Tea and Tea Extracts by Ray Sahelian, M.D. Health Benefit of Tea Drinking
It is quite likely that for thousands or tens of thousands of years human beings boiled water and added different herbs and leaves to it and drank this herbal and water concoction we call tea. The recorded history of tea probably began in ancient China thousands of years ago. Tea is second only to water in worldwide consumption of fluids.
What is tea?
Tea comes from "Camellia sinensis", an
evergreen shrub that may grow up to 50 feet in the wild. When cultivated
for harvest the tea bushes are kept to a height of about three feet.
Thousands of varieties of tea are grown each with its own specific
characteristics. Tea could also be considered any herb that is brewed in
water and drank for pleasure or a health benefit.
Types of tea
There are four main types of tea: which are Black, Green, Oolong, and
White. About 80% of what Americans consume is black tea (fermented leaves
of the Camellia sinensis shrub; examples include English breakfast,
Darjeeling and Earl Grey).
Black tea is withered, fully oxidized and dried. Black tea yields a
hearty, amber-colored brew. Some of the popular black teas include English
Breakfast, and Darjeeling.
Green tea. skips the oxidizing step. It is simply withered and then dried.
It has a more delicate taste and is pale green / golden in color. To
purchase
Green-Tea-Extract.
Oolong tea, popular in China, is withered, partially oxidized, and dried.
Oolong is a cross between black and green tea in color and taste.
White tea is the least processed. A very rare tea from China, White tea is
not oxidized or rolled, but simply withered and dried by steaming.
Tea and endothelial cell
function, nitric oxide production, and ACE inhibition
Drinking tea may be good for your arteries.
Dr. Mahmoud Zureik evaluated older women who dranking at least three cups of tea a day. He found women who drink tea have less plaque in their arteries, lowering their risk for heart disease and stroke. The association between fewer instances of carotid plaques and increased daily tea consumption was independent of other dietary habits, major vascular risk factors, age, area of residence, and education. Dr. Mahmoud Zureik says there was no association of tea consumption with carotid plaques in men. The researchers did not look into the types of tea consumed or the duration of tea drinking among participants. Arteriosclerosis, Thrombosis, and Vascular Biology, February 2008.
Tea flavanols inhibit angiotensin-converting enzyme activity and increase
nitric oxide production in human endothelial cells.
J Pharm Pharmacol. 2006 Aug;58(8):1139-44. Department of Medicine
and Care, Division of Pharmacology, Faculty of Health Sciences, Linköping
University, Sweden.
A diversity of pharmacological effects on the cardiovascular system have
been reported for green tea: antioxidative, antiproliferative and anti-angiogenic
activity, and nitric oxide synthase activation. The purpose of this study
was to investigate if the connection between tea and angiotensin-converting
enzyme ACE and nitric oxide might be an explanation of the pharmacological
effects of tea on the cardiovascular system. Cultured endothelial cells
from human umbilical veins were incubated with extracts of Japanese Sencha
(green tea), Indian Assam Broken Orange Pekoe (black tea) and Rooibos tea,
respectively. After incubation with green tea, black tea and Rooibos tea
for 10 min, a significant and dose-dependent inhibition of ACE activity
was seen with the green tea and the black tea. No significant effect on
ACE was seen with the Rooibos tea. After 10-min incubation with (-)-epicatechin,
(-)-epigallocatechin, (-)-epicatechingallate and (-)-epigallocatechingallate,
a dose-dependent inhibition of ACE activity was seen for all four tea
catechins. After 24-h incubation, a significantly increased dose-dependent
effect on NO production was seen for the green tea, the black tea and the
Rooibos tea. After 24-h incubation with (-)-epicatechin, (-)-epigallocatechin,
(-)-epicatechingallate and (-)-epigallocatechingallate, a dose-dependent
increased NO production was seen. In conclusion, tea extracts from C.
sinensis may have the potential to prevent and protect against
cardiovascular disease.
