14/12/2007 - The antioxidant effects of green tea polyphenols may protect neurons against the detrimental effects of reactive oxygen species (ROS) and nitric oxide (NO), thereby offering potential benefits for Parkinson’s, says new research from China.

The study, conducted in rats, looked at the effects of green tea polyphenols (GTP) on inhibiting the death of neurons induced by the neurotoxin 6-hydroxydopamine (6-OHDA).

The results are published in the journal Biological Psychiatry.

Parkinson’s disease is a degenerative condition affecting movement and balance in more than one million Americans each year, a figure expected to rise due to ageing populations.

According to background information in the article, the disease is caused by an unrelenting process of cell death affecting the neurons containing pigmented dopamine (DA).

Researchers, led by Baolu Zhao from the Institute of Biophysics, Academia Sinica, Beijing, randomly assigned male Sprague-Dawley rats to one of six groups: control-fed only; control-fed plus 6-OHDA; GTP (150 mg/kg/day) plus 6-OHDA; GTP (450 mg/kg/day) plus 6-OHDA; GTP (150 mg/kg/day) only; GTP (450 mg/kg/day) only.

Green tea contains between 30 and 40 per cent of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3 and 10 per cent. Oolong tea is semi-fermented tea and is somewhere between green and black tea.

The four primary polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC).

The mix used in this new study contained 50 per cent EGCG, 22 per cent ECG, 18 per cent EGC, and 10 per cent EC (Sichuan Full-green Biology Technology).

Zhao and co-workers report that the green tea polyphenols protected against the toxic effects of 6-OHDA, with the higher dose producing a higher protective effect. Most notable, were the inhibition of increases in ROS and NO levels, and subsequent lipid peroxidation.

“This study shows that, in vivo, GTP partially protected dopaminergic neurons (3.7 times more remaining neuron in GTP-treated than vehicle-treated animals) from 6-OHDA-induced cell death through ROS-NO pathway,” wrote the researchers.

Commenting independently on the study, John Krystal, editor of Biological Psychiatry and affiliated with both Yale University School of Medicine and the VA Connecticut Healthcare System said: “If green tea consumption can be shown to have meaningful neuroprotective actions in patients, this would be an extremely important advance.”

He added a note of caution however, saying that many health-related benefits have been reported for a wide variety of naturally-occurring substances with many being contradicted by subsequent clinical trials. This is the case with St. John’s Wort and Ginko Biloba, he said.

“Thus, it is extremely important to identify the putative neuroprotective mechanisms in animal models, as Guo and colleagues have begun to do for Parkinson’s disease,” said Krystal.

Source: Biological Psychiatry (Elsevier)
15 December 2007, Volume 62, Issue 12, Pages 1353-1362
“Protective Effects of Green Tea Polyphenols in the 6-OHDA Rat Model of Parkinson’s Disease Through Inhibition of ROS-NO Pathway”
Authors: Shuhong Guo, J. Yan, T. Yang, X. Yang, E. Bezard and B. Zhao

Washington: Taking a cup of green tea lowers the risk of colorectal cancer, a new research shows. Researchers from the US found a lower risk of colorectal tumors in rodents given a standardised green tea polyphenol preparation, the Science Daily reported. After 34 weeks, the rodents receiving the green tea extract had 55 per cent fewer tumours than the control group and their tumours were 45 per cent smaller. ‘’Our findings show that rats fed a diet containing Polyphenon E, a standardised green tea polyphenol preparation, are less than half as likely to develop colon cancer,’’ study author Hang Xiao, of Rutgers University said. Dr Xiao points out these results are consistent with previously published results , which showed that green tea consumption was associated with lower colon cancer rates in Shanghai, China. In this study, the test animals receiving the green tea extract also weighed about five per cent less than their control group counterparts, a result Dr Xiao attributes to the ability of the green tea polyphenols to block lipid absorption in the body.

THURSDAY, Dec. 6 (HealthDay News) — A gel derived from black raspberries, a fruit beverage and old-fashioned green tea all hold potential promise as ways to treat or prevent different types of cancer, preliminary research suggests.”Until now, foods have not been considered good treatments for chronic illness, especially tackling tumors,” Greg Jardine, a biochemist at Dr. Red Nutraceuticals in Australia, said at a teleconference Thursday. In fact, “foods can be medicine,” added Jardine, co-author of a manufacturer-funded study of a “punch” that appeared to reduce the growth of prostate cancer in mice.

In addition to Jardine’s study, two others — one with people and one with rats — suggest that a black raspberry gel can reduce oral cancer lesions and green tea can prevent colorectal cancer.

The studies, which are all small and need further confirmation, were presented at the American Association for Cancer Research’s Sixth Annual International Conference on Frontiers in Cancer Prevention Research, which runs through Dec. 8 in Philadelphia.

