NYU Medical center Double-blind Studies Green Tea's effects on sun damage

NYU Medical center Double-blind Studies  

Green Tea's effects on  sun damage

Green tea contains high levels of substances called catechin polyphenols, known to possess strong antioxidant, anticarcinogenic, antitumorigenic, and even antibiotic properties. ^1,2 Based on these findings, as well as observational studies, ^3-8 green tea has become popular as a daily drink for preventing cancer and heart disease . However, some observational trials failed to find indications of benefit with green tea. ^9,10,11 Furthermore, only double-blind, placebo-controlled studies can prove a treatment effective, and there is little direct evidence of this type regarding green tea and cancer or heart disease prevention. ⁵² (For more information on why double-blind studies are so important, see Why Does this Database Rely on Double-blind Studies? )
Researchers have studied the potential benefits of green tea in people with high cholesterol . The overall evidence has been positive. One study found that green tea produced short-term improvements in cholesterol profile, but the benefits disappeared after 4 weeks. ²⁶ Another study evaluated a form of green tea enriched with the substance theaflavin. ²¹ In this large, 3-month trial, use of the tea product resulted in significant, ongoing reductions in LDL ("bad") cholesterol as compared to placebo. In a somewhat flawed double-blind study, a green tea extract enhanced with catechins also showed promise for reducing LDL levels. ⁴² Lastly, a 2011 review of 20 randomized trials involving 1,415 people found evidence that green tea catechins (145-3,000 mg/day for 3-24 weeks) reduced total and LDL cholesterol. ⁵⁶
Preliminary studies suggest that certain green tea polyphenols may help prevent skin cancer if they are applied directly to the skin. ¹² In addition, there is some evidence that green tea constituents might help protect the skin from sun damage . ^13,14,15 Unlike normal sunscreen preparations, green tea does not physically block ultraviolet light. Rather, it seems to protect cells from some of the damage caused by ultraviolet light. Because it works by such a different mechanism of action, green tea might offer synergistic benefits if combined with standard sunscreens. However, in an 8-week double-blind, placebo-controlled study of 40 women who already had symptoms of aging skin, combined use of oral green tea and a topical green tea cream failed to prove more effective than placebo. ²⁷ Some possible benefits were seen in microscopic evaluation of skin condition.
Topical green tea extracts have also shown a bit of promise for the treatment of cervical dysplasia , ²² while oral green tea extracts might reduce risk of prostate cancer, according to a small pilot study. ²⁸ Combining the results of 13 observational studies, researchers found conflicting evidence for green tea's effect on the risk of stomach cancer. ⁵³ In a Japanese pilot study, green tea extract supplements lowered the risk of recurrent colorectal polyps. ⁵⁴ In a review of nine observational studies involving over 5,600 cases of breast cancer, researchers failed to find reliable evidence for a reduction in the incidence of breast cancer. However, they did find weak evidence for a decrease in breast cancer recurrence among women who consumed more than 3 cups of green tea daily. . ⁵⁵
For more information on green tea's capacity to fight cancer see the Cancer Prevention article.
On a completely different note, one interesting study tested the effectiveness of gargling with green tea catechins as a means of preventing influenza . ³⁹ In this double-blind, placebo-controlled study, 124 residents of a Japanese nursing home gargled with green tea catechins or placebo for three months. All participants received standard influenza vaccine. The results showed that residents who gargled with the tea extract were less likely to develop influenza than those using the placebo. In addition, another double-blind study found preliminary evidence that oral consumption of a green tea extract might help prevent colds and flus . ⁴⁴
A small double-blind, placebo-controlled trial found weak evidence that green tea chew candy might reduce gum inflammation in individuals with periodontal disease (gingivitis). ¹⁶
Oral use of green tea extracts has shown a bit of promise for treating borderline diabetes. ⁴¹ However, one double-blind study failed to find that a combined extract of black and green tea was helpful for controlling blood sugar levels in people with type 2 diabetes . ⁴³ And a subsequent study failed to find any benefit for green tea extract in controlling blood sugar levels in obese people with diabetes. ⁵⁷
Green tea has been proposed as means of preventing liver disease , but the evidence for this use remains unconvincing. ^17,48
Green tea is sometimes recommended for weight loss on the basis of rather theoretical evidence that it speeds up metabolism. ²³ However, there is little direct scientific backing for this use. If green tea increases metabolism at all, the effect is extremely small. ^29-30 One study conducted in Thailand reported weight-loss benefits with green tea, ⁴⁵ as did a second study of oolong tea enriched with green tea extracts. ²⁴ However, a Dutch study failed to find green tea helpful for preventing weight regain after weight loss. ⁴⁶ In another study, use of green tea failed to produce significant weight loss in overweight women with polycystic ovary syndrome . ³¹ Green tea extract enriched with catechins has done somewhat better, enhancing weight loss in one substantial, but flawed trial. ⁴² However, a study in overweight Japanese children did not support the effectiveness of green tea catechins for weight reduction. ⁴⁷ Similar results were obtained in another placebo-controlled trial involving 78 overweight women after 12 weeks of treatment. ⁴⁹
One preliminary study, available only in abstract form, found some evidence that green tea cream may be helpful for rosacea . ²⁵ The results of another study weakly hint that green tea extracts taken orally might reduce symptoms of benign prostatic hyperplasia . ³²
One study found that inhaled tea catechins could reduce levels of resistant staph carried in the sputum of disabled seniors. ³³Note : Do not attempt to inhale green tea products.
*

Dosage  

Studies weakly suggest that 3 cups of green tea daily might provide protection against cancer.

References

* Snow JM. Camellia sinensi (L.) Kuntze (Theaceae). J Botanical Medicine. 1995;Autumn:28-32.

* Cao Y, Cao R. Angiogenesis inhibited by drinking tea [letter]. Nature. 1999;398:381.

* Stoner GD, Mukhtar H. Polyphenols as cancer chemopreventive agents. J Cell Biochem Suppl. 1995;22:169-180.

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

* Imai K, Nakachi K. Cross sectional study of effects of drinking green tea on cardiovascular and liver diseases. BMJ. 1995;310:693-696.

* Kono S, Shinchi K, Ikeda N, et al. Green tea consumption and serum lipid profiles: a cross-sectional study in northern Kyushu, Japan. Prev Med. 1992;21:526-531.

* Tsubono Y, Tsugane S. Green tea intake in relation to serum lipid levels in middle-aged Japanese men and women. Ann Epidemiol. 1997;7:280-284.

* van het Hof KH, de Boer HS, Wiseman SA, et al. Consumption of green or black tea does not increase resistance of low-density lipoprotein to oxidation in humans. Am J Clin Nutr. 1997;66:1125-1132.

