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Tea
and Cardiovascular Protection:
Is Green Tea Superior to Black Tea?
A wealth of studies has shown that both green and
black tea have beneficial effects on the cardiovascular system, in spite
of the fact that their active ingredients are different (catechins in
green tea and theaflavins and thearubigens in black tea). So which kind
of tea offers the most cardiovascular protection?
For a study published in Basic Research in Cardiology
in January 2009, German researchers compared the effects of both kinds of tea on
nitric oxide (NO) production and vasodilation (the widening of the blood
vessels). NO does much to help the heart pump blood through the arteries more
easily. It widens the blood vessels, prevents fatty deposits from accumulating
on blood vessel walls, keeps those walls from thickening and stiffening,
prevents excessive narrowing of the blood vessels and generally increases the
flow of blood.
NO is produced primarily in the endothelium, the lining of
the blood vessels. Unfortunately, this is the same area that becomes damaged by
all of the major perpetrators of heart disease, including high
cholesterol, high blood pressure, lack of exercise, smoking and obesity. When
the endothelium is damaged, it doesn't make enough NO, which causes even more
endothelial damage. Clearly, production of sufficient amounts of NO is crucial
to the proper function and health of the blood vessels and, by extension, the
entire cardiovascular system.
In this study, the researchers used a highly fermented black tea
as well as the various catechins found in green tea. Each was combined with
endothelial cells and aortic rings taken from animals. They found that green
tea’s EGCg (but no other catechins) produced a marked increase in NO production
and vasodilation. Black tea’s theaflavins did just as well as EGCg, and the
thearubigens slightly outperformed both. The researchers concluded that green
and black teas are equally potent stimulators of NO production and vasodilation.
And that’s good news for your cardiovascular system, no matter which type of tea
you prefer. So have another cup of tea – green or black!
Lorenz M, Urban J, Engelhardt U, et al. Green and black tea are equally potent
stimuli of NO production and vasodilation: new insights into tea ingredients
involved. Basic Res Cardiol 2009;104(1):100-10.
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Nadine Taylor, M.S., R.D. presents
GreenTeaLibrary.com, the most
comprehensive collection of scientific information describing the
health benefits of green tea.
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