The cardiovascular benefits of all teas - as well as dark
chocolate and red wine - are attributed to the flavonoids they contain and
their antioxidant activity.2 However, says investigator Dr
Charalambos Vlachopoulos, flavonoids in green tea are probably more potent
antioxidants than in black tea because there has been no oxidisation.
"These findings have important clinical implications," says Dr
Vlachopoulos. "Tea consumption has been associated with reduced
cardiovascular morbidity and mortality in several studies. Green tea is
consumed less in the Western world than black tea, but it could be more
beneficial because of the way it seems to improve endothelial function. In
this same context, recent studies have also shown potent anticarcinogenic
effects of green tea, attributed to its antioxidant properties."
Notes
- The study measured flow-mediated dilatation of the
brachial artery, which is predominantly dependent on the release of nitric
oxide from the endothelium and represents a well accepted estimate of
endothelial function. Measurement of the brachial arteries was performed
by high-resolution ultrasound.
- Flavonoids are naturally found in many plants and
have been shown to have many different biological effects in humans. Their
antioxidant effects have been found in red wine, red grapes and dark
chocolate. Oxidative stress, which has been associated with many human
diseases, can be reversed by antioxidant intake.
Journal reference:
Alexopoulos et al.
The acute effect of green tea consumption on endothelial function in healthy
individuals. European Journal of Cardiovascular Prevention &
Rehabilitation, 2008; 15 (3): 300 DOI:
10.1097/HJR.0b013e3282f4832f
European Society of Cardiology (2008, July 3). Benefits
Of Green Tea In Reducing An Important Risk Factor For Heart Disease.
ScienceDaily. Retrieved July 7, 2008, from http://www.sciencedaily.com
/releases/2008/07/080702080624.htm
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