I try to drink 4 cups of strong white tea daily (with a little orange juice.) Here's why:
Update:
Citric Juice In Tea : The Good and Bad News
Health Benefits of White and Green Tea Consumption
White Tea vs. Green Tea
When discussing white tea vs green tea, it is important to realize that they both come from the same plant, the tea plant Camellia sinensis. The main difference between the two types of tea is that the white tea leaves are harvested at a younger age than the green tea leaves. They both undergo very little processing. White tea is not fermented at all, while green tea is partly fermented. By contrast, black tea is fully fermented. Because they are so gently treated, white tea and green tea retain their content of beneficial antioxidants.
Antioxidants
However, studies have shown that the young, white tea leaves retain antioxidants in higher concentrations than green tea does. Studies have shown that white tea has a concentration of antioxidants that is three times higher than in green tea. Essentially, white tea contains the same concentrations of antioxidants as the young and fresh tea leaf buds that are still attached to the bush. This makes white tea the tea with the highest antioxidant content, which for many is the main reason for drinking white tea. For comparison, one cup of white tea contains approximately twelve (12) times as much antioxidants as fresh orange juice.
Caffeine
White tea contains less caffeine than green tea, about 15 mg per serving compared to the 20 mg for green tea. If caffeine tends to make you jittery, white tea may be the better choice.
Benefits
In general, any benefit attributed to green tea is probably even stronger in white tea.
White Tea Beats Green Tea In Fighting Germs
New studies conducted at Pace University have indicated that White Tea Extract (WTE) may have prophylactic applications in retarding growth of bacteria that cause Staphylococcus infections, Streptococcus infections, pneumonia and dental caries. Researchers presented their findings May 25, 2004 at the 104th General Meeting of the American Society for Microbiology.
"Past studies have shown that green tea stimulates the immune system to fight disease," says Milton Schiffenbauer, Ph.D., a microbiologist and professor in the Department of Biology at Pace University's Dyson College of Arts & Sciences and primary author of the research. "Our research shows White Tea Extract can actually destroy in vitro the organisms that cause disease. Study after study with tea extract proves that it has many healing properties. This is not an old wives tale, it's a fact."
White tea was more effective than green tea at inactivating bacterial viruses. Results obtained with the bacterial virus, a model system; suggest that WTE may have an anti-viral effect on human pathogenic viruses. The addition of White Tea Extract to various toothpastes enhanced the anti-microbial effect of these oral agents.
Studies have also indicated that WTE has an anti-fungal effect on Penicillium chrysogenum and Saccharomyces cerevisiae. In the presence of WTE, Penicillium spores and Saccharomyces cerevisiae yeast cells were totally inactivated. It is suggested that WTE may have an anti-fungal effect on pathogenic fungi.
Several findings in the new study are of particular interest:
* The anti-viral and anti-bacterial effect of white tea (Stash and Templar brands) is greater than that of green tea.
* The anti-viral and anti-bacterial effect of several toothpastes including Aim, Aquafresh, Colgate, Crest and Orajel was enhanced by the addition of white tea extract.
* White tea extract exhibited an anti-fungal effect on both Penicillium chrysogenum and Saccharomyces cerevisiae.
• White tea extract may have application in the inactivation of pathogenic human microbes, i.e., bacteria, viruses, and fungi.
White Tea Helps Weight Loss
Possible anti-obesity effects of white tea have been demonstrated in a series of experiments on human fat cells (adipocytes). Researchers writing in BioMed Central's open access journal Nutrition and Metabolism have shown that an extract of the herbal brew effectively inhibits the generation of new adipocytes and stimulates fat mobilization from mature fat cells.
Marc Winnefeld led a team of researchers from Beiersdorf AG, Germany, who studied the biological effects of an extract of white tea – the least processed version of the tea plant Camellia sinensis. He said, "In the industrialized countries, the rising incidence of obesity-associated disorders including cardiovascular diseases and diabetes constitutes a growing problem. We've shown that white tea may be an ideal natural source of slimming substances".
After treating lab-cultured human pre-adipocytes with the tea extract, the authors found that fat incorporation during the genesis of new adipocytes was reduced. According to Winnefeld, "The extract solution induced a decrease in the expression of genes associated with the growth of new fat cells, while also prompting existing adipocytes to break down the fat they contain".
White tea is made from the buds and first leaves of the plant used to make green tea and the black tea most commonly drunk in Western countries. It is less processed than the other teas and contains more of the ingredients thought to be active on human cells, such as methylxanthines (like caffeine) and epigallocatechin-3-gallate (EGCG) – which the authors believe to be responsible for many of the anti-adipogenic effects demonstrated in their study.
Article: White Tea extract induces lipolytic activity and inhibits adipogenesis in human subcutaneous (pre)-adipocytes _Jörn Söhle, Anja Knott, Ursula Holtzmann, Ralf Siegner, Elke Grönniger, Andreas Schepky, Stefan Gallinat, Horst Wenck, Franz Stäb and Marc Winnefeld _Nutrition & Metabolism article available at the journal website: http://www.nutritionandmetabolism.com/
Citrus Juice, Vitamin C Give Staying Power to Green Tea Antioxidants
To get more out of your next cup of tea, just add juice.
A study found that citrus juices enable more of green tea's unique antioxidants to remain after simulated digestion, making the pairing even healthier than previously thought.
The study compared the effect of various beverage additives on catechins, naturally occurring antioxidants found in tea. Results suggest that complementing green tea with either citrus juices or vitamin C likely increases the amount of catechins available for the body to absorb.
Catechins (pronounced KA'-teh-kins), display health-promoting qualities and may be responsible for some of green tea's reported health benefits, like reduced risk of cancer, heart attack and stroke. The problem, Ferruzzi said, is that catechins are relatively unstable in non-acidic environments, such as the intestines, and less than 20 percent of the total remains after digestion.
"Off the bat you are eliminating a large majority of the catechins from plain green tea," Ferruzzi said. "We have to address this fact if we want to improve bodily absorption."
Ferruzzi tested juices, creamers and other additives that are either commonly added to fresh-brewed tea or used to make ready-to-drink tea products by putting them through a model simulating gastric and small-intestinal digestion. Citrus juice increased recovered catechin levels by more than five times, the study found. Ascorbic acid, or vitamin C, used to increase shelf life in ready-to-drink products, increased recovered levels of the two most abundant catechins by sixfold and 13-fold, respectively.
Lemons and tea go even better together than their popularity might suggest. Lemon juice caused 80 percent of tea's catechins to remain, the study found. Following lemon, in terms of stabilizing power, were orange, lime and grapefruit juices. Ferruzzi said both vitamin C and citrus juices must interact with catechins to prevent their degradation in the intestines, although data made it clear that citrus juices have stabilizing effects beyond what would be predicted solely based on their vitamin C content.
"If you want more out of your green tea, add some citrus juice to your cup after brewing or pick a ready-to-drink product formulated with ascorbic acid," Ferruzzi said.
Ready-to-drink green tea products should optimally contain 100-200 mg of catechins, but oftentimes do not have sufficient levels of tea extract since some people do not like green tea's flavor, Ferruzzi said.
Milk eliminates cardiovascular health benefits of tea
Research published in the European Heart Journal has found that the protective effect that tea has on the cardiovascular system is totally wiped out by adding milk.
Tests on volunteers showed that black tea significantly improves the ability of the arteries to relax and expand, but adding milk completely blunts the effect. Supporting tests on rat aortas (aortic rings) and endothelial (lining) cells showed that tea relaxed the aortic rings by producing nitric oxide, which promotes dilation of blood vessels. But, again, adding milk blocked the effect.
The findings, by cardiologists and scientists from the Charité Hospital, Universitätsmedizin-Berlin, Germany, are bad news for tea-drinking nations like the British, who normally add milk to their beverage. The results have led the researchers to suggest that tea drinkers who customarily add milk should consider omitting it some of the time.
Their study showed that the culprit in milk is a group of proteins called caseins, which they found interacted with the tea to decrease the concentration of catechins in the beverage. Catechins are the flavonoids in tea that mainly contribute to its protection against cardiovascular disease.
Senior researcher Dr Verena Stangl, Professor of Cardiology (Molecular Atherosclerosis) at the hospital, said: “There is a broad body of evidence from experimental and clinical studies indicating that tea exerts antioxidative, anti-inflammatory and vasodilating effects, thereby protecting against cardiovascular diseases. As worldwide tea consumption is second only to that of water, its beneficial effects represent an important public health issue. But, up to now, it’s not been known whether adding milk to tea, as widely practised in the UK and some other countries, influences these protective properties. So, we decided to investigate the effects of tea, with and without milk, on endothelial function, because that is a sensitive indicator of what is happening to blood vessels.”
