Drink to your health

DR. T.S. SARAVANAN

Catechins in green tea are novel biocompounds with multifarious health benefits.

PHOTO: A. ROY CHOWDHURY

Protective effects: Preparing green tea in Japan.

GREEN tea is a perennial shrub belonging to the family Camellia, native to the mountainous southwest of China. Teas are usually categorized into two types: Chinese (Variety Sinensis) and Assam (Variety Assamica). All teas come from leaves that are picked and processed from the same type of tree. The specific method of processing differentiates the various types of teas into green, black, and oolong tea.

In preparing green tea, the leaves are dried but not fermented. Commercially prepared green tea extracts contain 60 per cent polyphenols.

Good for health

There are four primary polyphenols in green tea and they are often collectively referred to as catechins. As powerful antioxidants, catechins have been shown in recent studies to fight viruses, slow aging, antiproliferative effect on cancer cells and also have other beneficial effect on health.

Clinical tests have shown that catechins destroy free radicals and have far-reaching positive effects on the entire body. The free radicals are highly reactive molecules that can damage the body at the cellular level leaving the body susceptible to cancer, heart disease and many other degenerative diseases.

Recent research findings suggest that green tea confers protective effects against many cancers.

The incidence of prostate cancer, for example, is the lowest in China and Japan, countries with high green tea consumption. Risk of oesophageal cancer was reduced by 60 per cent in those who consume two to three cups of green tea daily in China. A prospective cohort study of 8,552 Japanese found a significant inverse relationship between green tea consumption and cancer incidence.

Females consuming more than 10 cups of green tea daily had the most notable protection, compared with those consuming less than three cups per day.

Better outcomes

Green tea consumption has also been associated with a better outcome in some with breast cancer. Higher intake of green tea (mean: eight cups a day) is associated with a significantly reduced recurrence rate and a longer disease-free period, particularly among pre-menopausal women with histologically classified stage I and II breast Cancer. Among the specific green tea related benefits noted in patients were decreased numbers of axillary lymph node metastases.

Further, Epigallocaechin-3-gallate (EGCG) especially has shown marked anti-cancer effects against breast, colon, prostate, pancreatic, skin, bladder, lung, stomach, ovarian, leukaemia and liver cancer.

ECGC has also been shown to induce apoptosis in several of these cancer types while leaving normal cells unaffected and also shown to inhibit urokinase, a proteolytic enzyme often required for cancer growth, angiogenesis and androgen activity in prostate cell line. Very recently ECGC has been shown to be more effectively suppress the growth of prostate cancer and epithelial ovarian cancer cell lines derived from tumours of patients with different stage of disease.

Heart and cholestrol

The incidence of cardiovascular disease in China is about 80 per cent lower than in developed countries. This has been associated with the high consumption of green tea.

Numerous epidemiological studies have also associated high intake of green tea with decreased risk of atherogenesis in Japan.

In nitro and animal studies have shown that green tea and its catechins, especially EGCG, can help prevent oxidation of LDL-cholesterol. Recently, a human study demonstrated that EGCG inhibits phospholipids hydroperoxidation in plasma.

Mixed results have been reported on the ability of green tea to significantly reduce LDL-cholesterol oxidation in humans in that daily consumption of seven to eight cups of green tea might reduce LDL-cholesterol oxidation to an extent reduce the risk of cardiovascular disease.

In Japan, researchers have found that green tea may protect the ageing brain, as regular consumption means lesser risk of mental decline due to age.

Further, a study of 1003 70-year-old adults revealed that those who drank two or more cups a day were about half as likely to show cognitive impairment as those who drank three cups or less each week. Men and women who averaged one cup per day fell somewhere in between.

Anti-inflammatory

In addition, catechins have exhibited a variety of anti-inflammatory effects, raising hopes that they might be helpful in treating some forms of arthritis, dermatosis, gout and other inflammatory conditions.

Green tea also has thermogenic properties and promotes fat oxidation. There is in vitro evidence that green tea and its catechins have some antiviral and other antimicrobial activities.

