Tea health
benefit of drinking tea
July 12 2018
by
Ray Sahelian, M.D.
It is 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.
Benefit of tea
J Sci Food Agric. 2017. The synergistic potential of various
teas, herbs and therapeutic drugs in health improvement: A review. Tea
is classified as Camellia sinensis and non-Camellia sinensis (herbal
teas). The common compounds found mainly in green teas are flavan-3-ols
(catechins) (also called flavanols), proanthocyanidins (tannins) and
flavonols. Black tea contains theaflavins and thearubigins and white tea
contains L-theanine and gamma-aminobutyric acid (GABA), while herbal
teas contain diverse polyphenols. Phytochemicals in tea exhibit
anti-microbial, anti-diabetic and anti-cancer activities that are
perceived to be helpful in managing chronic diseases linked to
lifestyle.
Risk, danger, harm
Despite it being a natural product, too much tea in a diet
carries the risk of excessive caffeine intake and other stimulants which
may be of detrimental consequences for some groups of consumers,
particularly in causing shallow sleep or full blown insomnia.
There have been some articles which mention that tea, such as black or green tea, has a high concentration of fluoride and could be harmful if drank too much. I am still awaiting results of more studies to determine whether drinking too much tea can be harmful in terms of this fluoride mineral toxicity.
Teabags not necessary
You can make your own delicious teat by using about a quarter of a
teaspoon of various herbs in your cup and adding hot water. Try
cardamom, coriander, nutmeg, and fennel powder. You can sweeten the
herbal powders by using stevia.
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. The four primary
polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG),
epigallocatechin, epicatechin gallate, and epicatechin.
L-Theanine is a unique non-protein amino acid that is naturally found in tea plants. It contributes to the umami taste and unique flavor to green tea infusion, and thus its content in tea leaves highly impacts the tea quality and price. In addition to the graceful taste, it has been proved to have many beneficial physiological effects, especially promoting relaxation and improving concentration and learning ability.
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.
Appl Physiol Nutr Metab. February 2014. Effect of black tea consumption
on brachial artery flow-mediated dilation and ischaemia-reperfusion in
humans. In a randomized, crossover study, 20 healthy subjects underwent
7 days of tea consumption (3 cups per day) or abstinence from tea. We
examined brachial artery (BA) endothelial function via flow-mediated
dilation (FMD), using high resolution echo-Doppler, before and 90 min
after tea or hot water consumption. Tea consumption resulted in an
immediate increase in FMD whilst no such change occurred after ingestion
of hot water.
Drinking multiple cups of black tea -- as opposed to
green or other tea -- with or without milk is linked to lower odds of a
bone break in older women, American Society for Bone and Mineral
Research 2015 Annual Meeting, Seattle.
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.
Oolong tea, popular in China, is withered, partially oxidized, and dried.
Oolong is a cross between black and green 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.
Q. Would you please
discuss the health benefits of white tea, often called Peony White Tea?
I've read advertising that it is supposed to have three times more
antioxidants than green tea, and less caffeine than green tea, but have
not seen any research on this.
A. I have not seen specific studies with white tea consumption in
humans in terms of their overall health benefit and comparison to other
forms of tea. My general advice is to have half a dozen or a dozen
different types of tea in the kitchen and alternate their use. Each type
of tea has its merits.
Hibiscus
Drinking hibiscus
tea could lower blood pressure.
Jasmine
Drinking jasmine tea is popular in Thailand. Using
jasmine oil as
aromatherapy can enhance mood. This herb has a high polyphenol
content.
Tulsi
Organic India, Tulsi Holy Basil Tea, Sweet Rose, Caffeine Free,
18 Infusion Bags, 1.01 oz (28.8 g)
Tea and mental health, body health
Many studies indicate regular tea
consumption is associated with lower risks of
cognitive
impairment and decline.
Crit Rev Food Sci Nutr. 2014. Epidemiological evidence linking tea consumption to human health: a review. Tea has been widely consumed around the world for thousands of years and drinking tea is a daily habit for people of all ages. Tea is a major source of flavonoids, which have become well known as antioxidants. Tea also contains caffeine and theanine, which have been found to associate with health benefits. Many animal and epidemiological studies have been conducted to investigate the link between tea consumption and human health. However, common questions that arise about tea consumption include: whether all teas are the same, why drinking tea is linked with health benefits, how do the different ways of tea preparation impact on availability of tea components, how much and how long a person should consume tea to obtain health benefits, and whether there is any negative health effect associated with drinking tea.
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. 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.
Hot tea and esophageal
cancer
Reza Malekzadeh of Tehran University of Medical Sciences claims drinking
very hot tea at a temperature greater than 70 degrees Celsius is linked
to a several-fold increased risk of throat cancer compared to sipping
warm or lukewarm tea at less than 65 degrees. Reza Malekzadeh evaluated
the tea-drinking habits of people with esophageal cancer and healthy men
and women from the same area in Golestan Province in northern Iran. That
region has one of the highest rates of throat cancer in the world but
smoking rates and alcohol consumption are low. Nearly all the study
subjects drank black tea regularly, consuming on average more than a
liter each day. People who regularly drank tea less than two minutes
after pouring were several times more likely to develop the esophageal
cancer compared to those who waited four or more minutes. British people
prefer their tea at an average temperature of 56 degrees to 60 degrees.