* Kohlmeier L, Weterings KGC, Steck S, et al. Tea and cancer prevention: an evaluation of the epidemiologic literature. Nutr Cancer. 1997;27:1-13.

* Tsubono Y, Nishino Y, Komatsu S, et al. Green tea and the risk of gastric cancer in Japan. N Engl J Med. 2001;344:632-666.

* Galanis DJ, Kolonel LN, Lee J, et al. Intakes of selected foods and beverages and the incidence of gastric cancer among the Japanese residents of Hawaii: a prospective study. Int J Epidemiol. 1998;27:173-180.

* Katiyar SK, Ahmad N, Mukhtar H. Green tea and skin. Arch Dermatol. 2000;136:989-994.

* Katiyar SK, Matsui MS, Elmets CA, et al.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, Elmets CA, Agarwal R, et al. Protection against ultraviolet-B radiation-induced local and systemic suppression of contact hypersensitivity and edema responses in C3H/HeN mice by green tea polyphenols. Photochem Photobiol. 1995;62:855-861.

* Elmets CA, Singh D, Tubesing K, et al. Cutaneous photoprotection from ultraviolet injury by green tea polyphenols. J Am Acad Dermatol. 2001;44:425-432.

* Krahwinkel T, Willershausen B. The effect of sugar-free green tea chew candies on the degree of inflammation of the gingiva. Eur J Med Res. 2000;5:463-467.

* Imai K, Nakachi K. Cross sectional study of effects of drinking green tea on cardiovascular and liver diseases. BMJ. 1995;310:693-696.

* Hegarty VM, May HM, Khaw KT. Tea drinking and bone mineral density in older women. Am J Clin Nutr. 2000;71:1003-1007.

* Geleijnse JM, Launer LJ, Hofman A, et al. Tea flavonoids may protect against atherosclerosis: the Rotterdam Study. Arch Intern Med. 1999;159:2170-2174.

* Taylor JR, Wilt VM. Probable antagonism of warfarin by green tea. Ann Pharmacother. 1999;33:426-428.

* Maron DJ, Lu GP, Cai NS, et al. Cholesterol-lowering effect of a theaflavin-enriched green tea extract: a randomized controlled trial. Arch Intern Med . 2003;163:1448-53.

* Ahn WS, Yoo J, Huh SW, et al. Protective effects of green tea extracts (polyphenon E and EGCG) on human cervical lesions. Eur J Cancer Prev. 2003;12:383-90.

* 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.

* Nagao T, Komine Y, Soga S, et al. Ingestion of a tea rich in catechins leads to a reduction in body fat and malondialdehyde-modified LDL in men. Am J Clin Nutr. 2005;81:122-129.

*Syed A. AAD 63rd Annual Meeting: Poster 19. Presented: February 20, 2005.

* Diepvens K, Kovacs EM, Vogels N, et al. Metabolic effects of green tea and of phases of weight loss. Physiol Behav. 2005 Nov 4. [Epub ahead of print]

* Chiu AE, Chan JL, Kern DG, et al. Double-blinded, placebo-controlled trial of green tea extracts in the clinical and histologic appearance of photoaging skin. Dermatol Surg. 2005;31:855-860; discussion 860.

* Bettuzzi S, Brausi M, Rizzi F, et al. Chemoprevention of human prostate cancer by oral administration of green tea catechins in volunteers with high-grade prostate intraepithelial neoplasia: a preliminary report from a one-year proof-of-principle study. Cancer Res. 2006;66:1234-1240.

* Diepvens K, Kovacs EM, Nijs IM, et al. Effect of green tea on resting energy expenditure and substrate oxidation during weight loss in overweight females. Br J Nutr. 2005;94:1026-1034.

* Diepvens K, Kovacs EM, Vogels N, et al. Metabolic effects of green tea and of phases of weight loss. Physiol Behav. 2005 Nov 4. [Epub ahead of print]

* Chan CC, Koo MW, Ng EH, et al. Effects of Chinese green tea on weight, and hormonal and biochemical profiles in obese patients with polycystic ovary syndrome—a randomized placebo-controlled trial. J Soc Gynecol Investig. 2005;13:63-68.

* Bettuzzi S, Brausi M, Rizzi F, et al. Chemoprevention of human prostate cancer by oral administration of green tea catechins in volunteers with high-grade prostate intraepithelial neoplasia: a preliminary report from a one-year proof-of-principle study. Cancer Res. 2006;66:1234-1240.

* Yamada H, Tateishi M, Harada K, et al. A randomized clinical study of tea catechin inhalation effects on methicillin-resistant staphylococcus aureus in disabled elderly patients. J Am Med Dir Assoc. 2006;7:79-83.

* Product review of supplements for cancer prevention (green tea, lycopene, and selenium). Consumer Lab website. Available at: http://www.consumerlabs.com/results/cancer_supplements_green_tea_lycopene_selenium.asp . Accessed May 5, 2006.

* Bonkovsky HL. Hepatotoxicity associated with supplements containing Chinese green tea (Camellia sinensis). Ann Intern Med. 2006;144:68-71. Erratum in: Ann Intern Med. 2006;144:380.

* Gloro R, Hourmand-Ollivier I, Mosquet B, et al. Fulminant hepatitis during self-medication with hydroalcoholic extract of green tea. Eur J Gastroenterol Hepatol. 2005;17:1135-1137.

* Green tea mechanism urges caution for pregnant women. Nutra Ingredients website. http://nutraingredients.com/news/ng.asp?id=58807&n=dt76&c=tbtcgrwexqoosjy . Accessed September 20, 2005.

* Taylor JR, Wilt VM. Probable antagonism of warfarin by green tea. Ann Pharmacother. 1999;33:426-428.

* Yamada H, Takuma N, Daimon T, et al. Gargling with tea catechin extracts for the prevention of influenza infection in elderly nursing home residents: a prospective clinical study. J Altern Complement Med. 2006;12:669-672.

* Green tea extract (Green Lite): suspected association with hepatotoxicity. Canadian Adverse Reaction Newsletter. 2007;17.

* Fukino Y, Ikeda A, Maruyama K, et al. Randomized controlled trial for an effect of green tea-extract powder supplementation on glucose abnormalities. Eur J Clin Nutr. 2007 Jun 6. [Epub ahead of print]

* Nagao T, Hase T, Tokimitsu I. A green tea extract high in catechins reduces body fat and cardiovascular risks in humans. Obesity (Silver Spring). 2007;15:1473-1483.

* Mackenzie T, Leary L, Brooks WB. The effect of an extract of green and black tea on glucose control in adults with type 2 diabetes mellitus: double-blind randomized study. Metabolism. 2007;56:1340-1344.

