Whilst increasing attention is now rightly being paid to
the health benefits of white and green teas, the virtues of
the much more familiar, and still much more common, black
tea, should not be neglected. All three are products of
the camellia sinensis plant and as such have many common
attributes, particularly in their anti-oxidant functions;
the difference between them being entirely attributable to
the differing methods by which they are produced.
So-called "herbal teas", by contrast, are drinks made from
infusions of the leaves of a wide variety of other plants.
Although these are often very beneficial to health, they
are not "teas" at all in the strict sense, this term being
restricted to the products of the camellia sinenis plant,
and should be considered separately, probably as a branch
of herbal medicine or therapy.
The fresh, ie unprocessed, leaves of the camellia sinensis
plant are rich in compounds known as polyphenols, and
particularly those of a type known as catechins, which are
powerful anti-oxidants. The problem is that these
compounds are easily destroyed by the processing that the
leaves go through. In the case of black teas the process,
known as fermentation, results in the almost complete
oxidation of the catechins resulting in a dramatic loss of
their anti-oxidant power.
The highly prized white teas, by contrast, are produced by
steaming the very young leaves of the camellia sinensis
plant, protecting them from this damaging oxidation. Green
teas are produced by a similar process of heat treatment,
but the older leaves used are not generally as rich in the
active ant-oxidant compounds. There is yet another
category of teas, known as oolong, which fall somewhere
between the green and black varieties by being partially
oxidised (fermented).
Whilst conventional medicine continues to insist that the
evidence for the health giving benefits of all these teas
remains inconclusive, there is in fact ample evidence of
the anti-oxidant power of these beverages. For example, a
number of respectable studies have concluded that moderate
tea consumption (just a few cups day) may reduce the risk
of heart disease by around a third, in the case of black
tea, and a half in the case of green tea. At least one
research report further suggests that tea consumption may
help reduce the risk of stroke by as much as two-thirds.
Since heart disease and stroke remain two of the biggest
causes of premature death and disability in the affluent
Western world, these findings alone would seem to make the
regular consumption of tea, and green tea in particular, a
worthwhile precaution.
But the benefits don't end there.
Free radical oxidative damage to the lining of the blood
vessels is known to be a factor in the development of
atherosclerosis (hardening of the arteries) another major
cause of life threatening cardiovascular disease. The
consumption of black tea has been shown to have a
protective effect on the cells lining the blood vessels
(the endothelium) and to the extent that this effect is due
to anti-oxidant polyphenols, it appears highly likely that
tests with green tea would produce results at least as good.
Less conclusively, but interestingly, there is also
evidence that the anti-oxidant qualities of the polyphenols
in both green and black tea may have a role in combatting
both cancer and osteoporosis.
In the case of cancer, such effects have been clearly
demonstrated in animals, though the evidence in respect of
humans is less clear cut. But to the extent that cancer is
a disease of degeneration, the onset of which may be
hastened by oxidative damage in cells caused by free
radical activity, the anti-oxidant activity of black and
green tea can only be of potential benefit.
Similarly, there is observational evidence that bone mass
density is positively correlated with tea consumption,
which is therefore protective against osteoporosis,
possibly because of the drink's anti-oxidant properties,
but the causal link is not fully understood.
Despite the familiar reservations of conventional medicine,
there appears good evidence for the anti-oxidant qualities
of the polyphenols in tea in general, and green tea in
particular. But that's not all. Tea is also a good source
of some trace minerals, including manganese, which is
itself a powerful anti-oxidant. Black tea is a
particularly good source, and a convenient way of obtaining
this mineral, which is often drastically under supplied in
food. In addition to its general anti-oxidant properties,
manganese is also known to nutritional therapists as an aid
to cardiac and bone health, in relieving the symptoms of
diabetes, and in treating certain types of seizure.
The only likely downside to the consumption of significant
quantities of tea is that both green and black varieties
may contain considerable amounts of caffeine. Strong black
tea is also rich in tannin, the acidic substance which also
gives the astringent taste to red wines, and which may lead
to minor stomach disturbances if overdone This problem
does not arise with green tea, however, and both black and
green varieties are readily available in decaffeinated
form, the latter also in a range of enhanced natural
flavours for improved palatability.
----------------------------------------------------
Steve Smith is a freelance copywriter specialising in
direct marketing and with a particular interest in health
products.
Find out more at
http://www.sisyphuspublicationsonline.com/LiquidNutrition/In
formation.htm
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