Tea is the most widely consumed beverage in the world, second only to water. Green tea in particular has gained great popularity in recent years, largely due to the tremendous amount of research showing its ability to support the body’s natural defenses against problems such as arthritis, cancer, cardiovascular disease, diabetes, weight gain, and cognitive impairment.
The History and Mythology of Green Tea
Archeologists have found that people in China and India ate tea leaves steeped in boiling water as far back as 5,000 years ago. Green tea has been used in traditional Chinese and Indian medicine for centuries as a stimulant, diuretic, and astringent (to control bleeding and help wounds heal), and to support heart health. Additional uses of green tea have historically included treating flatulence, regulating body temperature, regulating blood sugar, promoting digestion, and improving mental processes.
There is a popular legend in India concerning the origins of the tea plant. It is said that when Prince Siddhartha Gautama, the founder of Buddhism, was traveling through China, he became frustrated at his inability to stay awake during meditation so he tore off his eyelids. They say that a tea plant sprouted from the spot where his eyelids fell, and the plant gave him the ability to stay awake, meditate and reach enlightenment.
Currently about 500,000 tons of green tea is produced each year throughout Asia and in parts of the Middle East and Africa. It is mostly consumed by people in Asia, the United States, Europe and some parts of North Africa.
There are three main varieties of tea – green, black and Oolong – that come from the leaves of the Camellia sinensis plant. To make green tea, the newly harvested leaves are immediately steamed to prevent fermentation and preserve the natural polyphenols. This process also preserves the green color of the leaves. When the leaves are allowed to partially ferment, they turn into Oolong tea; and when they fully ferment, they become black tea.
What's So Good About Green Tea?
Green tea contains high concentrations of polyphenols, called catechins, which have potent antioxidant properties. Antioxidants are essential to good health because they neutralize free radicals – harmful molecules that damage our cells and DNA, and increase vulnerability to numerous illnesses including heart disease and cancer.
Although there are six primary catechin compounds in green tea, epigallocatechin gallate (EGCG) is the most active and also the most studied. It is 100 times more effective in neutralizing free radicals than vitamin C and 25 times more powerful than vitamin E.
Green Tea and Natural Cancer Defense
Because significantly less cancer is found in Asian populations than in North American and European populations, and because the people in Asian countries tend to drink a lot more green tea, a great deal of research has been focused on the possible ways green tea might support the body’s natural defenses against cancer.
After studying green tea and cancer for 16 years, U.S. Veterans Affairs scientist Santosh Katiyar, PhD, MS, is convinced that green tea, because of its rich polyphenol content, is among the most potent tumor-inhibitors that nature provides.
In the laboratory, studies have shown that tea catechins act as powerful inhibitors of cancer growth by scavenging oxidants before cell injuries occur, reducing the incidence and size of chemically induced tumors, and inhibiting the growth of tumor cells.(1)
Following are a few examples of the conclusions from these studies:
• When female rats with breast cancer were given green tea extract, there was a 70% decrease in tumor weight, slower tumor development and less malignancy.(2)
• A 2007 study looking at the mechanisms by which EGCG inhibits breast cancer cells concluded that “green tea and EGCG offer attractive antitumorigenic agents that can be easily and safely incorporated into daily lives.”(3)
• A study of green tea's effect on breast cancer conducted at the Boston University School of Medicine concluded, “Although EGCG inhibits multiple cancer-inducing cellular programs, the fact that it profoundly improves the histology of the DMBA-induced tumors argues for its value in being incorporated into the diet for chemoprevention against environmental carcinogens.”(4)
• A Korean study looked at the chemopreventive effects of green tea against cigarette smoke-induced mutations called sister-chromatid exchange (SCE) that may contribute to tumor growth. Participants were divided into four groups: non-smokers, smokers, smokers drinking three cups of green tea a day, and smokers drinking three cups of coffee a day. After six months, the rate of SCE was significantly higher in both the smoking group and in the smokers who drank coffee, though the rate in the group of smokers who drank green tea was comparable to that of the non-smokers – implying that green tea can block the cigarette-induced increase in SCE.(5)
Note: Green tea should not be used if you are undergoing radiation treatment for cancer. Radiation kills tumor cells via oxidation and green tea has antioxidant qualities that could interfere with radiation therapy.
Green Tea and Cardiovascular Health
In a 2008 review of current scientific evidence relating to green tea's ability to support a healthy cardiovascular system, scientists reported that the more green tea people consumed, the lower their risk for cardiovascular disease.(6)
Here are the results from two other individual studies dealing with green tea and cardiovascular health:
• A 2009 study looked at the cardiovascular effects of short-term green tea consumption. Participants were asked to drink four cups of green tea per day for 14 days without altering any other part of their normal diet. At the end of the two weeks, the participants showed reductions in blood pressure, fasting total cholesterol, body fat and body weight. These results suggest that green tea may have a positive role in reducing cardiovascular risk factors.(7)
• A 2001 study conducted in Japan found that the tea catechin EGCG inhibited the oxidation of LDL cholesterol in vitro.(8) Since the oxidation of cholesterol is what causes it to become “sticky” and form plaque in the arterial walls, inhibiting its oxidation is an important factor in preventing cardiovascular problems.
Additional Health Benefits of Green Tea Demonstrated
Although the majority of green tea research seems to have focused on cancer and cardiovascular disease, there are also hundreds of other studies evaluating the benefits of consuming green tea for just about any health issue you can imagine - from asthma to genital warts, and from dental cavities to the common cold.
