| Green Tea Side Effects and Benefits |
Green Tea, Camellia sinensis, Epigallocatechin Gallate (EGCG)
Green tea is different from black tea, that green tea is not fermented. The active ingredients remain
unaltered in the tea. Traditionally, green tea was used for digestion, depression, immune
enhancement, detoxification, and to prolong life. Green tea has been used in conditions like:
atherosclerosis, high cholesterol, weight loss, high triglycerides, hives immune function and
infection. Green tea is also believed to reduce the risks for certain cancers.
Green tea contains, minerals, vitamins, oils, caffeine and polyphenols (particularly the
epigallocatechin gallate (EGCG)). Probably, epigallocatechin gallate (EGCG) is green tea’s key
active ingredient. [1]
GREEN TEA BENEFITS, RESEARCH FINDS
HEALTHY CHOLESTEROL PROFILE
Most studies have shown that green tea can lower the total cholesterol levels and improve the
cholesterol profile [2-6] A study also demonstrated that green tea protected against damage to LDL
(“bad”) cholesterol caused by oxygen. [7-9]
In a recent study, mice were treated with high cholesterol food with or without catechins for 35
weeks. Elevated inflammatory factors, high plasma cholesterol levels, severe atherosclerosis, liver
and renal dysfunctions were found in the no catechin fed mice (i.e. the control mice), while much
milder conditions were observed in the catechin fed mice. [23]
CANCER
Green tea may benefit people at risk of cancer. A study of 19,749 men and 22,012 women led by
Dr. Toru Naganuma, at Tohoku University School, Japan suggests drinking 5 cups of green tea
daily may lower the risk of developing certain blood cancers. During 9 years of follow up, 157
blood, bone marrow, and lymph system cancers developed in the study group. However, Dr. Toru
Naganuma found that the overall risk for blood cancers was 42 percent lower among study
participants who drank 5 or more, versus 1 or fewer, cups of green tea daily. [A1]
In a study of over 219,000 men and women over the age of 40, researchers found that about four
in five of the participants drank green tea daily for a prolonged period of time. One third of those --
notably women -- who drank five or more cups a day revealed a decreased risk of developing
gastric cancer. [A3]
In the gastrointestinal tract, green tea was found to activate intracellular antioxidants, inhibit
procarcinogen formation, and suppress angiogenesis and cancer cell proliferation. [20] Studies on
the preventive effect of green tea in esophageal cancer have produced inconsistent results;
however.several epidemiological, invitro and animal studies have shown that green tea has a
protective effect against lung cancer, breast cancer and prostate cancer. This preventive potential
of green tea against cancer is related to its active flavonoids - catechins. Epigallocatechin 3-o-
gallate, the major catechin in green tea, mediates diverse physiological and pharmacological
actions in bringing about the regression of the tumors and also lowers the risk of nonmalignant
cardiovascular proliferative diseases. These catechins exert diverse physiological effects against
cancers via several mechanisms, [10-16, 18]
NEUROPROTECTION
Reactive oxygen species (superoxide, hydroxyl radical and nitric oxide) generation and
inflammation play important roles in the age-associated cognitive decline and neuronal loss in
neurodegenerative diseases such as Alzheimer's, Parkinson's and Huntington's diseases. And,
accumulation of iron at sites where the neurons die is one of the characteristics of these diseases.
Thus, researchers think that the accumulation of iron and reactive oxygen species may lead to
neuronal toxicity and the related diseases. Tea flavonoids (catechins) have been reported to
possess potent iron-chelating, radical-scavenging and anti-inflammatory activities. Theoretically, it
may help protect neuronal death and against the neurodegenerative diseases. [17]
An ingredient in green tea, called epigallocatechin-3-gallate (EGCG) may help prevent Alzheimer's
disease. In a study of mice, EGCG decreased the production beta-amyloid. [24]
WEIGHT LOSS
Green tea may help weight loss. A recent study in Netherlands has shown that green tea reduced
body weight, waist, respiratory quotient and body fat. The researchers explained that High caffeine
intake was associated with weight loss through thermogenesis and fat oxidation and with
suppressed leptin in women. In habitual low caffeine consumers, the green tea-caffeine mixture
improved weight maintenance, partly through thermogenesis and fat oxidation. [22] However, more
studies are needed to confirm this claim..
STRESS
Green tea may benefit people at stress. A group also from Japan analyzed information on daily
green tea consumption, psychological distress as assessed by the Kessler 6-item psychological
distress scale, and other lifestyle factors. They found psychological distress affected 2,774 (6.6
percent) of the respondents in the questionnaire. Respondents who consumed more than five cups
of green tea daily were less likely to experience psychological distress than those who drank less
than one cup daily. [A2]
GREEN TEA SIDE EFFECTS
Overdose of green tea may lead to side effects. Because green tea contains caffeine, excessive
consumption of green tea may lead to the side sides such as insomnia and anxiety.
