Green, Black or Oolong Tea
All “true” tea comes from the Camellia sinensis bush, but the way it’s processed determines whether the end product will be green, black or oolong tea.
Black Tea
To make black tea, the freshly picked tea leaf is deliberately exposed to the air, left on trays in the sun to wither and dry for 18-24 hours. Then the leaves are broken and allowed to ferment for a time, before being fired.
Oolong Tea
Making oolong tea is similar, although the withering and fermenting processes are shorter, resulting in a partially-fermented leaf.
Green Tea
But green tea leaf isn’t fermented at all – in fact, just the opposite! The tea leaves are steamed almost immediately after picking in order to stop the fermentation process, after which they are rolled and dried. So black tea is fermented, green tea is unfermented and oolong is somewhere in between.
To Ferment or Not to Ferment?
Whether or not the tea leaf is fermented has a great effect on the catechin content of the resulting tea. In green tea, the catechins make up about 15-30% of the dry weight of the leaves, compared to just 8-20% of oolong and a miserly 3-10% of black tea.
Why is the catechin content so much lower in black tea? The minute a tea leaf is plucked, an enzyme called polyphenol oxidase combines with oxygen and begins to change the catechins into compounds called theaflavins and thearubigens. This process is encouraged in the manufacture of black tea. Not only are the tea leaves left to wither in the sun for 18-24 hours, they are also twisted and broken to accelerate the process of converting catechins into theaflavins and thearubigens. These compounds are responsible for the distinctive taste, aroma and dark color of black tea. And while they do have some health benefits, they don’t have the same wide-ranging antioxidant and disease-fighting prowess as the catechins.
The Number One Rule in Green Tea Processing
Every green tea processor knows that, above all, they must protect the catechins from the effects of polyphenol oxidase -- to preserve the look, taste and health benefits of this amazing beverage. They do this by steaming or pan-firing the tea leaves just as soon as they are plucked, to inactivate the enzyme. This means the tea leaves must be rushed to the manufacturing plant as soon as they are picked, and care must be taken not to break or bruise the leaves in the process.
Then, once the leaves have been steamed, they can safely be rolled, twisted, dried and packaged without obliterating the catechins. Still, even after the leaves have been processed and packaged, the catechins in green tea can be destroyed if exposed to oxygen for too long. That’s why you should always keep your green tea in an airtight container, even if it comes in tea bag form. Remember: Oxygen is the catechins’ worst enemy.
Jul 29, 2008
Green, Black, Oolong Tea Differences
Does Bottled Green Tea Have Health Benefits
Does Bottled Green Tea Have Health Benefits
Have you ever wondered if bottled green tea has the same health benefits as freshly brewed green tea? Well, sorry to break the news to all of you bottled tea drinkers but in most cases, the answer appears to be no.
In December 2006, the U.S. Department of Agriculture made public its database on the flavonoid content of foods.1 (Flavonoids, a type of polyphenol, are a group of compounds found primarily in fruits and vegetables that act as powerful antioxidants. Green tea’s catechins are a sub-group of the flavonoids.) The USDA list, which includes the levels of catechins found in green tea that was prepared in different ways, is a real eye-opener for those who drink bottled tea for health reasons!
For example, the level of EGCg (green tea’s most potent catechin) in brewed loose-leaf tea was 77.81 mg per 100 grams of infusion. Decaffeinated green tea, however, had just one-third that amount, weighing in at 26.05 mg. But ready-to-drink green tea (the kind that comes in a can or a bottle) contained a minuscule 3.96 mg of EGCg, just 5 percent the amount found in freshly brewed green tea. And instant green tea was even worse, with a practically nonexistent .5mg EGCg!
Similar studies measuring the health-promoting compounds in green tea were done in 2005 by researchers at Oregon State University.2 They found that the polyphenol content and antioxidant activity in some bottled tea products were 10 to 100 times lower than those found in brewed tea!
Why does bottled (or canned) green tea have such low levels of catechins? A major reason is that the catechins are sensitive to heat and oxygen, making them easy to destroy during the processing, transporting and storing of bottled tea. Also, many bottled tea products are made from tea extracts, which have far fewer antioxidants to begin with than brewed tea. Then, to make matters worse, bottled tea products are often loaded with sugar or high fructose corn syrup which, besides being unhealthy and unnecessary, can contribute to catechin breakdown.
If you still want to drink bottled green tea, be sure to look for a high quality product made from brewed tea that contains no added sweeteners and has the polyphenol or catechin content listed on the label. Your best bet is a product that contains at least 75 mg polyphenols or 50 mg EGCg per cup. If you can’t find one, how about just settling for a nice bottle of water?
http://oregonstate.edu/dept/ncs/newsarch/2005/Oct05/teaprotection.htm
What Is Green Tea. Why Drink Green Tea
What Is Green Tea, Anyway?
