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The Tea House Times, Tea Health Guide

written by Daniel Gastelu, MS, MFS & Gail Gastelu

*All matters pertaining to your health should be supervised; consult your physician.*

ARTICLE

ABOUT THE AUTHORS

REFERENCE LIST

Tea (Camellia Sinensis) refers to Black, Green, and Oolong teas.  The teas differ by levels of fermentation processing.  Black is fully fermented (oxidized), Oolong is partially fermented, and Green is unfermented.  The Health Properties are similar due to similar bioactive health substances, like bioflavonoids, for example..  This page is a sampling of our Tea Health Guide.  The Tea Health Guide is written to provide quality information to the tea trade and consumers.

The following offers a scientific view of the health properties of Green Tea with some comparisons to Black Tea.  If you are a registered user of our website, you may log in and download the full version of our Tea Health Guide.

 This is copyrighted material and may not be reproduced by or for any means electronic or print.  Scientific references follow the article.

GREEN TEA

Green Tea -- a bioflavonoid-containing plant product - has been enjoyed as a hot beverage and an herbal remedy in China and Japan for thousands of year.  Recently, researchers have investigated green tea's healing properties and have discovered some interesting health benefits which include protection against certain infections; improved cardiovascular health; better dental hygiene; and protection from developing some types of cancer.

What exactly is Green Tea?

There are many different types of teas available these days.  Some are sold as herbal teas to distinguish them from black tea.  Green tea and regular tea come from the same plant - the Camellia sinensis shrub, which is native to Asia.  The leaves of Camellia sinensis are dried and cured in different ways to yield different types of tea.

Black varieties of tea, which are very popular in European countries and the United States, are prepared by processing, fermenting, and drying the tea leaves.  Green tea does not undergo fermentation.  Instead, the leaves are steamed, dried, and ready for use.  The steaming inactivates enzymes present in the tea leaves that can slowly break down the bioflavonoids.  Therefore, the green tea process preserves much of the beneficial nutrient content found in the fresh tea leaves.  The black tea varieties undergo chemical changes during the fermentation process, destroying most of the bioflavonoid content.

Does Green Tea contain caffeine?

Green tea does contain caffeine, but only roughly half as much as a cup of coffee or cola soft drink.  Specifically, a 6-ounce cup of green tea can contain 15 to 60 mg of caffeine.  There are decaffeinated green tea beverages and supplements available for people who want to avoid caffeine intake while experiencing the health benefits.

What are the Health Benefits of Green Tea?

Based on experimental studies and research conducted on green-tea consumption in human populations, some of the major beneficial effects of green tea include a reduced risk of many diseases such as heart disease; a reduction of dental problems; a reduced cancer risk, especially gastrointestinal cancer; the maintenance of healthy cholesterol levels; and anti-hypertensive effects.

What effect does green tea have on gastric cancer?

Japanese researchers documented a reduced risk of gastric cancers in populations drinking several cups of green tea per day.  According to vital health statistics, the death rate from cancer in both men and women in the Shizuoka region of Japan was found to be much lower than the national average.  This epidemiological study led researchers to conduct animal experiments to see if feeding green tea leaves to mice would suppress cancer cell growth.  They found that tumor growth in experimental mice fed green tea was indeed suppressed.  These results led researchers to take a closer look at the dynamics of green tea in reducing the risk of gastric cancers.  They explored which components of green tea were causing the reduction, and what other health effects green tea has on people.

In 1998, in the Japanese Journal of Cancer Research, researcher Suminori Kono and coworkers reported their work on the relationship of gastric cancer and diet in the Northern Kyushu region of Japan.  Their research supported the findings of other researchers: A decreased risk of gastric cancer was observed among those people with high green-tea consumption - ten or more cups a day.

How does Green Tea produce this anti-gastric cancer effect?

One way researchers believe that green tea reduces the risk of gastric cancer is that the bioflavonoids it contains has the ability to inhibit the activity of a mutagen-causing chemical called N-methyl-nitro-N-nitroguanidine.  In laboratory studies, this chemical has been shown to cause stomach cancer in animals.  Upon investigation, researchers determined that the major group of bioflavonoids primarily responsible for this protective action against gastric cancer is the catechins.  It's important to note, however, that the other bioflavonoids present in green tea also contribute to green tea's health benefits.  Usually, all the phytonutrients contained in any plant work together for maximum benefit.  This is known as synergistic.  It means that while certain activities of individual types of bioflavonoids or other phytonutrients can be determined, they seem to work better in the body when the entire phytonutrient group is present.

In 1992, Dr. Hans Stich reported his research findings in Preventive Medicine Journal, supporting the notion that the phytonutrients in green tea have chemoprotective effects, or offer protection against cancer-causing chemicals in the digestive system by inhibiting the formation or action of carcinogens present in the diet.  He found that green tea inhibited the formation of mutagenic nitrosamine products, which are suspected of causing gastric cancers.  Their inhibition can be beneficial, possibly reducing the risk of gastric cancers.