Recently various green tea catechins were shown to inhibit extracellular release of vero toxin from enterohemorrhagic E. coli.

The writer has carried out research on green tea catechins at John Wayne Cancer Institute at Santa Monica, Los Angeles, California.

Tea fights cataracts, boosts insulin activity

November 21, 2005

New research in animals suggests that tea may be a simple, inexpensive means of preventing diabetes and its ensuing complications, including cataracts. Researchers fed green and black tea to diabetic rats for three months and then monitored the chemical composition of the rats' blood and eye lenses.

At levels that would be equivalent to less than five cups of tea per day for a human, both teas significantly inhibited cataract formation relative to a control group which did not get tea, according to Joe Vinson, Ph.D., a chemist at the University of Scranton (Penn.) and lead author of the paper.

Another study on tea, done by researchers from the U.S. Department of Agriculture, found that the popular beverage may increase insulin activity.

Using black, green and oolong teas, the scientists found that tea increased insulin activity by about 15-fold in tests using fat cells obtain from rats.

The effect was primarily due to epigallocatechin gallate, an active compound found in tea, says study leader Richard A. Anderson, Ph.D., of the USDA's Agricultural Research Service in Beltsville, Md.

The American Chemical Society is a nonprofit organization, chartered by the U.S. Congress, with a multidisciplinary membership of more than 158,000 chemists and chemical engineers. It publishes numerous scientific journals and databases, convenes major research conferences and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.

Michael Bernstein
m_bernstein@acs.org
American Chemical Society
http://www.acs.org

Green Tea Consumption and Mortality Due to Cardiovascular Disease, Cancer, and All Causes in Japan

The Ohsaki Study

Shinichi Kuriyama, MD, PhD; Taichi Shimazu, MD; Kaori Ohmori, MD, PhD; Nobutaka Kikuchi, MD; Naoki Nakaya, PhD; Yoshikazu Nishino, MD, PhD; Yoshitaka Tsubono, MD, PhD; Ichiro Tsuji, MD, PhD

JAMA. 2006;296:1255-1265.

Context Green tea polyphenols have been extensively studied as cardiovascular disease and cancer chemopreventive agents in vitro and in animal studies. However, the effects of green tea consumption in humans remain unclear.

Objective To investigate the associations between green tea consumption and all-cause and cause-specific mortality.

Design, Setting, and Participants The Ohsaki National Health Insurance Cohort Study, a population-based, prospective cohort study initiated in 1994 among 40 530 Japanese adults aged 40 to 79 years without history of stroke, coronary heart disease, or cancer at baseline. Participants were followed up for up to 11 years (1995-2005) for all-cause mortality and for up to 7 years (1995-2001) for cause-specific mortality.

Main Outcome Measures Mortality due to cardiovascular disease, cancer, and all causes.

Results Over 11 years of follow-up (follow-up rate, 86.1%), 4209 participants died, and over 7 years of follow-up (follow-up rate, 89.6%), 892 participants died of cardiovascular disease and 1134 participants died of cancer. Green tea consumption was inversely associated with mortality due to all causes and due to cardiovascular disease. The inverse association with all-cause mortality was stronger in women (P = .03 for interaction with sex). In men, the multivariate hazard ratios of mortality due to all causes associated with different green tea consumption frequencies were 1.00 (reference) for less than 1 cup/d, 0.93 (95% confidence interval [CI], 0.83-1.05) for 1 to 2 cups/d, 0.95 (95% CI, 0.85-1.06) for 3 to 4 cups/d, and 0.88 (95% CI, 0.79-0.98) for 5 or more cups/d, respectively (P = .03 for trend). The corresponding data for women were 1.00, 0.98 (95% CI, 0.84-1.15), 0.82 (95% CI, 0.70-0.95), and 0.77 (95% CI, 0.67-0.89), respectively (P<.001 for trend). The inverse association with cardiovascular disease mortality was stronger than that with all-cause mortality. This inverse association was also stronger in women (P = .08 for interaction with sex). In women, the multivariate hazard ratios of cardiovascular disease mortality across increasing green tea consumption categories were 1.00, 0.84 (95% CI, 0.63-1.12), 0.69 (95% CI, 0.52-0.93), and 0.69 (95% CI, 0.53-0.90), respectively (P = .004 for trend). Among the types of cardiovascular disease mortality, the strongest inverse association was observed for stroke mortality. In contrast, the hazard ratios of cancer mortality were not significantly different from 1.00 in all green tea categories compared with the lowest-consumption category.