Sixteen healthy postmenopausal women drank either half a litre of freshly brewed black tea, black tea with 10% skimmed milk, or boiled water (as a control) on three separate occasions under the same conditions. The endothelial function of the brachial artery in the forearm was measured by high resolution ultrasound before and two hours after drinking, with measurements being taken every 15 seconds for up to two minutes a time.
Said first author Dr Mario Lorenz, a molecular biologist: “We found that, whereas drinking tea significantly increased the ability of the artery to relax and expand to accommodate increased blood flow compared with drinking water, the addition of milk completely prevents the biological effect. To extend our findings to a functional model, we determined vasodilation in rat aortic rings by exposing them to tea on its own and tea with individual milk proteins added, and got the same result.”
Milk contains a number of different proteins: by testing each one separately, the researchers found that it was the three caseins that accounted for the inhibiting effect, probably by forming complexes with tea catechins.
Said Dr Stangl: “The well-established benefits of tea have been described in many studies. Our results thus provide a possible explanation for the lack of beneficial effects of tea on the risk of heart disease in the UK, a country where milk is usually added.”
She said their findings could also have implications for cancer, against which tea has also been shown to be protective. “Since milk appears to modify the biological activities of tea ingredients, it is likely that the anti-tumour effects of tea could be affected as well. I think it is essential that we re-examine the association between tea consumption and cancer protection, to see if that is the case.”
Said Dr Lorenz: “It is important to bear in mind that green tea is almost exclusively drunk without milk. So we are talking only about those countries and regions where black tea is consumed and where milk is added. We certainly don’t want to dismiss the consumption of black tea: the results of our study merely attempt to encourage people to consider that, while the addition of milk may improve its taste, it may also lower its health-protective properties.”
Dr Stangl said that another important lesson from their research was that it was vital in nutritional studies to exclude confounding factors as far as possible. Often, the effects of a single nutritional compound or beverage such as red wine, olive oil and so on, are analysed. But, it is difficult to assign clearly the observed effects and separate them from the surrounding food matrix (such as adding milk) that may bias results. It was therefore important to collect all data accurately and include potentially confounding factors in the analysis.
She said that the team was now in the process of comparing the effects of green and black tea on vascular function. “It’s an ongoing question whether green tea, with its higher catechin content, is superior to black tea in regard to endothelial function. In addition, because of the antiatherogenic potential of tea ingredients, we want to investigate the effects of the ingredients on chronic cardiovascular processes such as the development of restenosis (re-narrowing of arteries) after catheter procedures.”
Drinking very hot tea can increase the risk of throat cancer
People are advised to wait a few minutes before drinking a cup of freshly-boiled tea today as a new study, published on bmj.com, finds that drinking very hot tea (70°C or more) can increase the risk of cancer of the oesophagus, the muscular tube that carries food from the throat to the stomach.
The study was carried out in northern Iran, where large amounts of hot tea are drunk every day.
But an accompanying editorial says these findings are not cause for alarm and the general advice is to allow foods and beverages to cool a little before swallowing.
Cancers of the oesophagus kill more than 500,000 people worldwide each year and oesophageal squamous cell carcinoma (OSCC) is the commonest type. In Europe and America, it is mainly caused by tobacco and alcohol use and is more common in men than in women, but drinking hot beverages is also thought to be a risk factor.
Golestan Province in northern Iran has one of the highest rates of OSCC in the world, but rates of smoking and alcohol consumption are low and women are as likely to have a diagnosis as men. Tea drinking, however, is widespread, so researchers set out to investigate a possible link between tea drinking habits and risk of OSCC.
They studied tea drinking habits among 300 people diagnosed with OSCC and a matched group of 571 healthy controls from the same area. Nearly all participants drank black tea regularly, with an average volume consumed of over one litre a day.
Compared with drinking warm or lukewarm tea (65°C or less), drinking hot tea (65-69°C) was associated with twice the risk of oesophageal cancer, and drinking very hot tea (70°C or more) was associated with eight-fold increased risk.
Likewise, compared with drinking tea four or more minutes after being poured, drinking tea less than two minutes after pouring was associated with a five-fold higher risk.
There was no association between the amount of tea consumed and risk of cancer.
To minimise errors between reported and actual tea temperatures, the researchers then measured the actual temperature that tea was consumed by nearly 50,000 residents of the same area. This ranged from less than 60°C to more than 70°C and there was a moderate agreement between reported tea drinking temperature and actual temperature measurements.
Our results show a strong increase in the risk of oesophageal squamous cell carcinoma associated with drinking hot or very hot tea, say the authors.
Previous studies from the United Kingdom have reported an average temperature preference of 56-60°C among healthy populations.
They suggest that informing the population about the hazards of drinking hot tea may be helpful in reducing the incidence of oesophageal cancer in Golestan and in other high risk populations where similar habits are prevalent.
These results provide persuasive evidence that drinking tea at temperatures greater than 70°C markedly increases the risk of oesophageal squamous cell carcinoma, says David Whiteman from the Queensland Institute of Medical Research in Australia in an accompanying editorial.
This report also lends support to the notion that thermal injury may be a cause of epithelial cancers, though he points out that the way in which heat promotes tumour development is not clear and warrants further investigation.
However, he stresses that these findings are not cause for alarm, and they should not reduce public enthusiasm for the time honoured ritual of drinking tea. Instead he suggests waiting at least four minutes before drinking a cup of freshly boiled tea, or more generally allowing foods and beverages to cool from "scalding" to "tolerable" before swallowing.
Green tea boosts your brain
Green
tea is said to have many putative positive effects on health. Now, researchers
at the University of Basel are reporting first evidence that green tea extract
enhances the cognitive functions, in particular the working memory. The Swiss
findings suggest promising clinical implications for the treatment of cognitive
impairments in psychiatric disorders such as dementia. The academic journal Psychopharmacology has published their
results.
In
the past the main ingredients of green tea have been thoroughly studied in
cancer research. Recently, scientists have also been inquiring into the
beverage's positive impact on the human brain. Different studies were able to
link green tea to beneficial effects on the cognitive performance. However, the
neural mechanisms underlying this cognitive enhancing effect of green tea
remained unknown.
Better
memory
In
a new study, the researcher teams of Prof. Christoph Beglinger from the
University Hospital of Basel and Prof. Stefan Borgwardt from the Psychiatric
University Clinics found that green tea extract increases the brain's effective
connectivity, meaning the causal influence that one brain area exerts over
another. This effect on connectivity also led to improvement in actual
cognitive performance: Subjects tested significantly better for working memory
tasks after the admission of green tea extract.
For
the study healthy male volunteers received a soft drink containing several
grams of green tea extract before they solved working memory tasks. The
scientists then analyzed how this affected the brain activity of the men using
magnetic resonance imaging (MRI). The MRI showed increased connectivity between
the parietal and the frontal cortex of the brain. These neuronal findings
correlated positively with improvement in task performance of the participants.
«Our findings suggest that green tea might increase the short-term synaptic
plasticity of the brain», says Borgwardt.
Clinical
implications
The
research results suggest promising clinical implications: Modeling effective
connectivity among frontal and parietal brain regions during working memory processing
might help to assess the efficacy of green tea for the treatment of cognitive
impairments in neuropsychiatric disorders such as dementia.
Green tea may help reduce prostate cancer in men at high risk
Prostate cancer is the second most common type of cancer
in men and is predicted to result in an estimated 220,00 cases in the United
States in 2015. In recent years, an emphasis has been placed on chemoprevention
- the use of agents to prevent the development or progression of prostate
cancer. A team of researchers led by Nagi B. Kumar, Ph.D., R.D., F.A.D.A. at
Moffitt Cancer Center recently published results of a randomized trial that
assessed the safety and effectiveness of the active components in green tea to
prevent prostate cancer development in men who have premalignant lesions. The
results will be presented at the 2015 American Society of Clinical Oncology
(ASCO) Annual Meeting in Chicago.
Twenty percent of green tea is consumed in Asian countries
where prostate cancer death rates are among the lowest in the world and the
risk of prostate cancer appears to be increased among Asian men who abandon
their original dietary habits upon migrating to the U.S.
Laboratory studies have shown that substances in green tea
called, "catechins" inhibit cancer cell growth, motility and
invasion, and stimulate cancer cell death. Green tea catechins also prevent and
reduce tumor growth in animal models. Epigallocatechin-3-gallate (EGCG) is the
most abundant and potent catechin found in green tea responsible for these
cancer prevention effects.
The goal of this trial was to evaluate if a one-year
intervention with green tea catechins could suppress prostate cancer development
in men who had high-grade intraepithelial neoplasia (HGPIN) or atypical small
acinar proliferation (ASAP). The researchers used decaffeinated green tea
capsules called Polyphenon E that contained a mixture of catechins that
predominantly contained EGCG at a dose of 200 mgs twice a day.