Green tea is iron-chelating , thus, green tea extract may inhibit the absorption of non-heme iron as
much as 26%. [21] To avoid the side effects of green tea, never overdose ourselves with green
tea. Discuss with your doctor for the green tea side effects.
References
1. Graham HN. Green tea composition, consumption, and polyphenol chemistry. Prev Med 1992;21:334–50. 2. Kono S et al.
Green tea consumption and serum lipid profiles: A cross-sectional study in Northern Kyushu, Japan. Prev Med 1992;21:526–31. 3.
Yamaguchi Y et al. Preventive effects of green tea extract on lipid abnormalities in serum, liver and aorta of mice fed an
atherogenic diet. Nip Yak Zas 1991;97:329–37. 4. Sagesaka-Mitane Y et al. Platelet aggregation inhibitors in hot water extract of
green tea. Chem Pharm Bull 1990;38:790–3. 5. Stensvold I et al. Tea consumption. Relationship to cholesterol, blood pressure,
and coronary and total mortality. Prev Med 1992;21:546–53. 6. Tsubono Y et al Green tea intake in relation to serum lipid levels in
middle-aged Japanese men and women. Ann Epidemiol 1997;7:280–4. 7. Serafini M et al. In vivo antioxidant effect of green tea
in man. Eur J Clin Nutr 1996;50:28–32. 8. Benzie IF et al. Consumption of green tea causes rapid increase in plasma antioxidant
power in humans. Nutr Cancer 1999;34:83–7. 9. Sasazuki S et al. Relation between green tea consumption and severity of
coronary atherosclerosis among Japanese men and women. Ann Epidemiol 2000;10:401–8. 10. Suganuma M et al. Green tea and
cancer chemoprevention. Mutat Res 1999;428:339–44. 11. Weisberger JH et al. Tea, or tea and milk, inhibit mammary gland and
colon carcinogenesis in rats. Cancer Lett 1997;114:323–7. 12. Yang CS et al. Polyphenols as inhibitors of carcinogenesis. Environ
Health Perspect 1997;105(Suppl 4):971–6 [review]. 13. Menon LG et al. Anti-metastatic activity of curcumin and catechin. Cancer
Lett 1999;141:159–65. 14. Mukhtar H et al. Green tea in chemoprevention of cancer. Toxicol Sci 1999;52(2 Suppl):111–7. 15.
Katiyar SK et al. Tea consumption and cancer. World Rev Nutr Diet 1996;79:154–84 [review]. 16. Kohlmeier L et al. Tea and
cancer prevention: an evaluation of the epidemiologic literature. Nutr Cancer 1997;27:1–13 [review]. 17. Mandel SA et al
Multifunctional activities of green tea catechins in neuroprotection. Modulation of cell survival genes, iron-dependent oxidative
stress and PKC signaling pathway. Neurosignals. 2005;14(1-2):46-60. 18. Doss MX et al, Trapping of growth factors by catechins: a
possible therapeutical target for prevention of proliferative diseases. J Nutr Biochem. 2005 May;16(5):259-66. 19. Crespy V et al A
review of the health effects of green tea catechins in in vivo animal models. J Nutr. 2004 Dec;134(12 Suppl):3431S-3440S. 20. Koo
MW et al Pharmacological effects of green tea on the gastrointestinal system. Eur J Pharmacol. 2004 Oct 1;500(1-3):177-85. 21.
Samman S et al. Green tea or rosemary extract added to foods reduces nonheme-iron absorption. Am J Clin Nutr 2001;73:607–12.
22. Westerterp-Plantenga MS et al Body weight loss and weight maintenance in relation to habitual caffeine intake and green tea
supplementation. Obes Res. 2005 Jul;13(7):1195-204. 23. Suzuki J et al, Dietary consumption of green tea catechins attenuate
hyperlipidaemia-induced atherosclerosis and systemic organ damage in mice. Acta Cardiol. 2005 Jun;60(3):271-6. 24. Green Tea
Compound Stops Alzheimer's in Mice HealthDay Online Publication, September 21, 2005 [A1] Green tea may curb risk of some
cancers, Reuters, October 13, 2009 [A2] Green tea reduces stress, Naturalprodcutsmarketplace.com, October 13, 2009 [A3] Drinking
lots of green tea could ward off stomach cancer in women, Relaxnews, Independent.co.uk, October 5, 2009
Green tea is different from black tea, that green tea is not fermented. The active ingredients remain
unaltered in the tea. Traditionally, green tea was used for digestion, depression, immune
enhancement, detoxification, and to prolong life. Green tea has been used in conditions like:
atherosclerosis, high cholesterol, weight loss, high triglycerides, hives immune function and
infection. Green tea is also believed to reduce the risks for certain cancers.