Conclusion Green tea consumption is associated with reduced mortality due to all causes and due to cardiovascular disease but not with reduced mortality due to cancer.

Author Affiliations: Division of Epidemiology, Department of Public Health and Forensic Medicine, Tohoku University Graduate School of Medicine (Drs Kuriyama, Shimazu, Ohmori, Kikuchi, Nakaya, and Tsuji), and Division of Health Policy, Tohoku University School of Public Policy (Dr Tsubono), Sendai, Japan; Division of Epidemiology, Miyagi Cancer Center Research Institute, Natori, Japan (Dr Nishino).

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Green tea helps fight the flu

Roman Bystrianyk, "Green tea helps fight the flu", Health Sentinel, November 29, 2005,

Each year there is a mounting fear as the flu season approaches. With much of the attention given to the avian flu this year, the level of anxiety has increased in many people. With these concerns there is an interest in finding alternatives that can help fight the flu.

Several studies show that green tea – in particular chemicals called polyphenols – decrease the infectivity of the influenza virus. A study conducted at Pace University indicated that green tea extracts and polyphenols have an adverse effect on bacteria that cause strep throat and other infections. Milton Schiffenbauer, PhD, a microbiologist and biology professor at Pace University in New York City, stated in a news release that, “Our research shows tea extracts can destroy the organism that causes disease. If we can stimulate the immune system and at the same time we are destroying the organisms then it makes sense to drink more tea.”

Green tea is produced from the leaves of an evergreen plant called Camellia sinensis. The major active ingredient in green tea is believed to be the polyphenol compounds called catechins. These key compounds include EGCG, EGC, and ECG.

A study in the August 2005 journal Antiviral Research, examines these compounds against three currently circulating influenza viruses. The authors performed a number of experiments to examine the effects of green tea on these flu strains.

They found that these compounds were effective in reducing the plaque forming capabilities of the viruses. A plaque is produced when a virus infects a cell, replicates, and then kills that cell. EGCG and ECG at 50 μM (micromolar) inhibited more than 50% of the plaque forming ability of the influenza viruses. However, when all the polyphenols were combined the mixture reduced the plaque forming by over 90% and in the case of one flu strain (A/Chile/1/83 – H1N1) by nearly 100%.

Other experiments showed that the greater the concentration of green tea polyphenols the more of the flu virus was inhibited. “The results suggest that the antiviral effect is exerted not only in the initially infecting viruses but newly propagated viruses as well.”

After drinking 1 cup of tea, the maximum blood concentration of EGCG in humans reaches 60 micromoles in adults weighing 60 kg (132 pounds). Some authors recommend as many as 10 cups of green tea per day to achieve green tea’s optimal benefits, although the study authors caution that this study was done outside the human body and should be interpreted with some caution.

The author’s emphasize that the “total tea extract” was much more effective than any single of the green tea polyphenols that were tested in isolation. They note that, “dietary uptake of tea would be beneficial for direct intervention of influenza virus infection.”

SOURCE: Antiviral Research, August 2005

Tea Terms

Assam - Tea harvested originally in Assam, India (used in Irish breakfast teas). It is actually a different varietal of tea, Camellia Assamus.

Black Tea - These teas are fully fermented or oxidized. Darjeeling, Assam, are included in this type of tea. The longer the leaves are fermented, the darker they become, which is why black tea is darker than oolong, and oolong is darker than green tea.