First things first: The word “tea” is only used correctly when it refers to leaves taken from the Camellia sinensis bush. And that means that herbal teas really aren’t tea – only green, black and oolong tea are the “real thing.” That said, the way the Camellia sinensis leaves are processed will determine which of these three choices the end product becomes.
To make black tea, the freshly picked tea leaves must undergo a process called oxidation. Oxidation occurs when an enzyme in the tea leaf called polyphenol oxidase is brought into contact with the air. To do this, the leaves are left in the sun for 18-24 hours to wither and dry; then they’re broken up to encourage further oxidation. Steaming, pan-firing or roasting the leaves stops the oxidation process, after which they are rolled, twisted and dried. Making oolong tea involves a similar process, although the leaves are withered for a shorter period, which produces a partially-oxidized leaf. But for green tea, the leaf isn’t withered or broken at all – in fact, just the opposite! The tea leaves are steamed almost immediately after picking in order to stop the oxidation process, after which they are rolled and dried.
The health benefits of the resulting tea will largely be determined by whether or not the tea leaf has been oxidized. That’s because the fresh tea leaf contains large amounts of catechins (pronounced “CAT-i-kins”), which are the powerful disease fighters and potent antioxidants that give green tea its health-enhancing abilities. But when exposed to air and polyphenol oxidase, the catechins change into completely different compounds called theaflavins and thearubigens. The theaflavins and thearubigens, which give black tea its distinctive taste, aroma and dark color, do have some health benefits, but not the same wide-ranging antioxidant and disease-fighting prowess seen in the catechins.
So in green tea manufacturing, it’s extremely important to rush the freshly picked leaves from the field to the manufacturing plant, being careful not to break or bruise them. There, the leaves are steamed or pan-fired immediately to inactivate the polyphenol oxidase. Afterwards, it’s safe to roll, twist, dry and package the leaves without worrying about obliterating the catechins. Yet even after the manufacturing process has been completed, green tea catechins can be destroyed if exposed to oxygen for too long. That’s why you should always keep your green tea in an air-tight container, even if it’s already in tea bag form. Remember: oxygen is the catechins’ worst enemy!
Green Tea Help Bladder Inflammation
Green tea prevents bladder inflammation
Green tea might be useful as an herbal remedy to treat or prevent inflammatory bladder disease, according to researchers from the University of Pittsburgh School of Medicine. According to a study presented at the annual meeting of the American Urological Association (AUA) in Anaheim, California, two of the chemicals that naturally occur in green tea protected cultures of bladder cells from oxidative damage.
Researchers exposed cultures of both normal and cancerous bladder cells to epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), two varieties of a flavonoid group called catechins, for 23 hours. They then exposed the cell cultures to hydrogen peroxide, which is highly damaging to cells and may even kill them.
"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 researcher Michael B. Chancellor, a professor of urology and gynecology at the University of Pittsburgh School of Medicine.
"Although further studies are needed, these results indicate [that] herbal supplements from green tea could be a treatment option for various bladder conditions that are caused by injury or inflammation."
Catechins occur naturally in the leaves of the tea plant, and thus are present in green, black, white and Oolong tea. These chemicals compose, on average, approximately one-quarter of the dry weight of a fresh tea leaf -- although the exact content varies by individual plant, growing season and location.
Catechins are also found in chocolate, wine and certain fruits and vegetables. Previous studies have linked consumption of these chemicals to reductions in the risk of heart disease, cancer and diabetes.
According to the researchers, the doses of EGCG and ECG used in the Pittsburgh study are low enough to be achieved through dietary intake.
Approximately ten million people in the United States suffer from some form of bladder disease.
Green Tea May Help Keep Skin Cancer Away
A Cup of Green Tea Per Day May Help Keep Skin Cancer Away
While avoiding prolonged sun exposure, the regular and proper use of sunscreen, and regular examinations by a board-certified dermatologist are the main actions for preventing skin cancer, green tea may help as well.
“Green tea is reported to have antibacterial, antioxidant, and antitumor properties,” says Lawrence Osman, M.D., a board-certified dermatologist practicing in Los Angeles. Polyphenolic antioxidants are derived from the extracts of green tea. Also, the most widely studied component of green tea, (-)-epigallocatechin gallate, may work by inhibiting ultraviolet induced DNA damage. Inhibiting ultraviolet induced DNA damage may be important because many cases of skin cancer are directly related to ultraviolet exposure from the sun or tanning beds.