Following are a few samples of other areas of green tea research:
Diabetes Risk - In an interesting study done in 2004, researchers looked at glucose metabolism in both diabetic mice and healthy humans. They found that green tea promoted glucose metabolism in healthy humans and lowered blood glucose in diabetic mice. They concluded that the study “provides evidence that green tea has an antidiabetic effect.”(9)
Weight Control - Based on recent data from human studies indicating that green tea extracts may support body weight reduction by increasing thermogenesis and fat oxidation, a German study looked specifically at the effect of EGCG on weight loss. They found that EGCG “has the potential to increase fat oxidation in men and may thereby contribute to the anti-obesity effects of green tea.”(10)
Rheumatoid Arthritis - Investigators at the University of Maryland and Rutgers University examining the effects of green tea polyphenols on rheumatoid arthritis found that green tea significantly reduced the severity of the arthritis. They suggest that green tea affects arthritis by promoting positive changes in various arthritis-related immune responses.(11)
Cognitive Functioning - A 2006 study of 1,003 volunteers examined the association between green tea consumption and cognitive function in humans. Researchers concluded that a higher consumption of green tea is associated with a lower prevalence of cognitive impairment in humans.(12)
To Drink or To Supplement...
Is it better to drink your green tea or to take a green tea extract supplement? While drinking green tea is certainly good for you, there are a couple of reasons why supplementing with EGCG-rich green tea extract is better:
• Convenience. It would be difficult to drink the quantity of green tea needed each day to provide the recommended amounts of EGCG – often 10 cups a day or more. Or you could take a single veggie cap of ProHealth's Green Tea EGCG Extreme - the most potent green tea extract on the market today.
• 99.6% caffeine free. Even if you could drink the needed 10 cups a day or more of green tea, you would be getting a great deal of caffeine with it. The Green Tea EGCG Extreme supplement contains only a tiny amount of caffeine.
Green tea – studied extensively in humans, animals and laboratory tests – contains powerful antioxidants and has been shown to promote good health. Research continues as more and more specific health benefits are discovered each year.
1. Dufresne CJ, Farnworth ER. A review of latest research findings on the health promotion properties of tea. J. Nutri Biochem 2001; 12(7):404–421.
2. Kavanagh KT, et al (2001). Green tea extracts decrease carcinogen-induced mammary tumor burden in rats and rate of breast cancer cell proliferation in culture. J Cell Biochem, 82:387-398.
Full journal article: www.bu.edu/cms/www.bumc.bu.edu/whirc/files/PDF/Kavanaghetal.pdf
3. Belguise K, et al. Activation of FOXO3a by the green tea polyphenol epigallocatechin-3-gallate induces estrogen receptor a expression reversing invasive phenotype of breast cancer cells. Cancer Research 67, 5763-5770 (2007).
Full journal article: www.bumc.bu.edu/whirc/files/2008/11/belguise_canres.pdf
4. Belguise K, et al. Green tea polyphenols reverse cooperation between c-Rel and CK2 that induces the aryl hydrocarbon receptor, Slug and an invasive phenotype. Cancer Research 67, 11742-11750 (2007).
Full journal article: www.bumc.bu.edu/whirc/files/2008/11/belguise_dmba_canres.pdf
5. Lee IP et al. Chemopreventive effects of green tea against cigarette smoke-induced mutations in humans. J Cell Biochem 1997; Suppl 27:68-75.
6. Jochmann N, et al. Green tea and cardiovascular disease: from molecular targets towards human health. Curr Opin Clin Nutr Metab Care. 2008 Nov;11(6):758-65.
7. Emad Al-Dujaili, et al. Effects of green tea consumption on blood pressure, total cholesterol, body weight and fat in healthy volunteers. 2009 Endocrine Abstracts 20: P470.
8. Osada K, Takahashi M, Hoshina S, Nakamura M, Nakamura S, Sugano M: Tea catechins inhibit cholesterol oxidation accompanying oxidation of low density lipoprotein in vitro. Comp Biochem Physiol Part C Toxicol Pharmacol 2001, 128:153-164.
9. Tsuneki H, et al. Effect of green tea on blood glucose levels and serum proteomic patterns in diabetic (db/db) mice and on glucose metabolism in healthy humans. BMC Pharmacol. 2004 Aug 26;4:18.
10. Boschmann M, Thielecke F. The effects of epigallocatechin-3-gallate on thermogenesis and fat oxidation in obese men: a pilot study. J Am Coll Nutr. 2007 Aug;26(4):389S-395S.
11. Kim HR, et al. Green tea protects rats against autoimmune arthritis by modulating disease-related immune events. The Journal of Nutrition. Nov. 2008:138(11):2111–2116.
12. Kuriyama S, et al. Green tea consumption and cognitive function: a cross-sectional study from the Tsurugaya Project 1. Am J Clin Nutr. 2006 Feb;83(2):355-61.
* Karen Lee Richards is Lead Expert specializing in Fibromyalgia and ME/CFS for HealthCentral's ChronicPainConnection (www.chronicpainconnection.com). Karen is co-founder of the National Fibromyalgia Association (NFA) and was Executive Editor of Fibromyalgia AWARE magazine for four years.
Note: This information has not been evaluated by the FDA. It is general and is not intended to prevent, diagnose, treat or cure any illness, condition, or disease. It is very important that you make no change in your healthcare plan or health support regimen without researching and discussing it in collaboration with your professional healthcare team.