Brick Tea - Green tea steamed, dried, then pulverized into brick form.

Camellia Sinensis - The Tea Plant. The differences between the over three thousand types of tea result from variations in the processing of the leaves after they are harvested. Tea is an evergreen shrub which grows in tropical or sub-tropical climates. See Green Tea, Black Tea, Oolong and White Tea. Assam is actually Camellia Assamus.

Ceylon - Black Tea harvested in Sri Lanka, which used to be called Ceylon.

Cha - The way to say "Tea" in China.

Chanoyu - Japanese Tea Ceremony with its roots in Zen Buddhism.

Darjeeling - Tea harvested in the Darjeeling region of India.

Dragonwell Tea - Green Tea from China, which is noted for its cooling effect in hot weather.

Genmaicha - also called "popcorn tea", this is Japanese Green sencha leaves blended with roasted rice, which sometimes pops during shipment, and resembles popcorn.

Green Tea - These leaves are light green and are not fermented. The supposed benefits of Green Tea include a longer life and recent studies have associated this tea with anti-carcinogens. There are two types of green tea, Steamed and Kiln-roasted. Steaming the tea takes out its bitter taste.

Gunpowder Tea - Green Tea from China that is rolled into fine pellets that "pop" when infused. Morrocans use this for mint tea.

Herbal Tea - Not considered Tea by purists, but a tea nontheless. Jasmine, Chamomile and Mint are some popular varieties. Berries, herbs and spices are included in Herbal teas.

Hojicha - Green tea that is left flat (not rolled) and oven roasted after manufacture.

Infusion - simply put, herbal tea, called Tisane in France.

Keemun - Black Tea harvested in the Anwhei Province of China, appreciated because, unlike other teas, it actually gets better with age. (Hao Ya is the finest grade of this type of tea.)

Kung Fu Tea - Kung Fu is a Chinese phrase for anything that requires special skills. Mostly known as Kung Fu (cantonese for Gong Fu) martial arts, but can also apply to skillful tea preparation (kung fu style) or tea processing without breaking leaves.

Lapsang Souchong - Black Tea harvested in the Fujian Province of China. It had a smoky flavor, from drying leaves over pine fires.

Luk Yu - (or Lu Yu, depending on who's translating) The Tang dynasty writer and poet who wrote the Cha Jing (The Tea Classic) which summarized the entire tea industry at the time from cultivation to enjoyment.

Matcha - Literally, "Liquid Jade" in Japanese, this is a finely ground green tea used in Chanoyu.

Nilgiri - Black Tea harvested in Southern India

Oolong - Partially fermented tea. A cross between black and green tea. They are mainly produced in Taiwan and the Fuchien and Chianghsi provinces of China. Formosa Oolong (Oolong from Taiwan) is considered the best.

Pekoe - (pronounced Peck-o) from Pek Ho which is Cantonese for Bai Hau, meaning the bud of the tea plant after processing. Pekoe, and Orange Pekoe have come to mean the name of any whole leaf black tea that is flavored, and have nothing to do with the bud anymore.

Pu-Erh - Tea harvested in the Yunnan province of China, the leaves are large, and are used to make black, green and oolong teas. Valued more for its medicinal value than it's taste, it is often blended with chrysanthemum.

Red Tea - The same thing as Black Tea, called so in China, because of its reddish color when brewed.

White Tea - A rare tea found in China. These amber leaves are not fermented, and are comprised only of the tips of the tea plant. They stand up on end in the cup when served. Considered a delicacy. Pai Mu Tan is a type of white tea.

Yixing teapot - This unglazed pot comes from the purple clay in the Yixing region of China, and is touted for its flavor and ability to conserve heat. It is said if one uses this porous pot for many years, one can get a great pot of tea simply by adding water to an empty Yixing pot! (It remains the connoisseur's choice of material for making teapots.)

Yunnan - Black Tea harvested in the Yunnan Province of China, not to be confused with Pu-Erh. Yunnan Black is served complete with buds, to produce a golden color and flavor.