The researchers compared Polyphenon E in 49 men to placebo
tablets in 48 men over a 1 year treatment period. Overall, the difference in
the number of prostate cancer cases at the end of 1 year between the two
treatment groups was not statistically significant. However, in men who only
had HGPIN at the beginning of the trial, they observed a lower combined rate of
ASAP and prostate cancer development with Polyophenon E. ASAP is an entity that
reflects a broad group of lesions in the prostate with insufficient changes in
the cells to be definitively diagnosed as prostate cancer. Additionally, men on
Polyphenon E had a significant decrease in prostate-specific antigen (PSA)
levels. PSA is a biomarker that in combination with other risk factors is used
to screen patients for prostate cancer, and high levels signify a higher risk
of prostate cancer.
The Moffitt researchers observed a significant increase in
the levels of EGCG in the blood plasma of men on Polyphenon E, and the capsules
at this dose were tolerated in this group of men.Green tea found to reduce rate of some GI cancers
Women who drink green tea may lower their risk of developing some digestive system cancers, especially cancers of the stomach/esophagus and colorectum, according to a study led by researchers from Vanderbilt-Ingram Cancer Center.
The study by lead author Sarah Nechuta, Ph.D., MPH, assistant professor of Medicine, was published online in advance of the Nov. 1, 2012 edition of the American Journal of Clinical Nutrition. Wei Zheng, M.D., Ph.D., MPH, professor of Medicine, chief of the Division of Epidemiology and director of the Vanderbilt Epidemiology Center, was the principal investigator for the study.
To determine green tea's impact on cancer risk, the investigators surveyed women enrolled in the Shanghai Women's Health Study, a population-based study of approximately 75,000 middle-aged and older Chinese women. During the initial interview participants were asked if they drank tea, the type of tea consumed and how much they consumed. Most of the Chinese women reported drinking primarily green tea.
The researchers found that regular tea consumption, defined as tea consumption at least three times a week for more than six months, was associated with a 17 percent reduced risk of all digestive cancers combined. A further reduction in risk was found to be associated with an increased level of tea drinking. Specifically, those who consumed about two to three cups per day (at least 150 grams of tea per month) had a 21 percent reduced risk of digestive system cancers.
The trend toward fewer digestive cancers was strongest for stomach/esophageal and colorectal cancers.
"For all digestive system cancers combined, the risk was reduced by 27 percent among women who had been drinking tea regularly for at least 20 years," said Nechuta. "For colorectal cancer, risk was reduced by 29 percent among the long-term tea drinkers. These results suggest long-term cumulative exposure may be particularly important."
Tea contains polyphenols or natural chemicals that include catechins like EGCG and ECG. Catechins have antioxidant properties and may inhibit cancer by reducing DNA damage and blocking tumor cell growth and invasion.
The researchers also asked about other lifestyle factors including the kinds of food eaten regularly, exercise habits, education level and occupation. Women who had ever smoked or who drank alcohol were excluded from the study.
Regular tea drinkers in the study were younger, had higher education, exercised more and consumed more fruits and vegetables. While the researchers adjusted for these factors, they could not rule out an effect from these and other unmeasured lifestyle habits.
The study was conducted in nonsmoking and nondrinking Chinese women to minimize the potential influence of these two risk factors on the results for tea consumption and digestive system cancer risk.
Green Tea Fights Prostate Cancer
Six cups of green tea a day may slow the progression of prostate cancer, a new study suggests.
The finding stems from research that showed prostate patients scheduled for a type of surgery known as a prostatectomy, where the prostate is removed, reduced their levels of some disease-associated inflammation by drinking lots of brewed green tea in the weeks preceding the operation. And that reduction in inflammation may inhibit tumor growth, the researchers suggested.
Their results were to be presented at the October, 2012 American Association for Cancer Research's annual prevention conference in Anaheim, Calif.
The notion that the polyphenol compounds found in green tea might have a protective effect against prostate cancer has yet to be confirmed outside a laboratory setting. However, this latest report builds on previous Italian research that suggested that consuming green tea extract may help lower the risk that a precancerous condition will develop into full-blown prostate cancer.
And related research that was also presented at the cancer research conference suggested that the flavonoids found in fruits and vegetables may be associated with a lower risk of developing aggressive prostate cancer.
However, at least one urologist, Dr. Mark Soloway, chairman emeritus of urology at the University of Miami Miller School of Medicine, pointed to the new study's limitations, and said it was too soon to say that green tea had any impact on prostate cancer.
Scientific findings presented at meetings should be viewed as preliminary until published in a peer-reviewed journal.
In this latest green tea study, men who drank the beverage for three to eight weeks prior to surgery experienced a noticeable drop in both serum prostate-specific antigen (PSA) concentrations and PSA protein expression by the time they went under the knife. The fall-off in such telltale signs of disease was accompanied by reductions in both disease-linked inflammation and oxidative DNA damage, the study authors said.
"To see this effect, you would need to drink a lot of green tea," stressed study author Susanne Henning, a registered dietician and adjunct professor with the University of California, Los Angeles David Geffen School of Medicine. "Two cups a day is not going to help. In fact, we had our men drink six cups spread out all throughout the day, which I think was beneficial because green tea polyphenols are excreted very rapidly, so if you drink it that way you keep your levels up. And that seems to be the important factor in keeping the protection going."
To explore the anti-cancer potential of green tea, the authors focused on 67 prostate cancer patients, all of whom were weeks away from surgery. About half the men were randomly assigned to a six-cup-a-day regimen of green tea leading up to surgery, while the others consumed water instead.
The result: Blood and urine samples analyzed alongside tissue samples taken during surgery revealed that the green tea group fared significantly better on key signs of inflammation, PSA levels and expression and DNA damage.
However, no notable difference was found between the two groups in terms of tumor cell growth.
Henning stressed the need for more research on the potential green-tea/prostate cancer connection, and her team is currently planning new animal investigations involving combinations of green tea and other natural foods.
While this research showed an association between green tea and prostate cancer, it did not prove a cause-and-effect link.
"Actually, several food agents have been under investigation for their protective impact," she noted. "Lycopene and omega-3 fatty acids, for example. So, I would say that if you have cancer and you want to make a decision about all of this, then think of incorporating all of those as a part of a lifestyle change. I know that if I was diagnosed with prostate cancer, I would try to change my lifestyle. And that would mean, in addition to eating lots of fruits and vegetables and trying to lose weight and exercising, that I would definitely drink green tea."
The University of Miami's Soloway said that while drinking green tea probably does not have a downside, this "limited study" does not confirm its impact as a prostate cancer intervention.
"[There's] not much solid data to prove it," he said. "This is a small study, and it would take a longer study with hundreds of patients to 'prove' its benefit."
Soloway also noted that the jury is still out on whether inflammation even plays a significant role in cancer development. "It is very much a question," he said. "Not proven at all."
But, he agreed that until larger studies come along to explore green tea's potential, "it might be worth giving it a shot."
Green tea boosts brain cell production to aid memory
It has long been believed that drinking green tea is good for the memory. Now researchers have discovered how the chemical properties of China's favorite drink affect the generation of brain cells, providing benefits for memory and spatial learning. The research is published in Molecular Nutrition & Food Research.
"Green tea is a popular beverage across the world," said Professor Yun Bai from the Third Military Medical University, Chongqing, China. "There has been plenty of scientific attention on its use in helping prevent cardiovascular diseases, but now there is emerging evidence that its chemical properties may impact cellular mechanisms in the brain."
Professor Bai's team focused on the organic chemical EGCG, (epigallocatechin-3 gallate) a key property of green tea. While EGCG is a known anti-oxidant, the team believed it can also have a beneficial effect against age-related degenerative diseases.
"We proposed that EGCG can improve cognitive function by impacting the generation of neuron cells, a process known as neurogenesis," said Bai. "We focused our research on the hippocampus, the part of the brain which processes information from short-term to long-term memory."
The team found that ECGC boosts the production of neural progenitor cells, which like stem cells can adapt, or differentiate, into various types of cells. The team then used laboratory mice to discover if this increased cell production gave an advantage to memory or spatial learning.
"We ran tests on two groups of mice, one which had imbibed ECGC and a control group," said Bai. "First the mice were trained for three days to find a visible platform in their maze. Then they were trained for seven days to find a hidden platform."
The team found that the ECGC treated mice required less time to find the hidden platform. Overall the results revealed that EGCG enhances learning and memory by improving object recognition and spatial memory.