* Rowe CA, Nantz MP, Bukowski JF, et al. Specific formulation of Camellia sinensis prevents cold and flu symptoms and enhances T cell function: a randomized, double-blind, placebo-controlled study. J Am Coll Nutr. 2007;26:445-452.

* Auvichayapat P, Prapochanung M, Tunkamnerdthai O, et al. Effectiveness of green tea on weight reduction in obese Thais: A randomized, controlled trial. Physiol Behav. 2007 Oct 18. [Epub ahead of print]

* Kovacs EM, Lejeune MP, Nijs I, et al. Effects of green tea on weight maintenance after body-weight loss. Br J Nutr. 2004;91:431-437.

* Matsuyama T, Tanaka Y, Kamimaki I, et al. Catechin safely improved higher levels of fatness, blood pressure, and cholesterol in children. Obesity (Silver Spring). 2008 Mar 20.

* Jin X, Zheng RH, Li YM. Green tea consumption and liver disease: a systematic review. Liver Int. 2008 May 14.

* Hsu CH, Tsai TH, Kao YH, et al. Effect of green tea extract on obese women: A randomized, double-blind, placebo-controlled clinical trial. Clin Nutr. 2008 May 9.

* Sarma DN, Barrett ML, Chavez ML, et al. Safety of green tea extracts : a systematic review by the US Pharmacopeia. Drug Saf. 2008;31:469-484.

* Alemdaroglu NC, Dietz U, Wolffram S, et al. Influence of green and black tea on folic acid pharmacokinetics in healthy volunteers: potential risk of diminished folic acid bioavailability. Biopharm Drug Dispos. 2008 Jun 12.

* Liu J, Xing J, Fei Y. Green tea ( Camellia sinensis ) and cancer prevention: a systematic review of randomized trials and epidemiological studies. Chin Med. 2008;3:12.

* Myung SK, Bae WK, Oh SM, et al. Green tea consumption and risk of stomach cancer: a meta-analysis of epidemiologic studies. Int J Cancer. 2009;124:670-677.

* Shimizu M, Fukutomi Y, Ninomiya M, et al. Green tea extracts for the prevention of metachronous colorectal adenomas: a pilot study. Cancer Epidemiol Biomarkers Prev. 2008;17:3020-3025.

* Ogunleye AA, Xue F, Michels KB. Green tea consumption and breast cancer risk or recurrence: a meta-analysis. Breast Cancer Res Treat. 2010 Jan;119(2):477.

* Kim A, Chiu A, Barone MK, et al. Green tea catechins decrease total and low-density lipoprotein cholesterol: a systematic review and meta-analysis. J Am Diet Assoc. 2011;111(11):1720-1729.

* Hsu CH, Liao YL, Lin SC, Tsai TH, Huang CJ, Chou P. Does supplementation with green tea extract improve insulin resistance in obese type 2 diabetics? A randomized, double-blind, and placebo-controlled clinical trial. Altern Med Rev. 2011;16(2):157-163.

Last reviewed August 2013 by EBSCO CAM Review Board

NYU Medical center Green Tea's effects on high cholesterol

NYU Medical center Double-blind Studies  

Green Tea's effects on high cholesterol

Green tea contains high levels of substances called catechin polyphenols, known to possess strong antioxidant, anticarcinogenic, antitumorigenic, and even antibiotic properties. ^1,2 Based on these findings, as well as observational studies, ^3-8 green tea has become popular as a daily drink for preventing cancer and heart disease . However, some observational trials failed to find indications of benefit with green tea. ^9,10,11 Furthermore, only double-blind, placebo-controlled studies can prove a treatment effective, and there is little direct evidence of this type regarding green tea and cancer or heart disease prevention. ⁵² (For more information on why double-blind studies are so important, see Why Does this Database Rely on Double-blind Studies? )
Researchers have studied the potential benefits of green tea in people with high cholesterol . The overall evidence has been positive. One study found that green tea produced short-term improvements in cholesterol profile, but the benefits disappeared after 4 weeks. ²⁶ Another study evaluated a form of green tea enriched with the substance theaflavin. ²¹ In this large, 3-month trial, use of the tea product resulted in significant, ongoing reductions in LDL ("bad") cholesterol as compared to placebo. In a somewhat flawed double-blind study, a green tea extract enhanced with catechins also showed promise for reducing LDL levels. ⁴² Lastly, a 2011 review of 20 randomized trials involving 1,415 people found evidence that green tea catechins (145-3,000 mg/day for 3-24 weeks) reduced total and LDL cholesterol. ⁵⁶
Preliminary studies suggest that certain green tea polyphenols may help prevent skin cancer if they are applied directly to the skin. ¹² In addition, there is some evidence that green tea constituents might help protect the skin from sun damage . ^13,14,15 Unlike normal sunscreen preparations, green tea does not physically block ultraviolet light. Rather, it seems to protect cells from some of the damage caused by ultraviolet light. Because it works by such a different mechanism of action, green tea might offer synergistic benefits if combined with standard sunscreens. However, in an 8-week double-blind, placebo-controlled study of 40 women who already had symptoms of aging skin, combined use of oral green tea and a topical green tea cream failed to prove more effective than placebo. ²⁷ Some possible benefits were seen in microscopic evaluation of skin condition.
Topical green tea extracts have also shown a bit of promise for the treatment of cervical dysplasia , ²² while oral green tea extracts might reduce risk of prostate cancer, according to a small pilot study. ²⁸ Combining the results of 13 observational studies, researchers found conflicting evidence for green tea's effect on the risk of stomach cancer. ⁵³ In a Japanese pilot study, green tea extract supplements lowered the risk of recurrent colorectal polyps. ⁵⁴ In a review of nine observational studies involving over 5,600 cases of breast cancer, researchers failed to find reliable evidence for a reduction in the incidence of breast cancer. However, they did find weak evidence for a decrease in breast cancer recurrence among women who consumed more than 3 cups of green tea daily. . ⁵⁵
For more information on green tea's capacity to fight cancer see the Cancer Prevention article.
On a completely different note, one interesting study tested the effectiveness of gargling with green tea catechins as a means of preventing influenza . ³⁹ In this double-blind, placebo-controlled study, 124 residents of a Japanese nursing home gargled with green tea catechins or placebo for three months. All participants received standard influenza vaccine. The results showed that residents who gargled with the tea extract were less likely to develop influenza than those using the placebo. In addition, another double-blind study found preliminary evidence that oral consumption of a green tea extract might help prevent colds and flus . ⁴⁴
A small double-blind, placebo-controlled trial found weak evidence that green tea chew candy might reduce gum inflammation in individuals with periodontal disease (gingivitis). ¹⁶
Oral use of green tea extracts has shown a bit of promise for treating borderline diabetes. ⁴¹ However, one double-blind study failed to find that a combined extract of black and green tea was helpful for controlling blood sugar levels in people with type 2 diabetes . ⁴³ And a subsequent study failed to find any benefit for green tea extract in controlling blood sugar levels in obese people with diabetes. ⁵⁷
Green tea has been proposed as means of preventing liver disease , but the evidence for this use remains unconvincing. ^17,48
Green tea is sometimes recommended for weight loss on the basis of rather theoretical evidence that it speeds up metabolism. ²³ However, there is little direct scientific backing for this use. If green tea increases metabolism at all, the effect is extremely small. ^29-30 One study conducted in Thailand reported weight-loss benefits with green tea, ⁴⁵ as did a second study of oolong tea enriched with green tea extracts. ²⁴ However, a Dutch study failed to find green tea helpful for preventing weight regain after weight loss. ⁴⁶ In another study, use of green tea failed to produce significant weight loss in overweight women with polycystic ovary syndrome . ³¹ Green tea extract enriched with catechins has done somewhat better, enhancing weight loss in one substantial, but flawed trial. ⁴² However, a study in overweight Japanese children did not support the effectiveness of green tea catechins for weight reduction. ⁴⁷ Similar results were obtained in another placebo-controlled trial involving 78 overweight women after 12 weeks of treatment. ⁴⁹
One preliminary study, available only in abstract form, found some evidence that green tea cream may be helpful for rosacea . ²⁵ The results of another study weakly hint that green tea extracts taken orally might reduce symptoms of benign prostatic hyperplasia . ³²
One study found that inhaled tea catechins could reduce levels of resistant staph carried in the sputum of disabled seniors. ³³Note : Do not attempt to inhale green tea products.
*

