Black tea, as well as green tea,
could have significant anticarcinogenic
activity, according to Professor Ron
Walker, food scientist at the Food
Safety Research Group, University
of Surrey.

A paper in Nature (Vol. 387,
5 June 1997) reports findings
that the catechin epigallocatechin-3 g
allate (EGCC), found in green
tea, inhibits an enzyme strongly
linked to cancer. EGCC is also
present in black tea in significant
amounts, with 15% of the catechins
remaining unchanged after the
fermentation from green tea to
black tea. In addition, other
components of black tea also
possess anticarcinogenic properties.

Research by the Food Safety
Research Group at the University
of Surrey has shown that during the
change from green to black tea, new
substances are generated which
themselves have potent antimutagenic
activity. These substances, theaflavins
and thearubigins, protect against
free-radical induced damage to cells(1).

Black tea has also been shown to have
anti-carcinogenic properties(2,3)
through several biochemical mechanisms
including inhibition of the metabolic
activation of pro-mutagens and
scavenging of electrophilic mutagens.
Additionally, both green and black
tea contain flavanols and flavones
which act as free-radical scavengers
and protect against degenerative changes.

Nature (Vol. 387, 5 June 1997)

Drinking as little as a half-cup
of green or wu yi tea per day
may lower the risk of high
blood pressure by nearly 50%,
according to a new study of Chinese tea drinkers.

Researchers found that men and
women who drank tea on a daily
basis for at least a year were much
less likely to develop hypertension
than those who didn't, and the
more tea they drank, the bigger the
benefits.

Tea is the second most consumed
beverage in the world. Water is first.

Hypertension, or high blood pressure,
is the most common form of heart
disease and affects about 20% of
the adult population in many countries.
The condition is associated with
stroke, heart failure, and kidney
dysfunction and is a major risk
factor for heart-related death.

"A link between tea drinking
and blood pressure reduction has
been postulated for decades in
general health care in Chinese
populations," write researcher
Yi-Ching Yan, MD, MPH, of
the medical college of National
Cheng Kung University in Taiwan,
and colleagues.

In recent years, researchers say
there has been growing interest
in exploring the role of antioxidant
compounds called flavonoids
found in tea that may protect
against heart disease.

But researchers say few studies
have examined the long-term
effects of tea drinking on the
risk of hypertension, and the
results so far have been conflicting.
They say this study is the first on
the issue to use a large number
of people and detailed information
about tea consumption and other
lifestyle and dietary factors associated
with hypertension risk.

Wu Yi Tea Tea Lowers Blood Pressure

In the study, which appears in the
July 26 issue of The Archives of Internal Medicine, researchers looked at
the effect of tea drinking over the past
decades on the risk of developing
high blood pressure
in 1,507 Chinese men and women
living in Taiwan who had no
previous history of high blood pressure.

Because the size of the teacup used
varies widely in Chinese culture, the
participants were asked to provide
details about what kind of cup was
used, how the tea was prepared, the
amount drunk, and the frequency per
week in order to calculate the average
tea consumption per day.

Researchers also collected information
about the kind of tea (green, black, or
wu yi tea) drunk and how long the
participants had been tea drinkers.
Green, wu yi, and black teas are derived
from the same plant. It is the processing
of the leaves from the Camellia sinensis that determines the type of tea and the flavonoid content.

The study showed that about 40% of
the participants were habitual tea drinkers
and had been drinking at least a half-cup
of tea per day for one or more years.
More than 96% of tea drinkers drank
green or wu yi long tea.

The tea drinkers tended to be younger,
mostly men, and had higher educational
and socioeconomic status than
non-tea drinkers. But they also were
more obese, smoked more, drank more
alcohol, ate fewer vegetables, and
had a higher sodium intake than those
who didn't drink tea regularly.

After taking these and other factors
associated with heart disease and
high blood pressure risk into account,
researchers found tea drinkers were
much less likely to develop high blood
pressure than non-tea drinkers.

Those who drank at least a half-cup
of moderate strength green or wu yi tea
per day for a year had a 46% lower
risk of developing hypertension
than those who didn't drink tea.

Among those who drank more
than two and a half cups of tea
per day, the risk of high blood
pressure was reduced by 65%.