The constituents of green tea have already proven effective in helping to prevent skin cancer in the lab. Accordingly, drinking green tea, in addition to avoiding prolonged sun exposure, the regular and proper use of sunscreen, and regular examinations by a board-certified dermatologist, may help prevent skin cancer in life.
About Lawrence Osman, M.D., F.A.A.D. Dr. Lawrence Osman is a board-certified dermatologist practicing comprehensive medical, surgical, and cosmetic dermatology. He attended the Keck/USC School of Medicine and completed his dermatology training at the prestigious Roswell Park Cancer Institute. He has particular expertise in skin cancer surgery, laser surgery, and tumescent liposuction. He was voted as one of the best dermatologists by the readers of the Los Angeles Daily News. Dr. Osman may be contacted by calling (818) 885-0455 or visiting www.drosman.com.
Green Tea Can Ease Inflammation, Arthritis Pain
Green tea found to ease inflammation, arthritis pain
A new study has found that a compound in green tea may help people with rheumatoid arthritis avoid inflammation and joint damage. The study, conducted by University of Michigan researchers, was presented April 29 at the Experimental Biology 2007 conference in Washington, D.C.
"Our research is a very promising step in the search for therapies for the joint destruction experienced by people who have rheumatoid arthritis," said Salah-uddin Ahmed, Ph.D., the study's lead researcher. According to the Arthritis Foundation, more than two million Americans have rheumatoid arthritis.
Ahmed and his co-workers isolated cells called synovial fibroblasts, which form a lining of tissue that surrounds the joints. In cases of rheumatoid arthritis, this lining becomes inflamed, resulting in chronic pain and long-term joint damage.
The researchers cultured synovial fibroblasts from rheumatoid arthritis patients and then exposed the cells to epigallocatechin-3-gallate (EGCG), a naturally occurring compound in green tea. They found that EGCG blocked two potent molecules that cause the bone breakdown in rheumatoid arthritis-affected joints. Ahmed stated that the EGCG "significantly" blocked the harmful molecules. He and his co-workers observed that EGCG also blocked production prostaglandin E2, which causes joint inflammation.
Ahmed said that people might want to try drinking three or four 8-ounce cups of green tea per day. "Drink it continuously throughout the day," he said, to keep blood levels constant.
While this is the first study measuring the effects of EGCG on synovia fibroblasts, an earlier study demonstrated that polyphenols in green tea could prevent the onset of arthritis. In 1999, researchers at Case Western Reserve University's School of Medicine studied the effects of green tea on mice; the researchers found that mice given green tea were significantly less likely to develop arthritis than mice in a control group. The extract given to the mice was the equivalent of a human intake of four cups of green tea per day.
When sourcing green tea products, make a special effort to find organic green tea products. Many cheaper, imported green teas are contaminated with harmful fluoride.
Green Tea Can Reduce Ovarian and Colorectal Cancers
Green Tea Shown to Reduce Risk of Ovarian and Colorectal Cancers
Studies and Results
The March, 2008 issue of Cancer Epidemiology Biomarkers and Prevention, contains a study from the Fred Hutchinson Cancer Research Center in Seattle. In a population based study in Washington state, 781 women with epithelial ovarian cancer diagnosed between 2002 and 2005, and 1,263 controls completed self-administered questionnaires detailing consumption of caffeinated and non-caffeinated coffee, teas, and colas. They also completed in-person interviews regarding reproductive and hormonal exposures.
Researchers assessed risk associated with coffee, tea, and cola drinking and with total caffeine consumption using logistic regression to calculate odds ratios and confidence intervals. Results indicate that neither caffeinated nor decaffeinated coffees were associated with ovarian cancer risk. They also observed no association of total caffeine with risk using a combined index that summed intake from coffee, tea and carbonated soft drinks.
Among teas, neither herbal/decaffeinated nor black teas were associated with risk. However, women who reported drinking green teas had a 54% reduction in risk of ovarian cancer. Associations of green tea with risk were similar when invasive and borderline cases were considered separately and when Asian women were excluded from analysis.
In the second study from Cancer Biology and Therapy, researchers from the Fourth Military Medical University in Xi’an China, reported progress in identifying the underlying mechanism by which green tea possesses therapeutic cancer effects through induction of apoptosis (programmed cell death) in colorectal cancer. Two different lines of colorectal cancer cells were treated with different concentrations of green tea, which led to repression of cell proliferation and induction of apoptosis in both cell lines.
The researchers concluded that the p-53 up-regulated modulator gene plays a critical role in green tea induced apoptosis pathways in colorectal cancer cells. Their demonstration of this effect may be useful in the therapeutic target selection for p53 deficient colorectal cancer.
