Tea and extract health
benefit of drinking
July 12 2017 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.
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.
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.
Drinking hibiscus tea could lower blood pressure.
Drinking jasmine tea is popular in Thailand. Using jasmine oil as aromatherapy can enhance mood. This herb has a high polyphenol content.
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
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
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.
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.
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.
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
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%