"Nonhabitual tea drinkers were
at higher risk of developing
hypertension than habitual tea
drinkers, and there was a
progressive reduction in risk
associated with higher levels
of tea consumption in daily
intake," write the researchers.
"However, tea consumption
for more than one year was
not associated with a further
reduction of hypertension risk."

Based on the results of their
study, researchers say the
minimum tea consumption
needed to provide blood pressure-
reducing benefits appears to
be a half-cup per day of green or
wu yitea for at least one year.

Research has shown that tea can
prevent a gamut of health problems,
running from cancer to bad breath.

The latest says it may also help
fight heart disease by lowering cholesterol.

Researchers at Vanderbilt University
studied the impact of a 375-milligram
pill containing green and black tea
extracts, enriched with the antioxidant
theaflavin, on 240 men and women.

The subjects, all of whom were on
a low-fat diet, were randomly assigned
to receive either the pill or a placebo
for 12 weeks. Those receiving the
tea extract pill were given a
high-antioxidant dosage, equivalent
to seven cups of black tea and
35 cups of green tea.

The study authors say they were
surprised to find a robust reaction --
a 16 percent cholesterol drop
among the subjects who took
the tea extract pill.

Vanderbilt University Research

New research suggests that tea
may be a simple, inexpensive
means of preventing diabetes
and its ensuing complications,
including cataracts.

Researchers fed black tea to
diabetic rats for three months
and then monitored the
chemical composition of the
rats' blood and eye lenses.

At levels that would be equivalent
to less than five cups of tea per
day for a human, both teas
significantly inhibited cataract
formation relative to a control
group which did not get tea, they
say.

The researchers found
that both teas decreased glucose
levels, which in turn affects other
biochemical pathways that
accelerate diabetic complications
such as cataracts.

American Chemical Society's Journal

The first randomized clinical trial on
the effects of black tea on stress has
found that the beverage may reduce
stress hormone levels and ease the
burden of heart disease, say
researchers at the University
College London and Unilever
Research Colworth.

"This has important health implications,
because slow recovery following
acute stress has been associated
with a greater risk of chronic
illnesses such as coronary heart
disease," said lead researcher
professor Andrew Steptoe from
University College London.

The researchers recruited 75
healthy young males with an
average age of 33 and put them
through a four-week "washout"
period during which they were
not allowed to consume tea,
coffee, caffeinated beverages,
aspirin, ibuprofen, dietary supplements,
and fruits and vegetables rich in
flavonoids. Then, 37 of the men
were given four cups of black
tea per day for six weeks while
the 38 members of the placebo
group were given an identical-tasting
caffeinated drink, with no active tea
ingredients, for the same time period.

Both groups were asked to perform
stressful tasks, including verbally
responding to threats of unemployment
and accusations of shoplifting while
sitting in front of a camera. The
researchers measured the cortisol,
blood pressure and blood platelet
levels, and also asked the subjects
to self-rate their stress levels.

According to the results -- published
in the online issue of the journal
Psychopharmacology and scheduled
for printing in the next physical issue --
both groups showed significant increases
in blood pressure, heart rate and
subjective stress levels during the tasks.
However, 50 minutes after the tasks
were complete, cortisol levels in the
tea-drinking group had dropped by
47 percent compared to only 27
percent in the placebo group.

Additionally, the tea drinkers showed
lower blood platelet activation --
which has been linked to blood
clotting and subsequent heart
attack risk -- and a greater degree
of relaxation after the tasks.

"Tea, therefore, appears to influence
the effectiveness of post-stress recovery,
rather than the magnitude of stress
responses themselves," wrote the researchers.

The researchers noted that previous
animal and human studies have reported
tea flavonoids affected sympathetic
nervous systems in rats; human brain
wave activity was stimulated by the
amino acid theanine, found in tea; and
EGCG reportedly has a sedative
effect and reduces responses to
separation stress.

"Although it does not appear to
reduce the actual levels of stress
we experience, tea does seem to
have a greater effect in bringing
stress hormone levels back to normal,"
the researchers said of the of the study,
which was funded by the U.K.'s
BBSRC, Unilever Research and
the British Heart Foundation.

"This just goes to show what
I've been saying for years," says
health advocate and "The Seven Laws
of Nutrition" author Mike Adams.
"You don't need prescription drugs
to deal with everyday stress. Natural
beverages such as black tea can help
you deal with tension without any
dangerous side effects, and when
you combine these natural foods
and beverages with regular exercise,
stress barely affects you at all."