Dosage  

Studies weakly suggest that 3 cups of green tea daily might provide protection against cancer.

References

* Snow JM. Camellia sinensi (L.) Kuntze (Theaceae). J Botanical Medicine. 1995;Autumn:28-32.

* Cao Y, Cao R. Angiogenesis inhibited by drinking tea [letter]. Nature. 1999;398:381.

* Stoner GD, Mukhtar H. Polyphenols as cancer chemopreventive agents. J Cell Biochem Suppl. 1995;22:169-180.

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

* Imai K, Nakachi K. Cross sectional study of effects of drinking green tea on cardiovascular and liver diseases. BMJ. 1995;310:693-696.

* Kono S, Shinchi K, Ikeda N, et al. Green tea consumption and serum lipid profiles: a cross-sectional study in northern Kyushu, Japan. Prev Med. 1992;21:526-531.

* Tsubono Y, Tsugane S. Green tea intake in relation to serum lipid levels in middle-aged Japanese men and women. Ann Epidemiol. 1997;7:280-284.

* van het Hof KH, de Boer HS, Wiseman SA, et al. Consumption of green or black tea does not increase resistance of low-density lipoprotein to oxidation in humans. Am J Clin Nutr. 1997;66:1125-1132.

* Kohlmeier L, Weterings KGC, Steck S, et al. Tea and cancer prevention: an evaluation of the epidemiologic literature. Nutr Cancer. 1997;27:1-13.

* Tsubono Y, Nishino Y, Komatsu S, et al. Green tea and the risk of gastric cancer in Japan. N Engl J Med. 2001;344:632-666.

* Galanis DJ, Kolonel LN, Lee J, et al. Intakes of selected foods and beverages and the incidence of gastric cancer among the Japanese residents of Hawaii: a prospective study. Int J Epidemiol. 1998;27:173-180.

* Katiyar SK, Ahmad N, Mukhtar H. Green tea and skin. Arch Dermatol. 2000;136:989-994.

* Katiyar SK, Matsui MS, Elmets CA, et al.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, Elmets CA, Agarwal R, et al. Protection against ultraviolet-B radiation-induced local and systemic suppression of contact hypersensitivity and edema responses in C3H/HeN mice by green tea polyphenols. Photochem Photobiol. 1995;62:855-861.

* Elmets CA, Singh D, Tubesing K, et al. Cutaneous photoprotection from ultraviolet injury by green tea polyphenols. J Am Acad Dermatol. 2001;44:425-432.

* Krahwinkel T, Willershausen B. The effect of sugar-free green tea chew candies on the degree of inflammation of the gingiva. Eur J Med Res. 2000;5:463-467.

* Imai K, Nakachi K. Cross sectional study of effects of drinking green tea on cardiovascular and liver diseases. BMJ. 1995;310:693-696.

* Hegarty VM, May HM, Khaw KT. Tea drinking and bone mineral density in older women. Am J Clin Nutr. 2000;71:1003-1007.

* Geleijnse JM, Launer LJ, Hofman A, et al. Tea flavonoids may protect against atherosclerosis: the Rotterdam Study. Arch Intern Med. 1999;159:2170-2174.

* Taylor JR, Wilt VM. Probable antagonism of warfarin by green tea. Ann Pharmacother. 1999;33:426-428.

* Maron DJ, Lu GP, Cai NS, et al. Cholesterol-lowering effect of a theaflavin-enriched green tea extract: a randomized controlled trial. Arch Intern Med . 2003;163:1448-53.

* Ahn WS, Yoo J, Huh SW, et al. Protective effects of green tea extracts (polyphenon E and EGCG) on human cervical lesions. Eur J Cancer Prev. 2003;12:383-90.

* 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.

* Nagao T, Komine Y, Soga S, et al. Ingestion of a tea rich in catechins leads to a reduction in body fat and malondialdehyde-modified LDL in men. Am J Clin Nutr. 2005;81:122-129.

*Syed A. AAD 63rd Annual Meeting: Poster 19. Presented: February 20, 2005.

* Diepvens K, Kovacs EM, Vogels N, et al. Metabolic effects of green tea and of phases of weight loss. Physiol Behav. 2005 Nov 4. [Epub ahead of print]

* Chiu AE, Chan JL, Kern DG, et al. Double-blinded, placebo-controlled trial of green tea extracts in the clinical and histologic appearance of photoaging skin. Dermatol Surg. 2005;31:855-860; discussion 860.

* Bettuzzi S, Brausi M, Rizzi F, et al. Chemoprevention of human prostate cancer by oral administration of green tea catechins in volunteers with high-grade prostate intraepithelial neoplasia: a preliminary report from a one-year proof-of-principle study. Cancer Res. 2006;66:1234-1240.