"We have shown that the organic chemical EGCG acts directly to increase the production of neural progenitor cells, both in glass tests and in mice," concluded Bai. "This helps us to understand the potential for EGCG, and green tea which contains it, to help combat degenerative diseases and memory loss."
Green Tea Compound is Effective in Treating Genetic Disorder and Two Types of Tumors
A compound found in green tea shows great promise for the development of drugs to treat two types of tumors and a deadly congenital disease. The discovery is the result of research led by Principal Investigator, Dr. Thomas Smith at The Donald Danforth Plant Science Center and his colleagues at The Children’s Hospital of Philadelphia. Their findings are published in the recent article, “Green Tea Polyphenols Control Dysregulated Glutamate Dehydrogenase In Transgenic Mice By Hijacking The ADP Activation Site” in The Journal of Biological Chemistry.
Glutamate dehydrogenase (GDH) is found in all living organisms and is responsible for the digestion of amino acids. In animals, GDH is controlled by a complex network of metabolites. For decades it was not clear why animals required such regulation but other kingdoms did not. This was partially answered by the Stanley group’s finding that a deadly congenital disease, hyperinsulinism/hyperammonemia (HHS), is caused by the loss of some of this regulation. In this disorder, patients (typically children) respond to the consumption of protein by over secreting insulin, becoming severely hypoglycemic, often leading to death.
Using atomic structures to understand the differences between animals and plants, Dr. Smith and his colleagues discovered that two compounds found naturally in green tea are able to compensate for this genetic disorder by turning off GDH in isolated and when the green tea compounds were administered orally. The Smith lab also used X-ray crystallography to determine the atomic structure of these green tea compounds bound to the enzyme. With this atomic information, they hope to be able to modify these natural compounds to design and develop better drugs.
Interestingly, two other research groups have validated and extended these findings to demonstrate that blocking GDH with green tea is very effective at killing two different kinds of tumors; glioblastomas, an aggressive type of brain tumor, and tuberous sclerosis complex disorder, a genetic disease that causes non-malignant tumors to grow on a number of organs.
Green tea has a powerful ability to increase the number of “regulatory T cells”
One of the beneficial compounds found in green tea has a powerful ability to increase the number of “regulatory T cells” that play a key role in immune function and suppression of autoimmune disease, according to new research in the Linus Pauling Institute at Oregon State University.
This may be one of the underlying mechanisms for the health benefits of green tea, which has attracted wide interest for its ability to help control inflammation, improve immune function and prevent cancer.
Pharmaceutical drugs are available that perform similar roles and have been the subject of much research, scientists say, but they have problems with toxicity. A natural food product might provide a long-term, sustainable way to accomplish this same goal without toxicity, researchers said.
“This appears to be a natural, plant-derived compound that can affect the number of regulatory T cells, and in the process improve immune function,” said Emily Ho, an LPI principal investigator and associate professor in the OSU Department of Nutrition and Exercise Sciences.
“When fully understood, this could provide an easy and safe way to help control autoimmune problems and address various diseases,” Ho said.
The findings have been published in Immunology Letters, a professional journal.
There are many types of cells that have different roles in the immune system, which is a delicate balancing act of attacking unwanted invaders without damaging normal cells. In autoimmune diseases, which can range from simple allergies to juvenile diabetes or even terminal conditions such as Lou Gehrig’s disease, this process goes awry and the body mistakenly attacks itself.
Some cells exist primarily to help control that problem and dampen or “turn off” the immune system, including regulatory T cells. The number and proper function of those regulatory T cells, in turn, is regulated by other biological processes such as transcription factors and DNA methylation.
In this study, OSU scientists did experiments with a compound in green tea, a polyphenol called EGCG, which is believed to be responsible for much of its health benefits and has both anti-inflammatory and anti-cancer characteristics. They found it could cause a higher production of regulatory T cells. Its effects were not as potent as some of those produced by prescription drugs, but it also had few concerns about long-term use or toxicity.
“EGCG may have health benefits through an epigenetic mechanism, meaning we aren’t changing the underlying DNA codes, but just influencing what gets expressed, what cells get turned on,” Ho said. “And we may be able to do this with a simple, whole-food approach.”
Laboratory studies done with mice, Ho said, showed that treatment with EGCG significantly increased the numbers and frequencies of regulatory T cells found in spleen and lymph notes, and in the process helped to control the immune response.
“Epigenetic regulation can be potentially exploited in generating suppressive regulatory T cells for therapeutic purposes, and is of significant clinical importance for the suppression of autoimmune diseases,” the researchers said in their study.
Green tea enhances bone health and reduces inflammation
Tea has for generations been an integral infusion worldwide, carrying both epicurean and economic significance. But, does it impart honest-to-goodness health benefits? In other words, is its persistence in the human diet perhaps coincident with enhanced quality (or quantity) of life?
Dr. Chwan-Li (Leslie) Shen, an associate professor and a researcher at the Laura W. Bush Institute for Women's Health at the Texas Tech University Health Sciences Center, is convinced that the answer to this question is a resounding yes – especially if the tea is of the "green" variety. Green tea, historically consumed in the Orient and now an international mainstay, is chock full of compounds called polyphenols known for their potent antioxidant activity. Dozens of epidemiological (observational) studies have shown that people who consume the highest levels of green tea polyphenols (GTP) tend to have lower risks of several chronic degenerative diseases such as cardiovascular disease and osteoporosis. These findings have been followed up with animal studies, including some conducted by Shen, suggesting that the mechanism behind this correlation may have to do with lowering chronic levels of inflammation.
Originally from Taiwan, Dr. Shen has now spent over 2 decades studying how and why some Eastern lifestyle norms (such as drinking green tea) might be beneficial for Westerners as well. For instance, she has developed an animal model (the ovariectomized, middle-aged female rat). With this model Dr. Shen and her team can effectively study the effects of green tea consumption on protection against breakdown of the bone's microarchitecture. In humans, this can lead to osteoporosis, a condition common to older women. It is Dr Shen's hope that what she learns from her animal models might also be applicable to postmenopausal women.
In Shen's most recent research, she focused on postmenopausal women and investigated the potential for green tea to work synergistically with tai chi – a traditional Chinese form of moderately intense aerobic fitness activity grounded in mind-body philosophy – in enhancing bone strength. The results of this work, which was funded by the National Institutes of Health/National Center for Complementary and Alternative Medicine, will be presented as a poster at the Experimental Biology meetings on April 10. Carried out as a double-blind, placebo-controlled, intervention trial (the "holy grail" of scientific studies), this experiment involved 171 postmenopausal women (mean age: ~57 y) who had weak bones but not full-fledged osteoporosis. Subjects were divided into 4 groups:
Placebo: starch pill (placebo) and no tai chi
GTP: green tea polyphenols (500 mg/day) and no tai chi
Placebo+TC: starch pill and tai chi (3 times/week)
GTP+TC: green tea polyphenols and tai chi
The study lasted for 6 months, during which time blood and urine samples were collected and muscle strength assessed.
The results show that consumption of GTP (at a level equivalent to about 4-6 cups of steeped green tea daily) and participation in tai chi independently enhanced markers of bone health by 3 and 6 months, respectively. A similar effect was found for muscle strength at the 6-month time point. Participants taking tai chi classes also reported significant beneficial effects in quality of life in terms of improving their emotional and mental health. Perhaps most remarkable, however, was the substantial effect that both GTP and tai chi had on biological markers of oxidative stress. Because oxidative stress is a main precursor to inflammation, this finding suggests that green tea and tai chi may help reduce the underlying etiology of not only osteoporosis, but other inflammatory diseases as well.
Dr. Shen and colleagues concluded that there is a "favorable effect of modest green tea consumption on bone remodeling in this pre-osteoporotic population" and hope to soon complete a more long-term study utilizing more technically savvy measures of bone density.
Regularly drinking green tea could protect against Alzheimer's and other forms of dementia
Regularly drinking green tea could protect the brain against developing Alzheimer's and other forms of dementia, according to latest research by scientists at Newcastle University.
The study, published in the academic journal Phytomedicine, also suggests this ancient Chinese remedy could play a vital role in protecting the body against cancer.
Led by Dr Ed Okello, the Newcastle team wanted to know if the protective properties of green tea – which have previously been shown to be present in the undigested, freshly brewed form of the drink – were still active once the tea had been digested.
Digestion is a vital process which provides our bodies with the nutrients we need to survive. But, says Dr Okello, it also means that just because the food we put into our mouths is generally accepted to contain health-boosting properties, we can't assume these compounds will ever be absorbed by the body.
"What was really exciting about this study was that we found when green tea is digested by enzymes in the gut, the resulting chemicals are actually more effective against key triggers of Alzheimer's development than the undigested form of the tea," explains Dr Okello, based in the School of Agriculture, Food and Rural Development at Newcastle University.