No milk with tea
Drinking tea can reduce the risk of heart disease and stroke but only if
milk is not added to the brew. Tea improves blood flow and the ability of
the arteries to relax but researchers at the Charite Hospital at the
University of Berlin in Mitte found milk eliminates the protective effect
against cardiovascular disease. "The beneficial effects of drinking black
tea are completely prevented by the addition of milk, said Dr. Verena
Stangl, a cardiologist at the hospital. Verenca Stangl and her team
discovered that proteins called caseins in milk decrease the amount of
compounds in tea known as catechins which increase its protection against
heart disease. They believe their findings, which are reported in the
European Heart Journal, could explain why countries such as Britain, where
tea is regularly consumed with milk, have not shown a decreased risk of
heart disease and stroke from drinking tea. The researchers compared the
health effects of drinking boiled water and tea with and without milk on
16 healthy women. Using ultrasound, they measured the function of an
artery in the forearm before and two hours after drinking tea. Black tea
significantly improved blood flow compared to drinking water but adding
milk blunted the effect of the tea. Tests on rats produced similar
results. When rodents were exposed to black tea they produced more nitric
oxide which promotes dilation of blood vessels. But adding milk blocked
the effect. Tea has also been shown to have a protective effect against
cancer so the findings could have further implications.
Green Tea - Drink Green
Tea so you can live longer to drink more green tea
According to a study done with Japanese adults, those who consumed the
most green tea were less likely to die from cardiovascular disease or any
other cause, except cancer, than were the less-frequent green tea
drinkers. Dr. Kuriyama and colleagues analyzed information on 40,530
Japanese adults, 40 to 79 years old, who participated in the Ohsaki
National Health Insurance Cohort Study. The subjects, who were followed an
11 year period from 1995 to 2005, were from a northeastern region of the
country where most of the adults drink green tea three or more times per
day. Adults who drank the most green tea were the least likely to die from
cardiovascular disease. Men who consumed at least five cups of green tea
each day were 12 percent less likely to die from any cause. Whereas, women
who drank five or more cups of green tea each day were 23 percent less
likely to die from any cause and 31 percent less likely to die from
cardiovascular disease.
My thoughts: For the time being, if you don't drink
green tea, it may be a good idea to have a cup a day or a few times a
week. If you already drink green tea on a daily basis, you could perhaps
add another dup a day. It's also possible that drinking a variety of teas
may provide more benefit than just drinking additional green tea. Who's to
say other herbal teas (and there are so many to choose from) are not as
healthy as green tea? Another option is to take a green tea extract
supplement a few times a week. Avoid the use of the tea or the supplement
after mid afternoon since the caffeine and stimulants may interfere with
sleep. One factor to consider is that this study was done in Japan.
Americans have a different diet and lifestyle. Will green tea have similar
benefits in those on a Western diet? Probably, but we can't say for sure.
I know many people who like the taste of green tea, but it is not my
favorite, but I drink a cup a few times a week anyway, particularly when I
visit a Japanese restaurant to have wild Alaskan salmon teriyaki.
Sometimes I bring a small bottle of stevia to the restaurant and add a
couple drops of clear stevia liquid to sweeten the green tea.
Tea for weight loss
Chinese scientists believe tea can help make you thin. They found that the
polyphenol compound in tea -- especially Oolong tea -- can help obese
people battle the bulge. Guo Xirong, director of the Nanjing Institute for
Paediatrics, particularly recommends Oolong tea. Apparently, the
continuous intake of Oolong tea contributes to enhancing the function of
fat metabolism and to controlling obesity.
Tea and Ovarian
Cancer
Woman who drink two or more cups of tea every day may
cut their risk of ovarian cancer in half. Both black and green teas are
rich in antioxidant chemicals called polyphenols, which have been shown to
block cancer growth in lab and animal studies.