Green tea contains, minerals, vitamins, oils, caffeine and polyphenols (particularly the
epigallocatechin gallate (EGCG)). Probably, epigallocatechin gallate (EGCG) is green tea’s key
active ingredient. [1]
GREEN TEA BENEFITS, RESEARCH FINDS
HEALTHY CHOLESTEROL PROFILE
Most studies have shown that green tea can lower the total cholesterol levels and improve the
cholesterol profile [2-6] A study also demonstrated that green tea protected against damage to LDL
(“bad”) cholesterol caused by oxygen. [7-9]
In a recent study, mice were treated with high cholesterol food with or without catechins for 35
weeks. Elevated inflammatory factors, high plasma cholesterol levels, severe atherosclerosis, liver
and renal dysfunctions were found in the no catechin fed mice (i.e. the control mice), while much
milder conditions were observed in the catechin fed mice. [23]
CANCER
Green tea may benefit people at risk of cancer. A study of 19,749 men and 22,012 women led by
Dr. Toru Naganuma, at Tohoku University School, Japan suggests drinking 5 cups of green tea
daily may lower the risk of developing certain blood cancers. During 9 years of follow up, 157
blood, bone marrow, and lymph system cancers developed in the study group. However, Dr. Toru
Naganuma found that the overall risk for blood cancers was 42 percent lower among study
participants who drank 5 or more, versus 1 or fewer, cups of green tea daily. [A1]
In a study of over 219,000 men and women over the age of 40, researchers found that about four
in five of the participants drank green tea daily for a prolonged period of time. One third of those --
notably women -- who drank five or more cups a day revealed a decreased risk of developing
gastric cancer. [A3]
In the gastrointestinal tract, green tea was found to activate intracellular antioxidants, inhibit
procarcinogen formation, and suppress angiogenesis and cancer cell proliferation. [20] Studies on
the preventive effect of green tea in esophageal cancer have produced inconsistent results;
however.several epidemiological, invitro and animal studies have shown that green tea has a
protective effect against lung cancer, breast cancer and prostate cancer. This preventive potential
of green tea against cancer is related to its active flavonoids - catechins. Epigallocatechin 3-o-
gallate, the major catechin in green tea, mediates diverse physiological and pharmacological
actions in bringing about the regression of the tumors and also lowers the risk of nonmalignant
cardiovascular proliferative diseases. These catechins exert diverse physiological effects against
cancers via several mechanisms, [10-16, 18]
NEUROPROTECTION
Reactive oxygen species (superoxide, hydroxyl radical and nitric oxide) generation and
inflammation play important roles in the age-associated cognitive decline and neuronal loss in
neurodegenerative diseases such as Alzheimer's, Parkinson's and Huntington's diseases. And,
accumulation of iron at sites where the neurons die is one of the characteristics of these diseases.
Thus, researchers think that the accumulation of iron and reactive oxygen species may lead to
neuronal toxicity and the related diseases. Tea flavonoids (catechins) have been reported to
possess potent iron-chelating, radical-scavenging and anti-inflammatory activities. Theoretically, it
may help protect neuronal death and against the neurodegenerative diseases. [17]
An ingredient in green tea, called epigallocatechin-3-gallate (EGCG) may help prevent Alzheimer's
disease. In a study of mice, EGCG decreased the production beta-amyloid. [24]
WEIGHT LOSS
Green tea may help weight loss. A recent study in Netherlands has shown that green tea reduced
body weight, waist, respiratory quotient and body fat. The researchers explained that High caffeine
intake was associated with weight loss through thermogenesis and fat oxidation and with
suppressed leptin in women. In habitual low caffeine consumers, the green tea-caffeine mixture
improved weight maintenance, partly through thermogenesis and fat oxidation. [22] However, more
studies are needed to confirm this claim..
STRESS
Green tea may benefit people at stress. A group also from Japan analyzed information on daily
green tea consumption, psychological distress as assessed by the Kessler 6-item psychological
distress scale, and other lifestyle factors. They found psychological distress affected 2,774 (6.6
percent) of the respondents in the questionnaire. Respondents who consumed more than five cups
of green tea daily were less likely to experience psychological distress than those who drank less
than one cup daily. [A2]
GREEN TEA SIDE EFFECTS
Overdose of green tea may lead to side effects. Because green tea contains caffeine, excessive
consumption of green tea may lead to the side sides such as insomnia and anxiety.