Matcha

I have finally tried Matcha (抹茶).

Matcha (抹茶) is a Japanese Green Tea that is stone ground into a fine powder. I was very surprised at the great taste of this tea and I am now making my fourth cup.

Matcha (抹茶) is used in the Japanese tea ceremony (cha-no-yu, chadō, or sadō 茶道) from around the 12th century, but here in the 21st century I will use it for a refreshing beverage!

What's Better for You: Coffee or Tea?

Studies Have Shown Coffee and Tea Have Several Health Benefits

June 27, 2006 — - When you reach for that mug in the morning, you may get more benefits than a jump-start to the day.

Daily cups of coffee have been linked to a reduced risk of Parkinson's disease, liver cancer, gallstones and type 2 diabetes. In addition, green tea and white tea have been touted for their health benefits.

"What's interesting really is for years we were beating up on coffee. … And now study after study is suggesting benefits," said "Good Morning America" medical contributor David Katz.

So given the choice between coffee and tea, what's the healthiest thing you can reach for in the morning?

You can find Katz's advice below. Full disclosure: He's a coffee drinker.

How Much to Have?
The maximum recommended amount of coffee is four 8-ounce cups a day, although it depends on the individual in terms of body size, among other factors. Because caffeine has been shown to raise blood pressure, you should limit your intake if you have any blood pressure abnormalities. More than four cups is never recommended.

Antioxidants
There is the strong suggestion that the antioxidants in tea -- whether it's black, green or white -- have health benefits. Antioxidants can prevent inflammation of the blood vessels, and it has been linked to reduced risk for cancer. In terms of antioxidants, white tea has the most, followed by green tea, black tea and coffee. Green and white teas are made from different parts of the tea leaves, but both are minimally processed, unlike black tea, which is fermented. It appears the process of fermentation reduces the antioxidants in the final product.

Caffeine
Caffeine is associated with enhanced alertness, increased productivity and concentration when you're driving, and enhanced athletic performances. In terms of caffeine, coffee has the most followed by black tea, green tea and white tea.

Tea Vs. Tea Beverages
Because the health benefits of tea has become more recognized by the public, some manufacturers are putting a small amount of it in a product, then adding ingredients that are bad for you, such as sugar. For instance, a Snapple Green Tea has 46 grams of sugar in it -- the equivalent of about 11 sugar cubes. That's more than twice as much sugar as you get in a Hershey chocolate bar, which as 22 grams of sugar. Just because the label says white tea doesn't make it a healthy drink.

"Our green teas provide consumers with functional benefits … and great taste," Snapple said in a statement on its product. "We offer a lime green tea in both a diet and regular version, giving consumers different choice and calorie options."

Coffee or Tea?
If you have a choice between coffee or tea, Katz says tea is better. If coffee is part of your morning routine, you have nothing to worry about.

Lychee Tea

Yesterday I bought some Lychee Tea from my favorite local (and only) tea shop. I am not much of a fan of flavored tea, but I thought I'd give this tea a try. The lychee fruit is some kind of tropical fruit in the soapberry family native from southern China.
I really did not care for the flavor of the tea, but I drink all of my teas unsweetened and I may try my next cup of Lychee Tea sweetened with some honey (if I sweeten my tea I usually use honey as my first try, then I'll try pure cane sugar next).

Silver Needle White Tea

This white tea I just bought from Adagio Teas is one of the better white teas I have had in a very long time. The infused color ot the tea is very light and the taste is kind of nutty with a very clean finish.

I have recently started to enjoy white tea because I have held back on buying white tea due to it's high price and needing to use twice the amount of regular black and green teas. But after finally breaking down to buy some white tea, I am now addicted to white teas.

Wild Cherry Black Tea

I am not much of a flavored tea drinker, but I do like the Wild Cherry tea from Upton Tea Imports. They use a good quality black tea and add real wild cherries to the tea for a natural flavoring.