What about the cardiovascular benefits associated with drinking green tea?

There is some evidence that consumption of green tea can reduce the risk of cardiovascular diseases, such as heart attack and stroke.  This can be accomplished by keeping the levels of cholesterol in the blood within a normal range, promoting good blood flow, and from reduction of oxidation of LDL cholesterol.

Dr. Suminori Kono conducted a study on 1,306 men who drank nine or more cups of green tea daily.  He found them to have lower total cholesterol levels than non-green tea drinkers.  He further determined that increased consumption of green tea raises the so-called "good" high-density lipoprotein cholesterol (HDL), while lowering the so-called "bad" low-density lipoprotein cholesterol (LDL) and the very-low-density lipoprotein cholesterol (VLDL).

Other studies on animals and humans confirm these cardiovascular health benefits.  In particular, one study conducted on adult males and females consuming 500 mg of green tea catechins - equivalent to five cups of normal green tea brew - reported the following results:  lower blood pressure; increased HDL-cholesterol; and an improvement in bowel movements, promoting regularity.  Finally, a health survey conducted by Yoshikazu Sato and coworkers reported that among the 9,510 non-alcohol drinking, non-smoking women over forty years of age, the incidence of stroke and cerebral hemorrhage was significantly lower among those women who drank five or more cups of green tea a day.

What other health benefits does green tea have?

Due to the naturally occurring amount of fluoride in green tea, as well as the anti-bacterial action of its tannins, studies on animals have confirmed the dental-caries-inhibiting effect of green tea.  Thus, green tea may be used as a preventative of dental cavities.  Other benefits of drinking green tea before, during, and after meals includes antibacterial action, antioxidant effects, reduction of blood-glucose levels, as well as the anti-gastric cancer effects mentioned previously.

Researchers believe that the glucose-suppressing effect of green tea may benefit people on weight management programs and may be useful in treating or even preventing diabetes.  Topping all of these health benefits is the research conducted by Shoichi Sadakata and coworkers who examined the longevity effects experienced among female practitioners of chanoyu-Japan's traditional tea ceremony.  The 3,380 female practitioners of chanoyu were followed over an eight year period.  Sadakata found that the women who drank green tea had a lesser risk of death from all causes than compared to the population norm.

What's the best way to take green tea in order to get all these health benefits?

In general, people benefit most from drinking some green tea and taking supplements containing green-tea extracts.  When selecting dietary supplements, look for brands with green-tea extracts standardized to 25-percent or more polyphenols.  As part of a total dietary supplement plan, green-tea extract intake of 50 mg or higher will be beneficial, with amounts of 300 to 500 mg yielding therapeutic results.  Take green tea supplements before or with your meals and enjoy a cup of green tea often, in particular with meals.

*All matters pertaining to your health should be supervised; consult your physician.*

 

ABOUT THE AUTHORS:

Tea Health Guide Published by Supplementfacts Int'l and written by:

Daniel Gastelu, MS, MFS; a health, fitness, and nutrition expert and author.

 Gail Gastelu; founder, publisher, and editor of The Tea House Times and various special editions.

 

More about the author, Daniel Gastelu:

Daniel Gastelu, M.S., MFS is a health, fitness and nutrition expert and author. He currently serves as President of SUPPLEMENTFACTS International LLC, and Director of Nutritional Sciences of the International Sports Sciences Association.  Early in his career, Mr. Gastelu taught science courses at Rutgers University for the Department of Botany.  He is an avid tea drinker.

Some of Mr. Gastelu’s books include the following:

Gastelu, D., Red Rice Yeast, 2001, Health Issues Publications.

Gastelu, D., SAMe, 2001, Health Issues Publications.

Gastelu, D., The Complete Nutritional Supplements Buyer’s Guide, 2000, Random House, Inc.

Gastelu, D., All about Sports Nutrition, 2000, Avery Publishing Group.

Gastelu D., All About Bioflavonoids, 2000, Avery Publishing Group.

Gastelu, D., All About Carnitine, 2000, Avery Publishing Group.

Gastelu, D. and Hatfield, F. C., Weight Control, Fitness, and Performance Nutrition: The Complete Guide, 1999, International Sports Sciences Association.  Expanded and updated Specialist in Performance Nutrition course book.

Gastelu, D. and Hatfield, F. C., Dynamic Nutrition For Maximum Performance, 1997, Avery Publishing Group.

Gastelu, D. and Hatfield, F. C.,  Performance Nutrition: The Complete Guide. 1995, International Sports Sciences Association, Specialist in Performance Nutrition course book.

Burke, E. and Gastelu, D.,  Avery’s Sports Nutrition Almanac. 1999, Avery Publishing Group.