Additional Implications
The results of these studies suggest that green tea may also be a factor for inducing apoptosis in breast cells and endometrial cells, thereby acting as both a preventative and a factor in the cure for these cancers.
A further implication for the first study may be drawn from its conclusion that the administration of caffeine containing coffee, tea, and colas yielded no association with risk for ovarian cancers.
About Green Tea
According to Phyllis and James Balch in their book Prescription for Nutritional Healing, green tea contains polyphenols, including phytochemicals with antioxidant, antibacterial, antiviral, and other health enhancing properties. Epigalloacatechin gallate (EGCG) is a particular type of polyphenol in green tea that has shown in tests to be able to penetrate the body’s cells and shield DNA from the potent free radical, hydrogen peroxide.
In addition to protecting against cancers, green tea lowers cholesterol levels, and reduces the clotting tendency of blood. It shows promise as a weight-loss aid that can promote the burning of fat and the regulation of insulin levels and blood sugar.
Green tea is simply the unprocessed leaves of the tea plant, unlike black tea which is fermented. During processing, much of the polyphenols of black tea are lost.
In addition to brewing and drinking green tea, there are green tea supplements available. Some of these contain the whole plant, while others contain extracts. Whole plant supplements are usually preferable because they are backed by the integrity of the whole plant. Many green tea supplements are standardized to provide a quantifiable amount of EGCG, viewed as its most beneficial component.
About the author
Barbara is a school psychologist, a published author in the area of personal finance, a breast cancer survivor using "alternative" treatments, a born existentialist, and a student of nature and all things natural
Green Tea Compounds Prevent Memory Loss From Lack of Oxygen
Green Tea Compounds Prevent Memory Loss From Lack of Oxygen
People with sleep apnea, a disorder that affects more than 12 million people in the United States, literally stop breathing repeatedly during their sleep, sometimes for a minute or longer. With the most serious form, obstructive sleep apnea (OSA), this can happen hundreds of times during a single night and deprive the brain of oxygen.
The result? Possible brain damage causing memory problems. In fact, people with OSA are known to have increased markers of oxidative stress and exhibit changes in their brain tissue in areas involved in learning and memory.
But natural substances in green tea appear to stave off these OSA-caused cognitive deficits according to new research published in the second issue for May of the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine.
Scientists studied the effects of green tea polyphenols (GTP, for short) on rats who were intermittently deprived of oxygen in order to simulate the lack of oxygen, known as hypoxia, that humans with OSA experience. Chronic hypoxia in rats is known to produce similar neurological deficit patterns seen in humans with sleep apnea.
Previous research has shown that GTPs may reduce the risk of a variety of different diseases, most likely because they possess anti-oxidant properties and act as free radical scavengers. “OSA has been increasingly recognized as a serious and frequent health condition with potential long-term morbidities that include learning and psychological disabilities,” David Gozal, M.D., professor and director of Kosair Children’s Hospital Research Institute at the University of Louisville, said in a prepared release for the press. “A growing body of evidence suggests that the adverse neurobehavioral consequences imposed by hypoxia stem, at least in part, from oxidative stress and inflammatory signaling cascades.”
Dr. Gozal and his colleagues divided 106 male rats into two groups that underwent intermittent oxygen deprivation during the 12-hour “night” cycle for 2 weeks. One group received drinking water containing GTPs while the other group received plain drinking water.
Then the animals were tested for markers of inflammation and oxidative stress and their spatial learning and memory was measured by putting them through in a water “maze”. To get out of the water, the rats had to memorize the location of a hidden platform.
The rats who received the green tea-treated water clearly had the better memories and performed significantly better in the water maze than the rats that drank plain water. So the researchers concluded GTPs “may represent a potential interventional strategy for patients” with sleep-disordered breathing, according to Dr. Gozal, who headed the research team.
Using green tea instead of drugs prevents brain deficits due to hypoxia and could be an important aid to preserving the memories of millions of people suffering from sleep apnea. What’s more, green tea may well contain substances that offer hope for a variety of other brain-injuring diseases. “Recent studies have demonstrated the neuroprotective activity of GTP in animal models of neurodegenerative conditions such as Parkinson’s and Alzheimer’s disease,” Dr. Gozal wrote.
About the author
Sherry Baker is a widely published writer whose work has appeared in Newsweek, Health, the Atlanta Journal and Constitution, Yoga Journal, Optometry, Atlanta, Arthritis Today, Natural Healing Newsletter, OMNI, UCLA’s "Healthy Years" newsletter, Mount Sinai School of Medicine’s "Focus on Health Aging" newsletter, the Cleveland Clinic’s "Men’s Health Advisor" newsletter and many others.