Tea and skin cancer
In a study of nearly 2,200 adults, researchers found that tea
drinkers had a lower risk of developing squamous cell or basal cell
carcinoma, the two most common forms of skin cancer. Men and women who had
ever been regular tea drinkers -- having one or more cups a day -- were 20
percent to 30 percent less likely to develop these skin cancers than those
who didn't drink tea. The effect was even stronger among study
participants who had been drinking tea fans for decades, as well as those
who regularly had at least two cups a day. Tea antioxidants may limit the
damage UV radiation inflicts on the skin, according to the study authors,
led by Dr. Judy R. Rees of Dartmouth Medical School in Lebanon, New
Hampshire. In particular, a tea antioxidant known as EGCG has been shown
to reduce burning on UV-exposed skin. It's possible that the antioxidants
in tea are enough to limit skin damage caused by moderate sun exposure,
but not the "more extreme" effects of sun exposure, such as
cancer-promoting damage to the DNA in skin cells. Journal of the American
Academy of Dermatology, May 2007.
Tea substances in prostate gland research
Tea polyphenols and theaflavins are present in prostate tissue of
humans and mice after green and black tea consumption.
J Nutr. 2006 Jul;136(7):1839-43. Department of Pathology, VA West
Los Angeles, CA
Green and black tea have shown promise in the chemoprevention of prostate
cancer. The objective of this study was to determine the bioavailability
and bioactivity of tea polyphenols and theaflavins in human serum and
human and mouse tissues. A decaffeinated black tea diet was administered
to C57BL/6 mice. Tea polyphenols and theaflavins were found in the small
and large intestine, liver, and prostate in conjugated and free forms.
This is the first human study to show that tea polyphenols and theaflavins
are bioavailable in the prostate where they may be active in the
prevention of prostate cancer.
Tea extract for radiation
therapy
Tea extracts applied to the skin promote the repair of damage from
radiation therapy mostly from their ability to attenuate the body signals
that trigger inflammation. According to Dr. Frank Pajonk, from the David
Geffen School of Medicine at UCLA "tea extracts have been used as a folk
remedy for sunburns, which led to their use as a treatment for
radiation-induced skin toxicity. They have proven quite successful in this
regard. In a study reported in the journal BMC Medicine, the researchers
analyzed the effects of green or black tea extracts given to 60 patients
with skin damage related to radiotherapy for head and neck cancers and
cancer in the pelvic region. Treatment with the tea extracts enhanced skin
repair, the report indicates. For radiation damage in the head and neck
region, the green and black tea extracts were comparable in promoting
repair, whereas in the pelvic region, green tea extract was superior.
The tea extracts inhibit a key proteasome, which reduces inflammation. BMC
Medicine, December 1, 2006.
Tea questions
Q. I have heard that green tea helps
people live longer. How many cups of green tea would you recommending
drinking a day?
A. I prefer individuals vary the teas they drink in order to obtain
beneficial substances from a number of herbal teas as opposed to ingesting
the same substances every day. As such, drinking green tea daily or a few
times a week would be quite acceptable, but I would prefer people limit
green tea to no more than 2 cups a day and substitute other herbal teas if
they drink more than 2 cups of tea a day.
Q. Very interesting about milk negating the good
effects of tea. What about coffee? Does it have the artery relaxing
effects with or without milk?
A. It is possible adding dairy to coffee may interfere with some of
the antioxidant or other properties of coffee but I am not sure and will
wait for new research.
Q. I read somewhere about adding honey and
cinnamon to "tea water". Is this just hot water, or is it any flavor of
tea that you add this to?
A. Some people like cinnamon taste in various teas, others don't,
you may wish to try to see which teas you like combined with cinnamon.
Tea and Tea extracts available by raw material suppliers
Black tea Theaflavins 20% ~ 40%;
Green tea catechins 20% ~ 90%;
Green tea polyphenols 20% ~ 98% ;
Green tea L-theanine 20% ~ 35% ;
Green tea caffeine 30% ~ 80% ;
Green tea saponins 50% ~ 70% ;
Green tea EGCG 10% ~ 98%;
Green tea ECG 90%, 95%;
Jasmine tea polyphenols 20% ~ 50%;
Oolong tea polyphenols 20% ~ 90%;
Pu Erh tea polyphenols 30% ~ 50%;
Spearmint tea
information
White tea extract polyphenols 30% ~ 90%