"In addition to this, we also found the digested compounds had anti-cancer properties, significantly slowing down the growth of the tumour cells which we were using in our experiments."
As part of the research, the Newcastle team worked in collaboration with Dr Gordon McDougall of the Plant Products and Food Quality Group at the Scottish Crop Research Institute in Dundee, who developed technology which simulates the human digestive system.
It is this which made it possible for the team to analyse the protective properties of the products of digestion.
Two compounds are known to play a significant role in the development of Alzheimer's disease – hydrogen peroxide and a protein known as beta-amyloid.
Previous studies have shown that compounds known as polyphenols, present in black and green tea, possess neuroprotective properties, binding with the toxic compounds and protecting the brain cells.
When ingested, the polyphenols are broken down to produce a mix of compounds and it was these the Newcastle team tested in their latest research.
"It's one of the reasons why we have to be so careful when we make claims about the health benefits of various foods and supplements," explains Dr Okello.
"There are certain chemicals we know to be beneficial and we can identify foods which are rich in them but what happens during the digestion process is crucial to whether these foods are actually doing us any good."
Carrying out the experiments in the lab using a tumour cell model, they exposed the cells to varying concentrations of the different toxins and the digested green tea compounds.
Dr Okello explained: "The digested chemicals protected the cells, preventing the toxins from destroying the cells.
"We also saw them affecting the cancer cells, significantly slowing down their growth.
"Green tea has been used in Traditional Chinese medicine for centuries and what we have here provides the scientific evidence why it may be effective against some of the key diseases we face today."
The next step is to discover whether the beneficial compounds are produced during digestion after healthy human volunteers consume tea polyphenols. The team has already received funding from the Biotechnology and Biological Sciences Research Council (BBSRC) to take this forward.
Dr Okello adds: "There are obviously many factors which together have an influence on diseases such as cancer and dementia - a good diet, plenty of exercise and a healthy lifestyle are all important."
Red wine and green tea halt prostate cancer growth
In what could lead to a major advance in the treatment of prostate cancer, scientists now know exactly why polyphenols in red wine and green tea inhibit cancer growth. This new discovery, published online in The FASEB Journal (http://www.fasebj.org), explains how antioxidants in red wine and green tea produce a combined effect to disrupt an important cell signaling pathway necessary for prostate cancer growth. This finding is important because it may lead to the development of drugs that could stop or slow cancer progression, or improve current treatments.
"Not only does SphK1/S1P signaling pathway play a role in prostate cancer, but it also plays a role in other cancers, such as colon cancer, breast cancer, and gastric cancers," said Gerald Weissmann, MD, editor-in-chief of The FASEB Journal. "Even if future studies show that drinking red wine and green tea isn't as effective in humans as we hope, knowing that the compounds in those drinks disrupts this pathway is an important step toward developing drugs that hit the same target."
Scientists conducted in vitro experiments which showed that the inhibition of the sphingosine kinase-1/sphingosine 1-phosphate (SphK1/S1P) pathway was essential for green tea and wine polyphenols to kill prostate cancer cells. Next, mice genetically altered to develop a human prostate cancer tumor were either treated or not treated with green tea and wine polyphenols. The treated mice showed reduced tumor growth as a result of the inhibited SphK1/S1P pathway. To mimic the preventive effects of polyphenols, another experiment used three groups of mice given drinking water, drinking water with a green tea compound known as EGCg, or drinking water with a different green tea compound, polyphenon E. Human prostate cancer cells were implanted in the mice and results showed a dramatic decrease in tumor size in the mice drinking the EGCg or polyphenon E mixtures.
"The profound impact that the antioxidants in red wine and green tea have on our bodies is more than anyone would have dreamt just 25 years ago," Weissmann added. "As long as they are taken in moderation, all signs show that red wine and green tea may be ranked among the most potent 'health foods' we know."
Green tea fights lung cancer risk for smokers
Drinking green tea could modulate the effect of smoking on lung cancer. Results of this hospital-based, randomized study conducted in Taiwan were presented at the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer, held there from Jan. 11-14, 2010.
"Lung cancer is the leading cause of all cancer deaths in Taiwan," said I-Hsin Lin, M.S., a student at Chung Shan Medical University in Taiwan. "Tea, particularly green tea, has received a great deal of attention because tea polyphenols are strong antioxidants, and tea preparations have shown inhibitory activity against tumorigenesis."
However, previous studies of green tea have been inhibited by the flaws of the epidemiologic model with its inherent biases.
Lin and colleagues enrolled 170 patients with lung cancer and 340 healthy patients as controls. The researchers administered questionnaires to obtain demographic characteristics, cigarette smoking habits, green tea consumption, dietary intake of fruits and vegetables, cooking practices and family history of lung cancer. They also performed genotyping on insulin-like growth factors as polymorphisms on the following insulin-like growth factors: IGF1, IGF2 and IGFBP3, which have all been reported to be associated with cancer risk.
Among smokers and non-smokers, those who did not drink green tea had a 5.16-fold increased risk of lung cancer compared with those who drank at least one cup of green tea per day. Among smokers, those who did not drink green tea at all had a 12.71-fold increased risk of lung cancer compared with those who drank at least one cup of green tea per day.
Lin and colleagues suspect genetics may play a role in this risk differential. Green tea drinkers with non-susceptible IGF1 (CA)19/(CA)19 and (CA)19/X genotypes reported a 66 percent reduction in lung cancer risk as compared with green tea drinkers carrying the IGF1 X/X genotype.
Heavy smokers carrying susceptible IGF1, IGF2 and IGFBP3 genotypes also had a higher risk of lung cancer compared with nonsmokers carrying non-susceptible IGF1, IGF2 and IGFBP3 genotypes.
"Our study may represent a clue that in the case of lung cancer, smoking-induced carcinogenesis could be modulated by green tea consumption and the growth factor environment," said Lin.
Green tea fights oral cancer
Green tea extract has shown promise as cancer prevention agent for oral cancer in patients with a pre-malignant condition known as oral leukoplakia, according to researchers at The University of Texas M. D. Anderson Cancer Center.
The study, published online in Cancer Prevention Research, is the first to examine green tea as a chemopreventative agent in this high-risk patient population. The researchers found that more than half of the oral leukoplakia patients who took the extract had a clinical response.
Long investigated in laboratory, epidemiological and clinical settings for several cancer types, green tea is rich in polyphenols, which have been known to inhibit carcinogenesis in preclinical models. Still, clinical results have been mixed.
"While still very early, and not definitive proof that green tea is an effective preventive agent, these results certainly encourage more study for patients at highest risk for oral cancer," said Vassiliki Papadimitrakopoulou, M.D., professor in M. D. Anderson's Department of Thoracic/Head and Neck Medical Oncology, and the study's senior author. "The extract's lack of toxicity is attractive - in prevention trials, it's very important to remember that these are otherwise healthy individuals and we need to ensure that agents studied produce no harm."
In the Phase II dose-finding study, 41 M. D. Anderson oral leukoplakia patients were randomized between August 2002 and March 2008 to receive either green tea extract or placebo. Participants took the extract, an oral agent, for three months at one of three doses - 500 per meter squared of body mass (mg/m2); 750 mg/m2 or 1,000 mg/m2 - three times daily. To best assess biomarkers, participants also underwent a baseline and 12-week biopsy, an important component in the design of the study, the researchers say.
"Collecting oral tissue biopsies was essential in that it allowed us to learn that not only did the green tea extract appear to have benefit for some patients, but we pointed to anti-angiogenic effects as a potential mechanism of action," said Anne Tsao, M.D., assistant professor in the Department of Thoracic/Head and Neck Medical Oncology, and the study's first author. "While preliminary because our patient population was so small, this gives us direction for further study."
Of those taking green tea at the two highest doses, 58.8 percent had a clinical response, compared with 36.4 percent in the lowest extract dose and 18.2 percent in the placebo arm. At an extended follow-up with a mean of 27.5 months, 15 participants had developed oral cancer, with a median time to disease development of 46.4 months.
Although not statistically significant, the green tea extract also improved histology and trended towards an improvement in a number of biomarkers that may play a vital role in predicting cancer development.
Another important finding, say the researchers, was that that the extract was well tolerated. Side effects, including insomnia and nervousness, were mostly seen in the high-dose group but produced no significant toxicity.
"While these are encouraging findings, much more research must be done before we can conclude that green tea may prevent oral or any other type of cancer. It's also important to remind people that this trial enrolled very few participants who, at the highest dose levels took the equivalent of eight cups of green tea three times a day," said Papadimitrakopoulo. "We need to further understand if green tea offers longer-term prevention effects for patients."