* Diepvens K, Kovacs EM, Nijs IM, et al. Effect of green tea on resting energy expenditure and substrate oxidation during weight loss in overweight females. Br J Nutr. 2005;94:1026-1034.

* Diepvens K, Kovacs EM, Vogels N, et al. Metabolic effects of green tea and of phases of weight loss. Physiol Behav. 2005 Nov 4. [Epub ahead of print]

* Chan CC, Koo MW, Ng EH, et al. Effects of Chinese green tea on weight, and hormonal and biochemical profiles in obese patients with polycystic ovary syndrome—a randomized placebo-controlled trial. J Soc Gynecol Investig. 2005;13:63-68.

* Bettuzzi S, Brausi M, Rizzi F, et al. Chemoprevention of human prostate cancer by oral administration of green tea catechins in volunteers with high-grade prostate intraepithelial neoplasia: a preliminary report from a one-year proof-of-principle study. Cancer Res. 2006;66:1234-1240.

* Yamada H, Tateishi M, Harada K, et al. A randomized clinical study of tea catechin inhalation effects on methicillin-resistant staphylococcus aureus in disabled elderly patients. J Am Med Dir Assoc. 2006;7:79-83.

* Product review of supplements for cancer prevention (green tea, lycopene, and selenium). Consumer Lab website. Available at: http://www.consumerlabs.com/results/cancer_supplements_green_tea_lycopene_selenium.asp . Accessed May 5, 2006.

* Bonkovsky HL. Hepatotoxicity associated with supplements containing Chinese green tea (Camellia sinensis). Ann Intern Med. 2006;144:68-71. Erratum in: Ann Intern Med. 2006;144:380.

* Gloro R, Hourmand-Ollivier I, Mosquet B, et al. Fulminant hepatitis during self-medication with hydroalcoholic extract of green tea. Eur J Gastroenterol Hepatol. 2005;17:1135-1137.

* Green tea mechanism urges caution for pregnant women. Nutra Ingredients website. http://nutraingredients.com/news/ng.asp?id=58807&n=dt76&c=tbtcgrwexqoosjy . Accessed September 20, 2005.

* Taylor JR, Wilt VM. Probable antagonism of warfarin by green tea. Ann Pharmacother. 1999;33:426-428.

* Yamada H, Takuma N, Daimon T, et al. Gargling with tea catechin extracts for the prevention of influenza infection in elderly nursing home residents: a prospective clinical study. J Altern Complement Med. 2006;12:669-672.

* Green tea extract (Green Lite): suspected association with hepatotoxicity. Canadian Adverse Reaction Newsletter. 2007;17.

* Fukino Y, Ikeda A, Maruyama K, et al. Randomized controlled trial for an effect of green tea-extract powder supplementation on glucose abnormalities. Eur J Clin Nutr. 2007 Jun 6. [Epub ahead of print]

* Nagao T, Hase T, Tokimitsu I. A green tea extract high in catechins reduces body fat and cardiovascular risks in humans. Obesity (Silver Spring). 2007;15:1473-1483.

* Mackenzie T, Leary L, Brooks WB. The effect of an extract of green and black tea on glucose control in adults with type 2 diabetes mellitus: double-blind randomized study. Metabolism. 2007;56:1340-1344.

* Rowe CA, Nantz MP, Bukowski JF, et al. Specific formulation of Camellia sinensis prevents cold and flu symptoms and enhances T cell function: a randomized, double-blind, placebo-controlled study. J Am Coll Nutr. 2007;26:445-452.

* Auvichayapat P, Prapochanung M, Tunkamnerdthai O, et al. Effectiveness of green tea on weight reduction in obese Thais: A randomized, controlled trial. Physiol Behav. 2007 Oct 18. [Epub ahead of print]

* Kovacs EM, Lejeune MP, Nijs I, et al. Effects of green tea on weight maintenance after body-weight loss. Br J Nutr. 2004;91:431-437.

* Matsuyama T, Tanaka Y, Kamimaki I, et al. Catechin safely improved higher levels of fatness, blood pressure, and cholesterol in children. Obesity (Silver Spring). 2008 Mar 20.

* Jin X, Zheng RH, Li YM. Green tea consumption and liver disease: a systematic review. Liver Int. 2008 May 14.

* Hsu CH, Tsai TH, Kao YH, et al. Effect of green tea extract on obese women: A randomized, double-blind, placebo-controlled clinical trial. Clin Nutr. 2008 May 9.

* Sarma DN, Barrett ML, Chavez ML, et al. Safety of green tea extracts : a systematic review by the US Pharmacopeia. Drug Saf. 2008;31:469-484.

* Alemdaroglu NC, Dietz U, Wolffram S, et al. Influence of green and black tea on folic acid pharmacokinetics in healthy volunteers: potential risk of diminished folic acid bioavailability. Biopharm Drug Dispos. 2008 Jun 12.

* Liu J, Xing J, Fei Y. Green tea ( Camellia sinensis ) and cancer prevention: a systematic review of randomized trials and epidemiological studies. Chin Med. 2008;3:12.

* Myung SK, Bae WK, Oh SM, et al. Green tea consumption and risk of stomach cancer: a meta-analysis of epidemiologic studies. Int J Cancer. 2009;124:670-677.

* Shimizu M, Fukutomi Y, Ninomiya M, et al. Green tea extracts for the prevention of metachronous colorectal adenomas: a pilot study. Cancer Epidemiol Biomarkers Prev. 2008;17:3020-3025.

* Ogunleye AA, Xue F, Michels KB. Green tea consumption and breast cancer risk or recurrence: a meta-analysis. Breast Cancer Res Treat. 2010 Jan;119(2):477.

* Kim A, Chiu A, Barone MK, et al. Green tea catechins decrease total and low-density lipoprotein cholesterol: a systematic review and meta-analysis. J Am Diet Assoc. 2011;111(11):1720-1729.

* Hsu CH, Liao YL, Lin SC, Tsai TH, Huang CJ, Chou P. Does supplementation with green tea extract improve insulin resistance in obese type 2 diabetics? A randomized, double-blind, and placebo-controlled clinical trial. Altern Med Rev. 2011;16(2):157-163.

Last reviewed August 2013 by EBSCO CAM Review Board

Source: University of Maryland Medical study of Green tea and Liver disease

Green tea

Source:  University of Maryland Medical study of Green tea and Liver disease

 

Casteas offers the best custom tea blends and the best organic tea blends because we blend just before shipping, the best teas for headaches also the best teas for weight loss if that is one of your goals, are fresh Casteas.  We would love to trade links with likeminded people dedicated to the same Ideals as Casteas we look forward to your friendships.