Tepeated thermal injury to the lining of the throat may make it more
likely for cancer cells to develop.
Lower stroke risk
Drinking tea regularly lowers risk of stroke. In a study of the tea
drinking habits of 838 Chinese men and women, Dr. Andy H. Lee, of Curtin
University of Technology in Perth, Australia, discovered that those who
drank at least one cup of tea, oolong or green, per week for more than
30 years had a 60 percent lower risk of ischemic stroke. Those who drank
more than 2 cups of tea daily had about a 40 percent lower risk of such
strokes, and the risks were even lower in those who drank 2 cups daily.
The researchers also took into account gender, body mass, level of
education, lifelong physical activity, smoking and alcohol intake, the
presence of high blood pressure, cholesterol level, diabetes, and weekly
dietary intake. Stroke, July 2009.
Curr Pharm Biotechnol. 2014. Tea consumption and risk
of ischemic stroke: a brief review of the literature. Stroke is an
important cerebrovascular disease which causes chronic disability and
death in patients. Despite of its high morbidity and mortality, there
are limited available effective neuroprotective agents for stroke. In
recent years, the research aimed at finding novel neuroprotective agents
from natural origins has been intensified. Camellia sinensis tea is the
second most consumed beverage worldwide, after water. It is classified
into green and white, oolong, black and red, and Pu-erh tea based on the
manufacturing process. Catechins are the main phytochemical constituents
of Camellia sinensis which are known for their high antioxidant
capacity. On other hand, it is well known that oxidative stress plays an
important role in the initiation and progression of different
cardiovascular diseases such as stroke. Therefore, the present article
is aimed to review scientific studies that show the protective effects
of tea consumption against ischemic stroke.
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.
Thank you very much for all the great work you
are doing, and sharing with all of us! Quick question – your website
tells us that "The beneficial effects of drinking black tea are
completely prevented by the addition of milk”.I don’t like the tartness
of tea, and always add about ½ teaspoon or so of milk. Instead of milk,
could I use other ‘white liquids’ such as rice, soy, almond milk? Or do
they too interfere with the good properties of tea? The study seems to
think it is only casein that is a problem. Secondly, I read on a website
that one should be concerned about fluoride present in tea leaves. I
drink about 4 to 6 cups of various kinds tea a day, herb, black and
green. Most of it is organic. Should I be concerned? Perhaps you could
add your answers to your website, I am sure others would be interested
in this too.
This is a good question. I suspect the benefits of tea should
remain with the addition of rice, soy or almond milk but I am not sure.
I am not concerned about fluoride in tea leaves. If we were to worried
about every little possible contamination or pollutant in our food and
herbs we could never lead a calm life. There are some minor things and
imperfections in the things we consume that are not worth being
concerned about.
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.
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. 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.
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.
Liang Cha tea in China
Sales of Liang Cha tea keep increasing in China. Liang Cha is renowned in
China for its reputed ability to remove the "spiritual heat and dampness"
from the body, and promote a healthy balance of "basic elements and
fluids." Liang Cha tea includes a great variety, such as Wanghutang Liang
Cha, Health Liang Cha, The King of Chrysanthemum Scented Tea, Liang Cha
tea, and others.
Questions
Q. I have heard that green tea helps
people live longer. How many cups would you recommending
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.
Q. I have read and seen it written a number of
times on various websites that milk can almost completely inhibit the
uptake of the various antioxidants in cocoa and also tea. Apparently the
milk proteins combine with the antioxidants to prevent their absorption.
I'm sure the majority of people tend to drink cocoa made with the addition
of milk, and certainly here in the UK tea is also drunk mainly with milk.
I wonder about your opinion on this and whether it might be important to
stress that milk should be avoided in order to enhance absorption.
A. Yes, there was one recent study that indicated consuming tea
with milk reduced the benefits from some of the antioxidants in the tea.
It may be a good idea to drink herbal teas without milk until further
research confirms or negates the early reports. Or, another approach is to
just enjoy the tea with the milk and get antioxidants at a different time
of day from different supplements, foods and drinks rather than relying on
tea. If you really enjoy tea and coffee with cream or milk, don't deny
yourself the pleasure. I just read this in your newsletter. Since I
am a life long tea with milk drinker, I was very upset about the studies.
Q. Milk or cream with tea and coffee: I think I have solved this with
drinking tea with plain, unsweetened soy milk, which is casein free. I use
stevia to sweeten the tea. Just wanted to share this since I know how
upsetting it can be to have to change an old habit.
I am a big fan of various herbal teas, such as
green tea, rooibos and licorice. I do know that licorice should be
taken in small doses, because of possible fluid retention and
hypertension. I am newly diagnosed with hypothyroidism and tend toward
having anxiety and pms symptoms. I have not gotten the right dosage of
medication yet, and while I am getting there am desperate to find
anything that will help my moods. I have found that rooibos is very
relaxing.
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 ECG 90%, 95%;
Moringa tea
and plant, herbal extract
Oolong tea polyphenols 20% ~ 90%;
Pu Erh tea polyphenols 30% ~ 50%;
Spearmint tea
information
White tea extract polyphenols 30% ~ 90%