Papadimitrakopoulo and Tsao think that future studies with green tea in this high-risk population should focus on participants being exposed to the supplement for a longer time period. The researchers also stressed that the green tea extract studied in this trial was never sold over-the-counter and/or the Internet, both of which are not highly regulated. Rather, the compound was exclusively developed as a pharmaceutical.
According to the American Cancer Society, more than 35,720 are expected to be diagnosed with oral and/or pharynx cancer and the five year survival rate is less than 50 percent.
Green tea fights several kinds of cancer
A large new review of studies that examined the affect of green tea on cancer prevention has yielded promising results.
Researchers looked at 51 medium- to high-quality studies that included more than 1.6 million participants. The studies focused on the relationship between green tea consumption and a variety of cancers, including breast, lung, digestive tract, urological prostate, gynecological and oral cancers.
The comprehensive review analyzed studies conducted from 1985 through 2008. Many of the reviewed studies took place in Asia, where tea drinking is widespread and part of the daily routine for many.
Three types of tea — black, green and oolong — come from the plant Camellia sinensis, and all contain polyphenols. Catechins, a subgroup of the polyphenols, are powerful antioxidants. Some say the polyphenols in green tea are unique, preventing cell growth and thus having the potential to prevent cancer.
The review found that green tea had limited benefits for liver cancer, but found conflicting evidence for other gastrointestinal cancers, such as cancer of the esophagus, colon or pancreas. One study found a decreased risk of prostate cancer for men who consumed higher quantities of green tea or its extracts.
The review did not find any benefit for preventing death from gastric cancer, and found that green tea might even increase the risk of urinary bladder cancer. Despite conflicting findings, there was “limited moderate to strong evidence” of a benefit for lung, pancreatic and colorectal cancer. None of the studies that simply observed a group of people over time found a benefit for breast cancer prevention. However, both of the case control studies — which compare people without a condition to people with it — found a positive association between green tea consumption and a decreased risk of breast cancer.
Nagi Kumar, Ph.D., director of Nutrition Research at Moffitt Cancer Center in Tampa, Fla., is optimistic about the potential for green tea in cancer prevention. “The substances found in green tea are certainly promising,” Kumar said. “The field now has progressed to where we [can]…test the effectiveness and safety of green tea polyphenols using a drug form similar to the constituents in tea to see if we can prevent cancer progression. Time will tell.”
Kumar said the Cochrane review was “more an inventory of studies completed rather than a systematic scientific review,” adding that “the discussion lacks a scientific approach in the interpretation of the discordant findings.”
Kumar also noted that several groups are conducting randomized clinical trials, including one comprising six institutions: the Moffitt Cancer Center and the James A Haley VA Medical Center, University of Chicago, Jefferson in Philadelphia, University of Florida and Louisiana State University.
Both scientists agreed that more research is a good idea. Boehm said she highly recommends the conduction of a large, well-designed, study with adequate green tea consumption levels.
“The review provides where we have been in this field of research and where we are going and how much more we have on hand,” Kumar said. “Although not as thorough as I would like it, it is a good quality review.”
Therefore, while the questions about green tea consumption and cancer prevention remain unanswered, one thing remains clear: It is fine to consume green tea if you enjoy it and it might prove beneficial in the over time.
“If not exceeding the daily recommended allowance those who enjoy a cup of green tea should continue its consumption,” Boehm said. “Drinking green tea appears to be safe at regular, habitual and moderate use at its recommended dosage of up to 1200 ml/day.” That comes to a little over five cups a day.
Green tea fights prostate cancer
According to results of a study published in Cancer Prevention Research, a journal of the American Association for Cancer Research, men with prostate cancer who consumed the active compounds in green tea demonstrated a significant reduction in serum markers predictive of prostate cancer progression.
"The investigational agent used in the trial, Polyphenon E (provided by Polyphenon Pharma) may have the potential to lower the incidence and slow the progression of prostate cancer," said James A. Cardelli, Ph.D., professor and director of basic and translational research in the Feist-Weiller Cancer Center, LSU Health Sciences Center-Shreveport.
Green tea is the second most popular drink in the world, and some epidemiological studies have shown health benefits with green tea, including a reduced incidence of prostate cancer, according to Cardelli. However, some human trials have found contradictory results. The few trials conducted to date have evaluated the clinical efficacy of green tea consumption and few studies have evaluated the change in biomarkers, which might predict disease progression.
Cardelli and colleagues conducted this open-label, single-arm, phase II clinical trial to determine the effects of short-term supplementation with green tea's active compounds on serum biomarkers in patients with prostate cancer. The biomarkers include hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and prostate specific antigen (PSA). HGF and VEGF are good prognostic indicators of metastatic disease.
The study included 26 men, aged 41 to 72 years, diagnosed with prostate cancer and scheduled for radical prostatectomy. Patients consumed four capsules containing Polyphenon E until the day before surgery — four capsules are equivalent to about 12 cups of normally brewed concentrated green tea, according to Cardelli. The time of study for 25 of the 26 patients ranged from 12 days to 73 days, with a median time of 34.5 days.
Findings showed a significant reduction in serum levels of HGF, VEGF and PSA after treatment, with some patients demonstrating reductions in levels of greater than 30 percent, according to the researchers.
Cardelli and colleagues found that other biomarkers were also positively affected. There were only a few reported side effects associated with this study, and liver function remained normal.
Results of a recent year-long clinical trial conduced by researchers in Italy demonstrated that consumption of green tea polyphenols reduced the risk of developing prostate cancer in men with high-grade prostate intraepithelial neoplasia (HGPIN).
"These studies are just the beginning and a lot of work remains to be done, however, we think that the use of tea polyphenols alone or in combination with other compounds currently used for cancer therapy should be explored as an approach to prevent cancer progression and recurrence," Cardelli said.
William G. Nelson, V., M.D., Ph.D., professor of oncology, urology and pharmacology at the Johns Hopkins Kimmel Cancer Center, believes the reduced serum biomarkers of prostate cancer may be attributable to some sort of benefit relating to green tea components.
"Unfortunately, this trial was not a randomized trial, which would have been needed to be more sure that the observed changes were truly attributable to the green tea components and not to some other lifestyle change (better diet, taking vitamins, etc.) men undertook in preparation for surgery," added Nelson, who is also a senior editor for Cancer Prevention Research. However, "this trial is provocative enough to consider a more substantial randomized trial."
In collaboration with Columbia University in New York City, the researchers are currently conducting a comparable trial among patients with breast cancer. They also plan to conduct further studies to identify the factors that could explain why some patients responded more dramatically to Polyphenon E than others. Cardelli suggested that additional controlled clinical trials should be done to see if combinations of different plant polyphenols were more effective than Polyphenon E alone.
"There is reasonably good evidence that many cancers are preventable, and our studies using plant-derived substances support the idea that plant compounds found in a healthy diet can play a role in preventing cancer development and progression," said Cardelli.
Green tea found to reduce rate of some GI cancers
Women who drink green tea may lower their risk of developing some digestive system cancers, especially cancers of the stomach/esophagus and colorectum, according to a study led by researchers from Vanderbilt-Ingram Cancer Center.
The study by lead author Sarah Nechuta, Ph.D., MPH, assistant professor of Medicine, was published online in advance of the Nov. 1, 2012 edition of the American Journal of Clinical Nutrition. Wei Zheng, M.D., Ph.D., MPH, professor of Medicine, chief of the Division of Epidemiology and director of the Vanderbilt Epidemiology Center, was the principal investigator for the study.
To determine green tea's impact on cancer risk, the investigators surveyed women enrolled in the Shanghai Women's Health Study, a population-based study of approximately 75,000 middle-aged and older Chinese women. During the initial interview participants were asked if they drank tea, the type of tea consumed and how much they consumed. Most of the Chinese women reported drinking primarily green tea.
The researchers found that regular tea consumption, defined as tea consumption at least three times a week for more than six months, was associated with a 17 percent reduced risk of all digestive cancers combined. A further reduction in risk was found to be associated with an increased level of tea drinking. Specifically, those who consumed about two to three cups per day (at least 150 grams of tea per month) had a 21 percent reduced risk of digestive system cancers.
The trend toward fewer digestive cancers was strongest for stomach/esophageal and colorectal cancers.
"For all digestive system cancers combined, the risk was reduced by 27 percent among women who had been drinking tea regularly for at least 20 years," said Nechuta. "For colorectal cancer, risk was reduced by 29 percent among the long-term tea drinkers. These results suggest long-term cumulative exposure may be particularly important."
Tea contains polyphenols or natural chemicals that include catechins like EGCG and ECG. Catechins have antioxidant properties and may inhibit cancer by reducing DNA damage and blocking tumor cell growth and invasion.