Weider, Ben and Weider, J. with Gastelu, D., The Edge: The Weider Guide to Ultimate Strength, Speed and Stamina, 2002, Avery Publishing Group.

 

TEA HEALTH GUIDE REFERENCE LIST

 

Ahmad N, Feyes DK, Nieminen AL, et al. “Green tea constituent epigallacatechin-3-gallate and induction of apoptosis and cell cycle arrest in human carcinoma cells,” J Natl Cancer Inst 1997;89:1881-1886.

 

Dulloo AG, Seydoux J, Girardier L, et al. “Green tea and thermogenesis: interactions between catechin-polyphe­nols, caffeine, and sympathetic activity,” Int J Obes Relat Metab Disord 2000;24:252-258.

 

Dulloo AG, Duret C, Rohrer D, et al. “Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans,” Am J Clin Nutrition 1999;70:1040-1045.

 

Erba D, Riso P, Colombo A, Testolin G. “Supplementation of Jurkat T cells with green tea extract decreases oxidative damage due to iron treatment,” J Nutr 1999;129:2130-2134.

 

Goto K, Kanaya S, Nishikawa T, et al. “Green tea catechins improve gut flora,”  Ann Long-Term Care 1998;6:1-7.

 

Graham HN. “Green tea composition, consumption, and polyphenol chemistry,” Prev Med 1992;21:334-350.

 

Imai, K, and K Nakachi, "Cross sectional study of effects of drinking green tea on cardiovascular and liver diseases," British Medical Journal 310, 18 March (1995): 693-696.

 

Imai K, Suga K, Nakachi K. "Cancer-preventative effects of drinking tea among a Japanese population,” Prev Med 1997;26:769-775.

 

Katiyar SK, Matsui MS, Elmets CA, Mukhtar H. “Polyphenolic antioxidant (-)-epigallocatechin-3-gallate from green tea reduces UVB-induced inflammatory responses and infiltration of leukocytes in human skin,” Photochem Photobiol 1999;69:148-153.

 

Katiyar SK, Mukhtar H. “Tea antioxidants in cancer chemoprevention,” J Cell Biochem 1997;27:S59-S67.

 

Kono, Suminori, et al., "A case-control study of gastric cancer and diet in Northern Kyushu, Japan," Japanese Journal of Cancer Research 79 (1988): 1067-1074.

 

Kono, Suminori, et al., "Green tea consumption and serum lipid profiles: a cross-sectional study in northern Kyushu, Japan," Preventative Medicine 21 (1992): 526-531.

 

Lee IP, Kim YH, Kang MH, et al. “Chemopreventative effect of green tea (Camellia sinensis) against cigarette smoke-induced mutations (SCE) in humans,” J Cell Biochem 1997;27:S68-S75.

 

Sato, Y, et al., "Possible contribution of green tea drinking habits to the prevention of stroke," Tohoku Journal of Experimental Medicine 157 (1989): 337-343.

 

Serafini M, Ghiselli A, Ferro-Luzzi A. “In vivo antioxidant effect of green and black tea in man,” Eur J Clin Nutr 1996;50:28-32.

 

Snow, J, "Herbal Monograph: Camellia sinensis," The Protocol Journal of Botanical Medicine, Autumn (1995): 47-51.

 

Wang, Zhi Y, et al., "Antimutagenic activity of green tea polyphenols," Mutation Research 223 (1989): 273-285.

 

You S. “Study on feasibility of Chinese green tea polyphenols (CTP) for preventing dental caries,” Chung Hua Kou Hsueh Tsa Chih 1993;28:197-199.

 

Zhao, B, et al., "Scavenging effect of extracts of green tea and natural antioxidants on active oxygen radicals," Cell Biophysics Volume 14 (1989): 175-185.

 

Zhao JF, Zhang YJ, Jin XH, et al. “Green tea protects against psoralen plus ultraviolet A-induced photochemical damage to skin,” J Invest Dermatol 1999;113:1070-1075.

 

If you are a registered user of our website, you may log in and download the full version of our Tea Health Guide.  

 

*All matters pertaining to your health should be supervised; consult your physician.* See reader notice below.

The information here is not intended for use as a substitute for consultation with a qualified medical practitioner, medical treatment or medical advice. If you have symptoms of any illness, or a known disease, it is essential that you see your doctor without delay. You are unique, and your diagnosis and treatment must be individualized for you by your own doctor. You are encouraged to work closely with your doctor and other health care professionals to achieve optimum health and visit them on a regular basis to monitor your health. The Tea House Times, the Author(s), and their affiliates, successors, assigns and their respective officers, directors, agents and employees will not accept responsibility for injury, loss, or damage occasioned to any person acting or refraining to act as a result of material read or provided here, whether or not such injury, loss, or damage is due in any way to any negligent act or omission, breach of duty, or default.


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