Tea has been cultivated for centuries, beginning in India and China. Today, tea is the most widely consumed beverage in the world, second only to water. Hundreds of millions of people drink tea, and studies suggest that green tea (Camellia sinesis) in particular has many health benefits.
There are three main varieties of tea -- green, black, and oolong. The difference is in how the teas are processed. Green tea is made from unfermented leaves and reportedly contains the highest concentration of powerful antioxidants called polyphenols. Antioxidants are substances that fight free radicals -- damaging compounds in the body that change cells, damage DNA, and even cause cell death. Many scientists believe that free radicals contribute to the aging process as well as the development of a number of health problems, including cancer and heart disease. Antioxidants such as polyphenols in green tea can neutralize free radicals and may reduce or even help prevent some of the damage they cause.
In traditional Chinese and Indian medicine, practitioners used green tea as a stimulant, a diuretic (to help rid the body of excess fluid), an astringent (to control bleeding and help heal wounds), and to improve heart health. Other traditional uses of green tea include treating gas, regulating body temperature and blood sugar, promoting digestion, and improving mental processes.
Green tea has been extensively studied in people, animals, and laboratory experiments. Results from these studies suggest that green tea may help treat the following health conditions:
Atherosclerosis
Clinical studies that look at populations of people indicate that the antioxidant properties of green tea may help prevent atherosclerosis, particularly coronary artery disease. Population-based studies are studies that follow large groups of people over time or studies that compare groups of people living in different cultures or with different diets.
Researchers aren't sure why green tea reduces the risk of heart disease by lowering cholesterol and triglyceride levels. Studies show that black tea has similar effects. In fact, researchers estimate that the rate of heart attack decreases by 11% with consumption of 3 cups of tea per day.
In May 2006, however, the U.S. Food and Drug Administration (FDA) rejected a petition from teamakers to allow tea labels to claim that green tea reduces the risk of heart disease. The FDA concluded that there is no credible evidence to support that claim.
High cholesterol
Research shows that green tea lowers total cholesterol and raises HDL ("good") cholesterol in both animals and people. One population-based clinical study found that men who drink green tea are more likely to have lower total cholesterol than those who do not drink green tea.
Results from one animal study suggest that polyphenols in green tea may block cholesterol from being absorbed in the intestine and also help the body get rid of cholesterol. In another small study of male smokers, researchers found that green tea significantly reduced blood levels of harmful LDL cholesterol.
Cancer
Several population-based clinical studies have shown that both green and black teas may help protect against cancer. For example, cancer rates tend to be low in countries such as Japan where people regularly consume green tea. However, it is not possible to know for sure from these population-based studies whether green tea actually prevents cancer in people.
Early clinical studies suggest that the polyphenols in tea, especially green tea, may play an important role in the prevention of cancer. Researchers also believe that polyphenols help kill cancerous cells and stop them from growing.
Bladder cancer. Only a few clinical studies have examined the relationship between bladder cancer and drinking tea. In one study that compared people with and without bladder cancer, researchers found that women who drank black tea and powdered green tea were less likely to develop bladder cancer. A follow-up clinical study by the same group of researchers revealed that people with bladder cancer -- particularly men -- who drank green tea had a better 5-year survival rate than those who did not.
Breast cancer. Clinical studies in animals and test tubes suggest that polyphenols in green tea inhibit the growth of breast cancer cells. In one study of 472 women with various stages of breast cancer, researchers found that women who drank the most green tea had the least spread of cancer. It was especially true in premenopausal women in the early stages of breast cancer. They also found that women with early stages of the disease who drank at least 5 cups of tea every day before being diagnosed with cancer were less likely to have the cancer come back after they finished treatment. However, women with late stages of breast cancer had little or no improvement from drinking green tea.
There is no clear evidence one way or the other about green tea and breast cancer prevention. In one very large study, researchers found that drinking tea, green or any other type, was not associated with a reduced risk of breast cancer. However, when the researchers broke down the sample by age, they found that women under the age of 50 who consumed 3 or more cups of tea per day were 37% less likely to develop breast cancer compared to women who didn't drink tea.
Ovarian cancer. In a clinical study done with ovarian cancer patients in China, researchers found that women who drank at least one cup of green tea per day lived longer with the disease than those who didn’t drink green tea. In fact, those who drank the most tea, lived the longest. But other studies found no beneficial effects.
Colorectal cancer. Clinical studies on the effects of green tea on colon or rectal cancer have showed conflicting results. Some studies show decreased risk in those who drink the tea, while others show increased risk. In one study, women who drank 5 or more cups of green tea per day had a lower risk of colorectal cancer compared to non-tea-drinkers. There was no protective effect for men, however. Other studies show that drinking tea regularly may reduce the risk of colorectal cancer in women. More research is needed before researchers can recommend green tea for the prevention of colorectal cancer.
Esophageal cancer. Studies in laboratory animals have found that green tea polyphenols inhibit the growth of esophageal cancer cells. However, studies in people have produced conflicting findings. For example, one large-scale population-based clinical study found that green tea offered protection against the development of esophageal cancer, particularly among women. Another population-based clinical study found just the opposite -- green tea consumption was associated with an increased risk of esophageal cancer. In fact, the stronger and hotter the tea, the greater the risk. Given these conflicting results, more research is needed before scientists can recommend green tea for the prevention of esophageal cancer.
Lung cancer. While green tea polyphenols have been shown to inhibit the growth of human lung cancer cells in test tubes, few clinical studies have looked at the link between drinking green tea and lung cancer in people. And even these studies have been conflicting. One population-based study found that Okinawan tea -- similar to green tea but partially fermented -- was associated with lower lung cancer risk, particularly among women. But a second clinical study found that green tea and black tea increased the risk of lung cancer. More studies are needed before researchers can draw any conclusions about green tea and lung cancer.
Pancreatic cancer. In one large-scale clinical study researchers compared green tea drinkers with non-drinkers and found that those who drank the most tea were less likely to develop pancreatic cancer. This was particularly true for women -- those who drank the most green tea were half as likely to develop pancreatic cancer as those who drank less tea. Men who drank the most tea were 37% less likely to develop pancreatic cancer.
However, it is not clear from this population-based study whether green tea is solely responsible for lowering pancreatic cancer risk. More studies in animals and people are needed before researchers can recommend green tea for the prevention of pancreatic cancer.
Prostate cancer. Laboratory studies have found that green tea extracts prevent the growth of prostate cancer cells in test tubes. In a large clinical study in Southeast China researchers found that the risk of prostate cancer went down with increasing frequency, duration and quantity of green tea consumption. However, both green and black tea extracts also stimulated genes that cause cells to be less sensitive to chemotherapy drugs. People who are undergoing chemotherapy should ask their doctors before drinking green or black tea, or taking tea supplements.
Skin cancer. The main polyphenol in green tea is epigallocatechin gallate (EGCG). Scientific studies suggest that EGCG and green tea polyphenols have anti-inflammatory and anticancer properties that may help prevent the development and growth of skin tumors.
Stomach cancer. Laboratory studies have found that green tea polyphenols inhibit the growth of stomach cancer cells in test tubes, but studies in people have been less conclusive. In two studies that compared green tea drinkers with non-drinkers, researchers found that people who drank tea were about half as likely to develop stomach cancer and stomach inflammation as those who did not drink green tea. However, a clinical study with more than 26,000 men and women in Japan found no association between green tea and stomach cancer risk. Some studies even suggest that green tea may increase the risk of stomach cancer.
More clinical studies are underway to see whether green tea helps reduce the risk of stomach cancer.
Inflammatory Bowel Disease (IBD)
Green tea may help reduce inflammation associated with Crohn's disease and ulcerative colitis, the two types of IBD. If green tea proves to help prevent colon cancer, it would also help those with IBD because they are at higher risk for colon cancer.
Diabetes
Green tea has been used traditionally to control blood sugar levels. Animal studies suggest that green tea may help prevent the development of type 1 diabetes and slow the progression once it has developed. In people with type 1 diabetes, their bodies make little or no insulin, which helps convert glucose or sugar into energy. Green tea may help regulate glucose in the body.
A few small clinical studies have found that taking a green tea extract daily lowered the hemoglobin A1c level in people with borderline diabetes.
Liver disease
Population-based clinical studies have shown that men who drink more than 10 cups of green tea per day are less likely to develop liver problems. Green tea also seems to protect the liver from the damaging effects of toxic substances such as alcohol. Animal studies have shown that green tea helps protect against liver tumors in mice.
Results from several animal and human studies suggest that one of the polyphenols in green tea, known as catechin, may help treat viral hepatitis, an inflammation of the liver. In these studies, catechin was used by itself in very high amounts. It is not clear whether green tea, which has a lower concentration of catechins, would have the same benefits.
10 cups of green tea a day could cause problems because of the high level of caffeine consumed. Ask your doctor about the best way to include green tea in your treatment.
Weight loss
Clinical studies suggest that green tea extract may boost metabolism and help burn fat. One study found that the combination of green tea and caffeine improved weight loss and maintenance in people who were overweight and moderately obese. Some researchers think that substances in green tea known as catechins are responsible for the herb's fat-burning effect.
Other uses
One small study found that drinking green tea helped prevent dental cavities. More studies need to be done. Green tea may also be useful in inflammatory diseases, such as arthritis. Research suggests that green tea may help arthritis by reducing inflammation and slowing the breakdown of cartilage. Chemicals in green tea may also be help treat genital warts and prevent symptoms of colds and flu. Studies also show that drinking green tea is associated with reduced risk of dying from any cause.