The researchers also asked about other lifestyle factors including the kinds of food eaten regularly, exercise habits, education level and occupation. Women who had ever smoked or who drank alcohol were excluded from the study.
Regular tea drinkers in the study were younger, had higher education, exercised more and consumed more fruits and vegetables. While the researchers adjusted for these factors, they could not rule out an effect from these and other unmeasured lifestyle habits.
The study was conducted in nonsmoking and nondrinking Chinese women to minimize the potential influence of these two risk factors on the results for tea consumption and digestive system cancer risk.
High and moderate consumption of tea are linked with reduced heart disease
High and moderate consumption of tea are linked with reduced heart disease, according to a study published in Arteriosclerosis, Thrombosis, and Vascular Biology: Journal of the American Heart Association.
Researchers in The Netherlands found:
Drinking more than six cups of tea per day was associated with a 36 percent lower risk of heart disease compared to those who drank less than one cup of tea per day.
Drinking three to six cups of tea per day was associated with a 45 percent reduced risk of death from heart disease, compared to consumption of less than one cup per day.
Green tea may help fight glaucoma and other eye diseases
Scientists have confirmed that the healthful substances found in green tea — renowned for their powerful antioxidant and disease-fighting properties — do penetrate into tissues of the eye. Their new report, the first documenting how the lens, retina, and other eye tissues absorb these substances, raises the possibility that green tea may protect against glaucoma and other common eye diseases. "Green Tea Catechins and Their Oxidative Protection in the Rat Eye" appears in ACS's bi-weekly Journal of Agricultural and Food Chemistry.
Chi Pui Pang and colleagues point out that so-called green tea "catechins" have been among a number of antioxidants thought capable of protecting the eye. Those include vitamin C, vitamin E, lutein, and zeaxanthin. Until now, however, nobody knew if the catechins in green tea actually passed from the stomach and gastrointestinal tract into the tissues of the eye.
Pang and his colleagues resolved that uncertainty in experiments with laboratory rats that drank green tea. Analysis of eye tissues showed beyond a doubt that eye structures absorbed significant amounts of individual catechins. The retina, for example, absorbed the highest levels of gallocatechin, while the aqueous humor tended to absorb epigallocatechin. The effects of green tea catechins in reducing harmful oxidative stress in the eye lasted for up to 20 hours. "Our results indicate that green tea consumption could benefit the eye against oxidative stress," the report concludes.
Antioxidants in green tea may help reduce periodontal disease
With origins dating back over 4,000 years, green tea has long been a popular beverage in Asian culture, and is increasingly gaining popularity in the United States. And while ancient Chinese and Japanese medicine believed green tea consumption could cure disease and heal wounds, recent scientific studies are beginning to establish the potential health benefits of drinking green tea, especially in weight loss, heart health, and cancer prevention. A study recently published in the Journal of Periodontology, the official publication of the American Academy of Periodontology (AAP), uncovered yet another benefit of green tea consumption. Researchers found that routine intake of green tea may also help promote healthy teeth and gums. The study analyzed the periodontal health of 940 men, and found that those who regularly drank green tea had superior periodontal health than subjects that consumed less green tea.
"It has been long speculated that green tea possesses a host of health benefits," said study author Dr. Yoshihiro Shimazaki of Kyushu University in Fukuoka, Japan. "And since many of us enjoy green tea on a regular basis, my colleagues and I were eager to investigate the impact of green tea consumption on periodontal health, especially considering the escalating emphasis on the connection between periodontal health and overall health."
Male participants aged 49 through 59 were examined on three indicators of periodontal disease: periodontal pocket depth (PD), clinical attachment loss (CAL) of gum tissue, and bleeding on probing (BOP) of the gum tissue. Researchers observed that for every one cup of green tea consumed per day, there was a decrease in all three indicators, therefore signifying a lower instance of periodontal disease in those subjects who regularly drank green tea.
Green tea's ability to help reduce symptoms of periodontal disease may be due to the presence of the antioxidant catechin. Previous research has demonstrated antioxidants' ability to reduce inflammation in the body, and the indicators of periodontal disease measured in this study, PD, CAL and BOP, suggest the existence of an inflammatory response to periodontal bacteria in the mouth. By interfering with the body's inflammatory response to periodontal bacteria, green tea may actually help promote periodontal health, and ward off further disease. Periodontal disease is a chronic inflammatory disease that affects the gums and bone supporting the teeth, and has been associated with the progression of other diseases such as cardiovascular disease and diabetes.
"Periodontists believe that maintaining healthy gums is absolutely critical to maintaining a healthy body," says Dr. David Cochran, DDS, PhD, President of the AAP and Chair of the Department of Periodontics at the University of Texas Health Science Center at San Antonio. "That is why it is so important to find simple ways to boost periodontal health, such as regularly drinking green tea – something already known to possess certain health-related benefits."
Green, black tea can reduce stroke risk
Drinking at least three cups of green or black tea a day can significantly reduce the risk of stroke, a new UCLA study has found. And the more you drink, the better your odds of staving off a stroke.
The study results, published in the online edition of Stroke: Journal of the American Heart Association, were presented Feb. 19, 2009 at the American Heart Association's annual International Stroke Conference in San Diego, Calif.
The UCLA researchers conducted an evidence-based review of all human observational studies on stroke and tea consumption found in the PubMed and Web of Science archives. They found nine studies describing 4,378 strokes among nearly 195,000 individuals, according to lead author Lenore Arab, a professor of medicine in the division of general internal medicine and health services research at the David Geffen School of Medicine at UCLA.
"What we saw was that there was a consistency of effect of appreciable magnitude," said Arab, who is also a professor of biological chemistry. "By drinking three cups of tea a day, the risk of a stroke was reduced by 21 percent. It didn't matter if it was green or black tea."
And extrapolating from the data, the effect appears to be linear, Arab said. For instance, if one drinks three cups a day, the risk falls by 21 percent; follow that with another three cups and the risk drops another 21 percent.
This effect was found in tea made from the plant Camellia sinensis, not from herbal teas.
There are very few known ways to reduce the risk of stroke, Arab said. And developing medications for stroke victims is particularly challenging, given that the drug has to get to the stroke-damaged site quickly because damage occurs so fast. Arab said that by the time a stroke victim gets medical care, it's nearly too late to impede the damage.
"That's why these findings are so exciting," she said. "If we can find a way to prevent the stroke, or prevent the damage, that is simple and not toxic, that would be a great advance."
Though no one is certain which compounds in tea are responsible for this effect, researchers have speculated that the antioxidant epigallocatechin gallate (EGCG) or the amino acid theanine may be what helps. Antioxidants are believed to help prevent coronary artery disease.
"And we do know that theanine is nearly 100-percent absorbed," Arab said. "It gets across the blood-brain barrier and it looks a lot like a molecule that's very similar to glutamate, and glutamate release is associated with stroke.
"It could be that theanine and glutamate compete for the glutamate receptor in the brain," she added.
Although a randomized clinical trial is needed to confirm this effect, the findings suggest that drinking three cups of green or black tea a day could help prevent an ischemic stroke.
Green Tea May Help Fight Rheumatoid Arthritis
A new study from the University of Michigan Health System suggests that a compound in green tea may provide therapeutic benefits to people with rheumatoid arthritis.
The study, presented April 29 at the Experimental Biology 2007 in Washington, D.C., looks at a potent anti-inflammatory compound derived from green tea. Researchers found that the compound – called epigallocatechin-3-gallate (EGCG) – inhibited the production of several molecules in the immune system that contribute to inflammation and joint damage in people with rheumatoid arthritis.
The compound from green tea also was found to suppress the inflammatory products in the connective tissue of people with rheumatoid arthritis.
“Our research is a very promising step in the search for therapies for the joint destruction experienced by people who have rheumatoid arthritis,” says Salah-uddin Ahmed, Ph.D., lead researcher on the study. Ahmed, a research investigator with the Division of Rheumatology at the U-M Health System, was selected to present the research at the Experimental Biology meeting as the recipient of the Young Scientist Travel Award, given by the American Society for Pharmacology and Experimental Therapeutics. This study was also selected by the American Society for Nutrition to be featured in a press release.
To conduct the research, the scientists isolated cells called synovial fibroblasts from the joints of patients with rheumatoid arthritis. These fibroblasts – cells that form a lining of the tissue surrounding the capsule of the joints – then were cultured in a growth medium and incubated with the green tea compound.
The fibroblasts were then stimulated with pro-inflammatory cytokine IL-1_, a protein of the immune system known to play an important role in causing joint destruction in people with rheumatoid arthritis.
The researchers looked at whether the green tea compound has the capability to block the activity of two potent molecules, IL-6 and cyclooxygenase-2 (COX-2), which also are actively involved in causing bone erosion in the joints of people with rheumatoid arthritis.