Researchers at Ohio State University and the University of Kentucky are using a gel made of extracts from black raspberries to treat oral lesions, which often begin as growths inside the mouth and threaten to turn into major tumors.

“About 36 percent will progress to oral squamous cell carcinoma, but, at this point, we don’t have the molecular tools to determine which ones will go on to malignancy,” said Dr. Susan Mallery, a professor in the Department of Oral Maxillofacial Surgery and Pathology at Ohio State University’s College of Dentistry.

About 7,500 people in the United States die each year of oral cancer, according to American Cancer Society statistics, and 34,000 new cases are diagnosed annually.

The researchers assigned 30 patients — 20 with precancerous lesions and 10 healthy patients — to apply the gel several times a day. After six weeks of treatment, the grade of the lesions decreased in 35 percent of patients, while it stayed steady in 45 percent of patients and grew in 20 percent, Mallery said.

Patients whose tumors had progressed the least seemed to do the best after undergoing the gel treatment, Mallery said. None of the patients reported side effects.

Why does the gel appear to work? According to Mallery, the active agents appear to be “those chemicals that give it a very rich purple color.” The study authors suspect that the chemicals may help “re-educate” tumor cells, reversing their march toward cancer.

In another study, Australian researchers — funded by Dr. Red Nutraceuticals, the maker of an antioxidant-boosted beverage called “Blueberry Punch” — gave the drink to mice with tumors that were considered equivalent to prostate cancer in humans.

The tumors were 25 percent smaller in eight mice that drank the punch for two weeks, compared to eight mice that did not drink the punch. Jardine said the next step is to figure out if the punch would have a beneficial effect in men. The punch, designed to be a health aid, is sold in Australia and in New Zealand, and is made of fruit concentrates and a variety of extracts, as well as tarragon, turmeric and ginger, he said.

In the third study, researchers from Rutgers University in New Jersey fed chemicals known as polyphenols from green tea to rats that had colorectal cancer. The polyphenols appeared to reduce the size of tumors by 45 percent, the study authors said.

It’s not clear if the polyphenols would have a similar benefit in humans, and the equivalent amount of tea consumption in people would be hefty — four to six cups a day, the researchers said.

Many people are now turning to inexpensive and natural green tea weight loss plans to help them in their weight control efforts. It is simple too. Green tea can be drunk like any other tea, usually without milk or sweeteners, or if you do not like the taste you can purchase green tea extract.

Research has shown that green tea helps to reduce weight by stimulating the body’s thermogenesis process, which increases the expenditure of energy and the oxidization of fat in the body. Many compounds found in plants have this effect. The special thing about green tea is that it does not increase the heart rate, and is therefore believed to be safer than diet pills such as ephidrine that also work by stimulating thermogenesis.

A lot of people who are overweight have or are at risk of developing hypertension and other cardiovascular problems, so the fact that green tea does not put pressure on the heart makes it a good choice. Ephidrine is not usually recommended if you are in this group but green tea is considered a safe option. It means that you can gradually increase your exercise levels without increasing your risk of heart problems.

There are only two ways to lose weight: one way is by eating less (consuming fewer calories) and the other is by increasing expenditure of energy (using up more calories). Green tea works by increasing output and this can be by around 4%. Most scientists believe that this is caused by the high quantity of catechin that is in the tea and its extract.

Green tea has the added benefit of containing powerful antioxidants that may be beneficial to your health in many ways, strengthening the immune system and protecting against disease.

Keep in mind that green tea does contain caffeine so you should cut out coffee and other forms of tea while you are taking it. Decaffeinated green tea is not recommended because the chemical processes that are used to remove the caffeine may destroy the beneficial properties of the plant.

At the same time you will need to exercise control in what you eat. If you eat more to compensate for the calories that are burnt by the tea, you will not lose any weight. Keeping to the same calorific intake that you have now and taking green tea should result in gradual weight loss and better energy levels over a few weeks. You can of course increase the speed of this by reducing calorie consumption and/or increasing exercise.

Green tea is a simple, easy and inexpensive weight control aid that can easily be incorporated into any weight loss program. The choice of tea or extract offers something for everybody. Natural and safe, green tea weight loss should feature in your program if you want to keep the weight off permanently.

Start sipping your way to better health.

Tea has been used as a folk remedy for 5,000 years — to aid liver function, destroy typhoid germs, purify the body and preserve mental equilibrium — and now scientists are discovering it may have all those benefits and a whole lot more.

Studies presented this fall at the Fourth International Scientific Symposium on Tea and Human Health, hosted by the U.S. Department of Agriculture, showed that tea can be key to a healthful diet.