Plant Description

Green, black, and oolong tea are all derived from the leaves of the Camellia sinensis plant. Originally cultivated in East Asia, this plant grows as large as a shrub or tree. Today, Camellia sinensis grows throughout Asia and parts of the Middle East and Africa.
People in Asian countries more commonly consume green and oolong tea while black tea is most popular in the United States. Green tea is prepared from unfermented leaves, the leaves of oolong tea are partially fermented, and black tea is fully fermented. The more the leaves are fermented, the lower the polyphenol content (See: "What's It Made Of?") and the higher the caffeine content. Green tea has the highest polyphenol content while black tea has roughly 2 - 3 times the caffeine content of green tea.

What's It Made Of?

Researchers think the health-giving properties of green tea are mostly due to polyphenols, chemicals with potent antioxidant properties. In fact, the antioxidant effects of polyphenols seem to be greater than vitamin C. The polyphenols in green tea also give it a somewhat bitter flavor.
Polyphenols contained in teas are classified as catechins. Green tea contains six primary catechin compounds: catechin, gallaogatechin, epicatechin, epigallocatechin, epicatechin gallate, and apigallocatechin gallate (also known as EGCG). EGCG is the most studied polyphenol component in green tea and the most active.
Green tea also contains alkaloids including caffeine, theobromine, and theophylline. They provide green tea's stimulant effects. L-theanine, an amino acid compound found in green tea, has been studied for its calming effects on the nervous system.

Source: University of Maryland Medical study of Green tea and Inflammatory Bowel Disease (IBD)

Green tea

Source:  University of Maryland Medical study of Green tea and Inflammatory Bowel Disease (IBD)

 

Casteas offers the best custom tea blends and the best organic tea blends because we blend just before shipping, the best teas for headaches also the best teas for weight loss if that is one of your goals, are fresh Casteas.  We would love to trade links with likeminded people dedicated to the same Ideals as Casteas we look forward to your friendships.