Green tea is iron-chelating , thus, green tea extract may inhibit the absorption of non-heme iron as
much as 26%. [21] To avoid the side effects of green tea, never overdose ourselves with green
tea. Discuss with your doctor for the green tea side effects.
References
1. Graham HN. Green tea composition, consumption, and polyphenol chemistry. Prev Med 1992;21:334–50. 2. Kono S et al.
Green tea consumption and serum lipid profiles: A cross-sectional study in Northern Kyushu, Japan. Prev Med 1992;21:526–31. 3.
Yamaguchi Y et al. Preventive effects of green tea extract on lipid abnormalities in serum, liver and aorta of mice fed an
atherogenic diet. Nip Yak Zas 1991;97:329–37. 4. Sagesaka-Mitane Y et al. Platelet aggregation inhibitors in hot water extract of
green tea. Chem Pharm Bull 1990;38:790–3. 5. Stensvold I et al. Tea consumption. Relationship to cholesterol, blood pressure,
and coronary and total mortality. Prev Med 1992;21:546–53. 6. Tsubono Y et al Green tea intake in relation to serum lipid levels in
middle-aged Japanese men and women. Ann Epidemiol 1997;7:280–4. 7. Serafini M et al. In vivo antioxidant effect of green tea
in man. Eur J Clin Nutr 1996;50:28–32. 8. Benzie IF et al. Consumption of green tea causes rapid increase in plasma antioxidant
power in humans. Nutr Cancer 1999;34:83–7. 9. Sasazuki S et al. Relation between green tea consumption and severity of
coronary atherosclerosis among Japanese men and women. Ann Epidemiol 2000;10:401–8. 10. Suganuma M et al. Green tea and
cancer chemoprevention. Mutat Res 1999;428:339–44. 11. Weisberger JH et al. Tea, or tea and milk, inhibit mammary gland and
colon carcinogenesis in rats. Cancer Lett 1997;114:323–7. 12. Yang CS et al. Polyphenols as inhibitors of carcinogenesis. Environ
Health Perspect 1997;105(Suppl 4):971–6 [review]. 13. Menon LG et al. Anti-metastatic activity of curcumin and catechin. Cancer
Lett 1999;141:159–65. 14. Mukhtar H et al. Green tea in chemoprevention of cancer. Toxicol Sci 1999;52(2 Suppl):111–7. 15.
Katiyar SK et al. Tea consumption and cancer. World Rev Nutr Diet 1996;79:154–84 [review]. 16. Kohlmeier L et al. Tea and
cancer prevention: an evaluation of the epidemiologic literature. Nutr Cancer 1997;27:1–13 [review]. 17. Mandel SA et al
Multifunctional activities of green tea catechins in neuroprotection. Modulation of cell survival genes, iron-dependent oxidative
stress and PKC signaling pathway. Neurosignals. 2005;14(1-2):46-60. 18. Doss MX et al, Trapping of growth factors by catechins: a
possible therapeutical target for prevention of proliferative diseases. J Nutr Biochem. 2005 May;16(5):259-66. 19. Crespy V et al A
review of the health effects of green tea catechins in in vivo animal models. J Nutr. 2004 Dec;134(12 Suppl):3431S-3440S. 20. Koo
MW et al Pharmacological effects of green tea on the gastrointestinal system. Eur J Pharmacol. 2004 Oct 1;500(1-3):177-85. 21.
Samman S et al. Green tea or rosemary extract added to foods reduces nonheme-iron absorption. Am J Clin Nutr 2001;73:607–12.
22. Westerterp-Plantenga MS et al Body weight loss and weight maintenance in relation to habitual caffeine intake and green tea
supplementation. Obes Res. 2005 Jul;13(7):1195-204. 23. Suzuki J et al, Dietary consumption of green tea catechins attenuate
hyperlipidaemia-induced atherosclerosis and systemic organ damage in mice. Acta Cardiol. 2005 Jun;60(3):271-6. 24. Green Tea
Compound Stops Alzheimer's in Mice HealthDay Online Publication, September 21, 2005 [A1] Green tea may curb risk of some
cancers, Reuters, October 13, 2009 [A2] Green tea reduces stress, Naturalprodcutsmarketplace.com, October 13, 2009 [A3] Drinking
lots of green tea could ward off stomach cancer in women, Relaxnews, Independent.co.uk, October 5, 2009
| Studies suggest green tea may have benefit people at various aspects, as hthe green tea catechins are anti-oxidative, anti-inflammatory, anti-carcinogenic, anti-arteriosclerotic and anti-bacterial. [20] |
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