When untreated cells were stimulated with IL-1_, a sequence of molecular events occurred that resulted in production of the bone-destructive molecules. But the scientists found that pre-incubation with EGCG was capable of inhibiting the production of these molecules. EGCG also inhibited the production of prostaglandin E2, a hormone-like substance that causes inflammation in the joints.
The cell signaling pathways that regulate levels of these immune system molecules under both normal and rheumatoid arthritis situations are well studied, and the researchers were able to trace the effects of the green tea compound infusion to see that it worked by inhibiting these pathways.
Ahmed says that these studies suggest that EGCG or molecules that could be derived synthetically from the EGCG found in green tea may be of therapeutic value by inhibiting the joint destruction in rheumatoid arthritis.
Previously, Ahmed and other researchers made another promising finding when EGCG-pretreated synovial fibroblasts were stimulated with the cytokine IL-1_ to study the protective effect of this green tea compound. Compared to untreated synovial fibroblasts, the cells treated with EGCG markedly blocked the ability of IL-1_ to produce the proteins and enzymes that infiltrate the joints of persons with rheumatoid arthritis and cause cartilage degradation.
The laboratory now is focused on the inhibitory role of EGCG in gene expression. The scientists plan to test EGCG in animal models of rheumatoid arthritis to see if it provides similar therapeutic or preventive effects. Ahmed believes that the outcome of these studies will form a strong foundation for future testing of green tea compound in humans with rheumatoid arthritis.
Green tea may help improve bone health
Researchers in Hong Kong are reporting new evidence that green tea — one of the most popular beverages consumed worldwide and now available as a dietary supplement — may help improve bone health. They found that the tea contains a group of chemicals that can stimulate bone formation and help slow its breakdown. Their findings are in ACS' Journal of Agricultural and Food Chemistry, a bi-weekly publication. The beverage has the potential to help in the prevention and treatment of osteoporosis and other bone diseases that affect million worldwide, the researchers suggest.
In the new study, Ping Chung Leung and colleagues note that many scientific studies have linked tea to beneficial effects in preventing cancer, heart disease, and other conditions. Recent studies in humans and cell cultures suggest that tea may also benefit bone health. But few scientific studies have explored the exact chemicals in tea that might be responsible for this effect.
The scientists exposed a group of cultured bone-forming cells (osteoblasts) to three major green tea components — epigallocatechin (EGC), gallocatechin (GC), and gallocatechin gallate (GCG) — for several days. They found that one in particular, EGC, boosted the activity of a key enzyme that promotes bone growth by up to 79 percent. EGC also significantly boosted levels of bone mineralization in the cells, which strengthens bones. The scientists also showed that high concentrations of ECG blocked the activity of a type of cell (osteoclast) that breaks down or weakens bones. The green tea components did not cause any toxic effects to the bone cells, they note.
Green tea may help protect against autoimmune disease
Green tea may help protect against autoimmune disease, Medical College of Georgia researchers say.
Researchers studied an animal model for type I diabetes and primary Sjogren’s Syndrome, which damages the glands that produce tears and saliva.
They found significantly less salivary gland damage in a group treated with green tea extract, suggesting a reduction of the Sjogren’s symptom commonly referred to as dry mouth. Dry mouth can also be caused by certain drugs, radiation and other diseases.
Approximately 30 percent of elderly Americans suffer from degrees of dry mouth, says Dr. Stephen Hsu, a researcher in the MCG School of Dentistry and lead investigator on the study. Only 5 percent of the elderly in China, where green tea is widely consumed, suffer from the problem.
“Since it is an autoimmune disease, Sjogren’s Syndrome causes the body to attack itself and produce extra antibodies that mistakenly target the salivary and lacrimal glands,” he says.
There is no cure or prevention for Sjogren’s Syndrome.
Researchers studied the salivary glands of the water-consuming group and a green tea extract-consuming group to look for inflammation and the number of lymphocytes, a type of white blood cells that gather at sites of inflammation to fend off foreign cells.
The group treated with green tea had significantly fewer lymphocytes, Dr. Hsu says. Their blood also showed lower levels of autoantibodies, protein weapons produced when the immune system attacks itself, he says.
Researchers already know that one component of green tea – EGCG – helps suppress inflammation, according to Dr. Hsu.
“So, we suspected that green tea would suppress the inflammatory response of this disease. Those treated with the green tea extract beginning at three weeks, showed significantly less damage to those glands over time.”
These results, published in a recent issue of Autoimmunity, reinforced findings of a 2005 study showing a similar phenomenon in a Petrie dish, Dr. Hsu says.
Researchers also suspect that the EGCG in green tea can turn on the body’s defense system against TNF-alpha – a group of proteins and molecules involved in systemic inflammation.
TNF-alpha, which is produced by white blood cells, can reach out to target and kill cells.
“The salivary gland cells treated with EGCG had much fewer signs of cell death caused by TNF-alpha,” Dr. Hsu says. “We don’t yet know exactly how EGCG makes that happen. That will require further study. In some ways, this study gives us more questions than answers.”
Further study could help determine green tea’s protective role in other autoimmune diseases, including lupus, psoriasis, scleroderma and rheumatoid arthritis, he says.
Green tea may protect from inflamed bladder
Herbal agents could be used to treat inflammatory bladder diseases, according to a preliminary study that looked at the ability of green tea to protect bladder cells from inflammation. The University of Pittsburgh School of Medicine study, being presented at the 2007 annual meeting of the American Urological Association (AUA) in Anaheim, Calif., found that components of green tea protected bladder cells from damage in culture. The study is Abstract 299 in the AUA proceedings.
Green tea, reported to have many health benefits, is rich in powerful antioxidants that make it a possible remedy for many medical conditions. It is comprised of catechins – plant metabolites that provide it with many anti-oxidative properties.
"We discovered that catechins found in green tea protected both normal and cancerous bladder cells from inflammation when we exposed the cells to hydrogen peroxide," said Michael B. Chancellor, M.D., professor of urology and gynecology at the University of Pittsburgh School of Medicine. "Although further studies are needed, these results indicate herbal supplements from green tea could be a treatment option for various bladder conditions that are caused by injury or inflammation."
In the study, normal and cancerous bladder cells were exposed to two major catechin components of green tea, epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), for 23 hours. Both significantly protected cell lines from exposure to hydrogen peroxide, which damages or kills cells. The concentrations of EGCG and ECG used in the study were at levels that may be achieved through dietary intake.
Approximately ten million American adults have problems controlling their bladders. Bladder disease affects both men and women and can include incontinence or interstitial cystitis, a chronic inflammatory condition that causes frequent, urgent and painful urination and pelvic discomfort.
Green tea may protect brain cells against Parkinson's disease
Does the consumption of green tea, widely touted to have beneficial effects on health, also protect brain cells" Authors of a new study being published in the December 15th issue of Biological Psychiatry share new data that indicates this may be the case. The authors investigated the effects of green tea polyphenols, a group of naturally occurring chemical substances found in plants that have antioxidant properties, in an animal model of Parkinson’s disease.
The authors discovered that green tea polyphenols protect dopamine neurons that increases with the amount consumed. They also show that this protective effect is mediated by inhibition of the ROS-NO pathway, a pathway that may contribute to cell death in Parkinson’s.
Green tea helps beat superbugs
Green tea can help beat superbugs according to Egyptian scientists speaking Monday 31 March 2008 at the Society for General Microbiology’s 162nd meeting being held this week at the Edinburgh International Conference Centre.
The pharmacy researchers have shown that drinking green tea helps the action of important antibiotics in their fight against resistant superbugs, making them up to three times more effective.
Green tea is a very common beverage in Egypt, and it is quite likely that patients will drink green tea while taking antibiotics. The medical researchers wanted to find out if green tea would interfere with the action of the antibiotics, have no effect, or increase the medicines’ effects.
“We tested green tea in combination with antibiotics against 28 disease causing micro-organisms belonging to two different classes,” says Dr Mervat Kassem from the Faculty of Pharmacy at Alexandria University in Egypt. “In every single case green tea enhanced the bacteria-killing activity of the antibiotics. For example the killing effect of chloramphenicol was 99.99% better when taken with green tea than when taken on its own in some circumstances.”
Green tea also made 20% of drug-resistant bacteria susceptible to one of the cephalosporin antibiotics. These are important antibiotics that new drug resistant strains of bacteria have evolved to resist.
The results surprised the researchers, showing that in almost every case and for all types of antibiotics tested, drinking green tea at the same time as taking the medicines seemed to reduce the bacteria’s drug resistance, even in superbug strains, and increase the action of the antibiotics. In some cases, even a low concentration of green tea was effective.
No comments:
Post a Comment