“As a nutrition scientist, I consider tea as a healthy choice for three reasons: It meets hydration needs, it has no calories and it’s really rich in phytonutrients (plantbased substances) that we know provide some human health benefits,” Jeffrey Blumberg, director of the Antioxidants Research Laboratory at Tufts University in Boston, said by telephone. “Tea has more of the catechins (phytochemicals that act as antioxidants) than any food I am aware of. It is far and away the biggest, richest best source of those phytonutrients.”

We asked Blumberg, cochairman of the symposium, about tea and health:

Question: Are green, black and oolong teas equally healthful?

Answer: I don’t know of any controlled trials comparing the different colors of tea, but all of them come from the same plant, the Camellia sinensis bush, and there is a huge overlap in what we are finding in different studies using different kinds of tea. Most of the observational studies use green tea in Japan and China and black tea in the U.S., India and Great Britain, but they all show the same results. One study looked at models of digestion and found that in the gut, bacteria and enzymes break down different kinds of tea so that when it gets to human tissue, they are all pretty much the same.

Q: Do you get the same health benefits from taking tea supplements?

A: There are not very many studies on tea supplements, yet the few that we have suggest they are mimicking some of the cardio and cancer benefits established in tea studies. You are going to get some of the same benefits from tea extracts, but they are not the same thing. I have a slight bias as a nutrition scientist. Mother Nature put a lot of different beneficial chemicals and compounds in tea, so why not take advantage of all of them? By definition, supplements are 80 percent to 90 percent concentrated polyphenol extracts, primarily EGCG, a powerful antioxidant, but as far as I know, theanine amino acid is not in extracts, and theanine is what helps you to focus your attention (on a task) or relax.

Q: How much do you need to drink to get the health benefits of tea?

A: From lots and lots of observational studies, it looks like four to five cups a day will put you in the highest 20 percent for protection against heart disease and stroke. Those who drink four cups or more consistently have the lowest risk of heart disease. There is definitely a dose/response relationship.

Q: Can you drink too much tea?

A: There is no evidence of harm in healthy human beings, within a tremendous range (of doses). Tea is caffeinated — it has about half as much caffeine as coffee — so if you are caffeine-sensitive, you might want to drink decaf, but there is no evidence to suggest any adverse consequence from tea consumption. (But a recent report showed that a woman who drank 2 gallons of strong tea every day for two years developed calcium deposits in her bones, Blumberg said.)

BENEFITS OF TEA

Various studies presented at the Fourth International Scientific Symposium on Tea and Human Health showed that tea can:

- Reduce risk of heart disease and stroke
- Lower cholesterol c Repair smoking-related DNA damage
- Prevent colon, rectal, pancreatic, stomach, prostate and oral cancers
- Lower risk of developing kidney stones
- Speed up metabolism
- Decrease body weight and fat
- Control blood sugar
- Lower the risk of osteoporosis

Other studies, conducted on animals, showed that tea may:
- Prevent and repair damage to brain cells
- Delay cognitive decline seen in Parkinson’s and Alzheimer’s disease
- Create a calmer, yet more alert state of mind

11/19/2007 - Black tea gel could provide double protection against UV radiation by absorbing UV rays and repairing DNA damage inside the skin.

Topical application of black tea gel significantly reduces skin redness after exposure to UV light, illustrating protective qualities against the radiation across the spectrum, according to researchers.

However protection peaks in the UVB range which accounts for most cases of sunburn. Protection against the deeply penetrating UVA rays is not so effective.

Natural alternative to sunscreen

The researchers applied an aqueous black tea gel to six subjects, in a three cm² patch on the forearm. The square (and a control patch of similar size but without the black tea gel) was then exposed to UV radiation whilst the rest of the arm was protected.

The study published in the International Journal of Cosmetic Science, reports that no visible erythema (skin reddening) was reported on any of the black tea gel sites throughout the study, whereas after 24 hours all six subjects showed some level of reddening in the control sites.

The authors conclude that black tea gel may protect from a broad range of UV radiation. Moreover they note that black tea gel can be liberally applied without concern over its toxicological safety.

Black tea absorbs UVB but not A

In addition, the researchers tested the absorption profile of the black tea extract and found that absorption peaked between 250 and 290 nm, suggesting the extract provides protection against rays in the UVB and C spectrum.

However, the absorption levels are less impressive for UVA rays, which are thought to play a role in skin aging and significantly contribute to skin cancer risk.

Increasing importance is being placed on UVA protection in sun care and in August of this year the FDA introduced a new labelling system, demanding for the first time that manufacturers put the UVA protection level provided by the product on the label.

Two fold protection

Black tea also exhibits skin repair properties due to its antioxidant components, according to the researchers, who reference a large body of literature that suggests black and green tea help repair UV induced skin damage.

