TEA
TEA FLAVONOIDS MAY PROTECT AGAINST ATHEROSCLEROSIS
Epidemiological studies have reported a reduced risk of
coronary heart disease in subjects with a high flavonoid
intake. The protective effect of flavonoids, in particular
flavonols, has been attributed to antioxidant activity.
Tea is the major dietary source for flavonoids in Western
populations. A study was, therefore, carried out to determine
the association of tea intake with aortic atherosclerosis.
The analysis formed part of the Rotterdam Study, a prospective
study of men and women aged 55 years and older. Dietary
intakes were assessed at baseline by a semiquantitative
food frequency questionnaire. Calcified plaques in the abdominal
aorta were radiographically detected after 2 to 3 years
of follow-up. Multivariable analyses showed a significant,
inverse association of tea intake with severe aortic atherosclerosis.
Odds ratios decreased from 0.54 for drinking 125 to 250
mL (1-2 cups) of tea to 0.31 for drinking more than 500
mL/d (4 cups per day). The associations were stronger in
women than in men. Thus, this study indicates a protective
effect of tea drinking against ischemic heart disease.
Geleijnse, J.M. et al
ARCH. INT. MED. 1999, 159 (18) 2170-4
Researchers at the University of Kansas Lawrence have found
that epigallocatechin gallate (EGCG), an antioxidant found
in green tea, is at last 100 more times more effective than
vitamin C and 25 times more effective than vitamin E at
protecting cells and DNA from damage believed to be linked
to cancer, heart disease and other potentially fatal illnesses.
The antioxidant has twice the antioxidant benefit of resveratrol,
found in red wine. Excessive amounts of EGCG are excreted,
as it is water soluble.
Papers presented at the Second International Scientific
Symposium on Tea and Human Health in Washington DC indicated
that black tea is as high in antioxidants as green tea.
However, the above research indicated that there is less
than half as much EGCG in black and oolong tea as there
is in green tea, because green tea is steamed immediately
after it is picked, which prevents the leaves from oxidizing.
Furthermore, Dr. Yoshimasa Yamamoto of Showa University
in Japan has found that green tea contains catechins that
show strong antibacterial activity against helicobacter,
which is a cause of stomach ulcers.
When EGCG from green tea is added to sulindac, the mixture
was found to be 2-8 times more effective in killing lung
cancer cells than sulindac alone, according to the Japanese
Cancer Association. EGCG was also tested with tamoxifen,
and the compound was twice as effective in killing the cells
than the drug alone. In both cases the combined medication
also reduced the risk of side effects.
Dr. Junshi Chen of the Chinese Academy of Preventive Medicine
in Beijing studied patients who had been diagnosed with
precancerous oral lesiions. One group of patients rinsed
their mouths with the components found in green and black
tea, and Chen painted a mixture of tea and glycerin on the
patients’ lesions. After six months the size of the
lesions had decreased in 38% of the treated group and increased
in 3%, while the lesions in the untreated group decreased
in 10% and increased in 6%.
Tea is a major source of manganese, according to experts
at Britain’s Tea Council, and also contains potassium.
It is one of the few natural sources of fluoride.
Kimron Shapiro, a professor of psychology at the University
of Wales, has found that tea drinking increases concentration
and the ability to learn and to do two jobs at once. The
research demonstrated that caffeine was not responsible
because those drinking tea out-performed those given a caffeine-only
drink.
J. CHINESE MED. January 1999
LOWER RISK OF COLORECTAL AND PANCREATIC CANCERS IN DRINKERS
OF GREEN TEA
In a Chinese study, 931 patients newly diagnosed with cancers
of the colon, rectum or pancreas were questioned about their
lifestyles, medical history and dietary habits, including
tea consumption. When matched with healthy controls the
results showed that men who drank at least one cup per week
of green tea for 6 months or more had a reduced risk of
these cancers compared to those who were not regular tea
drinkers.
INT. J. CANCER 1997, 70, 255-258
Courtesy HERBALGRAM No. 44, p17-18
A CUP A DAY OF GREEN TEA MAY EQUAL OR SURPASS VITAMINS
C & E
A study has shown that green tea (Camellia sinensis) may
provide antioxidant benefits similar to vitamins C and E.
The vitamins reduce the oxidation of low-density lipoprotein
(LDL), or “bad” cholesterol, a process that
can lead to clogged arteries. In tests in Australia green
tea was found to be more active than vitamin C and practically
equivalent to that of vitamin E. The researchers concluded
that if green tea’s antioxidant components are fully
absorbed, a cup a day may be enough to provide an adequate
intake of antioxidants.
Jones, K.
HERBS FOR HEALTH 1997, Nov/Dec 83