The extract’s protective qualities are therefore twofold, conclude the authors: firstly it prevents the skin damage and sunburn by absorbing UV rays and secondly, it repairs UV induced damage to the skin cells.

The authors note that this two fold approach is not provided by conventional sunscreens that only block the UV rays by absorption.

In addition the team highlight that the extract is natural and low cost, with no known toxicological side effects.

Interest in natural alternatives to chemical sunscreens is high as the trend for organic and natural cosmetics gains momentum, and fears over the safety of chemicals in cosmetics become more widespread.

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.

“Although these results are preliminary, I think it’s encouraging that a big part of the puzzle comes down to simple chemistry,” said Mario Ferruzzi, assistant professor of food science at Purdue University and the study’s lead author.

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.

The study, published this month in Molecular Nutrition and Food Research, also found that soy, dairy and rice milk appeared to have moderate stabilizing effects. But Ferruzzi said the result is misleading; a chemical interaction between milk proteins and tea catechins apparently helps shelter the complex from degradation, a force likely overcome by enzymes within a healthy human digestive system.

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.

Although this study only examined green tea, Ferruzzi said he suspects that some of the results also could apply to black tea, which is produced by fermenting green tea. Many prefer black tea’s flavor, although it contains lower total levels of catechins.

Studies have shown catechins from the green tea plant, Camellia sinensis, are able to detoxify toxic chemicals, inhibit cancer cell activity and stimulate production of immune-strengthening enzymes. Finding methods to improve uptake of these catechins may, therefore, be important in improving health, part of the study’s goal, Ferruzzi said.

Ferruzzi currently is conducting an in vivo study, or study on a live organism, to quantify the ability of juices and vitamin C to increase levels of catechins in the intestines and bloodstream of animals and, by extension, in humans. He collaborates with the NIH-funded Purdue Botanicals Research Center on this project.

“This next study is designed to get us past the limitations imposed by our digestive model, which is really just a simple screening process that relies on preset physiology parameters,” he said. “Human digestion is a lot more complicated.”

To see if juices and vitamin C actually increase catechin absorption, researchers will have to find out if increased levels of intestinal catechins translate to higher levels of absorbed catechins in live animals and humans. They also will need to better document effects upon catechin metabolism in order to prove, for instance, that increased levels of absorbed catechins are not leveled off by metabolic factors, Ferruzzi said.

“This study tells us a lot of interesting things, but it raises many questions that have yet to be answered,” he said.

The study was funded by the National Institutes of Health.

*Different teas in different seasons

As the Chinese saying goes, “Green tea is for summer, black tea is for winter and oolong tea works all year around”, people choose different teas for the various seasons.

Spring is the season for flower teas, which can lift the spirit from drowsiness. Winter is a season for black tea whose hot nature helps protect the body against winter chills.

Summer is a season for green tea. The cooling nature of this tea can counter summer heat, boost the heart and eliminate toxins. For those who prefer icy cold drinks and those who have a weak stomach, oolong tea is recommended over green tea. Barley tea is also a nice choice in summer as it can eliminate pigment residues on the skin.

Autumn is a dry season so it’s good to pick qingcha tea, which is between black and green tea. Qingcha tea includes oolong and Tieguanyin, which can boost the secretion of saliva, improve the lungs and moisturize the skin.

*Different teas at different times of the day

In the morning Green tea: Rich in antioxidants and vitamin C, green tea can eliminate free radicals in the body and secrete anti-pressure hormones.

In the afternoon Chrysanthemum tea: It enhances the function of the liver and relieves the eyes. When combined with medlar or honey, chrysanthemum tea helps counter depression and anxiety.

In the evening Medlar tea: It’s rich in Beta-Carotene, vitamin B1, vitamin C, calcium and iron, as well as enhances the liver and kidney functions.

When working overtime Cassia seed tea: It’s good for the brain, liver, tendons and bones, as well as eyes. And if you suffer from constipation, have of a cup cassia seed tea after dinner. It’s guaranteed to be effective.

After a big meal Pu’er tea: Most teas boost the metabolism of fat, and Pu’er it is the leader in this area. There are some beneficial elements in the tea to help burn the fat reserves in the stomach.

*Different teas for different people

Office workers: Chrysanthemum tea and green tea
Sport lovers: Oolong tea and black tea
Those averse to sports: Green tea and flower teas
Those exposed to heavy air pollution: Green tea
Smokers and drinkers: Green tea
Meat lovers: Oolong tea
Those suffering constipation: Honey tea
Those wanting to lose fat: Oolong tea, Pu’er tea and green tea
Those with a weak spleen and stomach: Oolong tea and flower teas
Those hoping for longevity: Oolong tea and black tea