Tea has been cultivated for centuries, beginning in India and China. Today, tea is the most widely consumed beverage in the world, second only to water. Hundreds of millions of people drink tea, and studies suggest that green tea (Camellia sinesis) in particular has many health benefits.
There are three main varieties of tea -- green, black, and oolong. The difference is in how the teas are processed. Green tea is made from unfermented leaves and reportedly contains the highest concentration of powerful antioxidants called polyphenols. Antioxidants are substances that fight free radicals -- damaging compounds in the body that change cells, damage DNA, and even cause cell death. Many scientists believe that free radicals contribute to the aging process as well as the development of a number of health problems, including cancer and heart disease. Antioxidants such as polyphenols in green tea can neutralize free radicals and may reduce or even help prevent some of the damage they cause.
In traditional Chinese and Indian medicine, practitioners used green tea as a stimulant, a diuretic (to help rid the body of excess fluid), an astringent (to control bleeding and help heal wounds), and to improve heart health. Other traditional uses of green tea include treating gas, regulating body temperature and blood sugar, promoting digestion, and improving mental processes.
Green tea has been extensively studied in people, animals, and laboratory experiments. Results from these studies suggest that green tea may help treat the following health conditions:
Atherosclerosis
Clinical studies that look at populations of people indicate that the antioxidant properties of green tea may help prevent atherosclerosis, particularly coronary artery disease. Population-based studies are studies that follow large groups of people over time or studies that compare groups of people living in different cultures or with different diets.
Researchers aren't sure why green tea reduces the risk of heart disease by lowering cholesterol and triglyceride levels. Studies show that black tea has similar effects. In fact, researchers estimate that the rate of heart attack decreases by 11% with consumption of 3 cups of tea per day.
In May 2006, however, the U.S. Food and Drug Administration (FDA) rejected a petition from teamakers to allow tea labels to claim that green tea reduces the risk of heart disease. The FDA concluded that there is no credible evidence to support that claim.
High cholesterol
Research shows that green tea lowers total cholesterol and raises HDL ("good") cholesterol in both animals and people. One population-based clinical study found that men who drink green tea are more likely to have lower total cholesterol than those who do not drink green tea.
Results from one animal study suggest that polyphenols in green tea may block cholesterol from being absorbed in the intestine and also help the body get rid of cholesterol. In another small study of male smokers, researchers found that green tea significantly reduced blood levels of harmful LDL cholesterol.
Cancer
Several population-based clinical studies have shown that both green and black teas may help protect against cancer. For example, cancer rates tend to be low in countries such as Japan where people regularly consume green tea. However, it is not possible to know for sure from these population-based studies whether green tea actually prevents cancer in people.
Early clinical studies suggest that the polyphenols in tea, especially green tea, may play an important role in the prevention of cancer. Researchers also believe that polyphenols help kill cancerous cells and stop them from growing.
Bladder cancer. Only a few clinical studies have examined the relationship between bladder cancer and drinking tea. In one study that compared people with and without bladder cancer, researchers found that women who drank black tea and powdered green tea were less likely to develop bladder cancer. A follow-up clinical study by the same group of researchers revealed that people with bladder cancer -- particularly men -- who drank green tea had a better 5-year survival rate than those who did not.
Breast cancer. Clinical studies in animals and test tubes suggest that polyphenols in green tea inhibit the growth of breast cancer cells. In one study of 472 women with various stages of breast cancer, researchers found that women who drank the most green tea had the least spread of cancer. It was especially true in premenopausal women in the early stages of breast cancer. They also found that women with early stages of the disease who drank at least 5 cups of tea every day before being diagnosed with cancer were less likely to have the cancer come back after they finished treatment. However, women with late stages of breast cancer had little or no improvement from drinking green tea.
There is no clear evidence one way or the other about green tea and breast cancer prevention. In one very large study, researchers found that drinking tea, green or any other type, was not associated with a reduced risk of breast cancer. However, when the researchers broke down the sample by age, they found that women under the age of 50 who consumed 3 or more cups of tea per day were 37% less likely to develop breast cancer compared to women who didn't drink tea.
Ovarian cancer. In a clinical study done with ovarian cancer patients in China, researchers found that women who drank at least one cup of green tea per day lived longer with the disease than those who didn’t drink green tea. In fact, those who drank the most tea, lived the longest. But other studies found no beneficial effects.
Colorectal cancer. Clinical studies on the effects of green tea on colon or rectal cancer have showed conflicting results. Some studies show decreased risk in those who drink the tea, while others show increased risk. In one study, women who drank 5 or more cups of green tea per day had a lower risk of colorectal cancer compared to non-tea-drinkers. There was no protective effect for men, however. Other studies show that drinking tea regularly may reduce the risk of colorectal cancer in women. More research is needed before researchers can recommend green tea for the prevention of colorectal cancer.
Esophageal cancer. Studies in laboratory animals have found that green tea polyphenols inhibit the growth of esophageal cancer cells. However, studies in people have produced conflicting findings. For example, one large-scale population-based clinical study found that green tea offered protection against the development of esophageal cancer, particularly among women. Another population-based clinical study found just the opposite -- green tea consumption was associated with an increased risk of esophageal cancer. In fact, the stronger and hotter the tea, the greater the risk. Given these conflicting results, more research is needed before scientists can recommend green tea for the prevention of esophageal cancer.
Lung cancer. While green tea polyphenols have been shown to inhibit the growth of human lung cancer cells in test tubes, few clinical studies have looked at the link between drinking green tea and lung cancer in people. And even these studies have been conflicting. One population-based study found that Okinawan tea -- similar to green tea but partially fermented -- was associated with lower lung cancer risk, particularly among women. But a second clinical study found that green tea and black tea increased the risk of lung cancer. More studies are needed before researchers can draw any conclusions about green tea and lung cancer.
Pancreatic cancer. In one large-scale clinical study researchers compared green tea drinkers with non-drinkers and found that those who drank the most tea were less likely to develop pancreatic cancer. This was particularly true for women -- those who drank the most green tea were half as likely to develop pancreatic cancer as those who drank less tea. Men who drank the most tea were 37% less likely to develop pancreatic cancer.
However, it is not clear from this population-based study whether green tea is solely responsible for lowering pancreatic cancer risk. More studies in animals and people are needed before researchers can recommend green tea for the prevention of pancreatic cancer.
Prostate cancer. Laboratory studies have found that green tea extracts prevent the growth of prostate cancer cells in test tubes. In a large clinical study in Southeast China researchers found that the risk of prostate cancer went down with increasing frequency, duration and quantity of green tea consumption. However, both green and black tea extracts also stimulated genes that cause cells to be less sensitive to chemotherapy drugs. People who are undergoing chemotherapy should ask their doctors before drinking green or black tea, or taking tea supplements.
Skin cancer. The main polyphenol in green tea is epigallocatechin gallate (EGCG). Scientific studies suggest that EGCG and green tea polyphenols have anti-inflammatory and anticancer properties that may help prevent the development and growth of skin tumors.
Stomach cancer. Laboratory studies have found that green tea polyphenols inhibit the growth of stomach cancer cells in test tubes, but studies in people have been less conclusive. In two studies that compared green tea drinkers with non-drinkers, researchers found that people who drank tea were about half as likely to develop stomach cancer and stomach inflammation as those who did not drink green tea. However, a clinical study with more than 26,000 men and women in Japan found no association between green tea and stomach cancer risk. Some studies even suggest that green tea may increase the risk of stomach cancer.
More clinical studies are underway to see whether green tea helps reduce the risk of stomach cancer.
Inflammatory Bowel Disease (IBD)
Green tea may help reduce inflammation associated with Crohn's disease and ulcerative colitis, the two types of IBD. If green tea proves to help prevent colon cancer, it would also help those with IBD because they are at higher risk for colon cancer.
Diabetes
Green tea has been used traditionally to control blood sugar levels. Animal studies suggest that green tea may help prevent the development of type 1 diabetes and slow the progression once it has developed. In people with type 1 diabetes, their bodies make little or no insulin, which helps convert glucose or sugar into energy. Green tea may help regulate glucose in the body.
A few small clinical studies have found that taking a green tea extract daily lowered the hemoglobin A1c level in people with borderline diabetes.
Liver disease
Population-based clinical studies have shown that men who drink more than 10 cups of green tea per day are less likely to develop liver problems. Green tea also seems to protect the liver from the damaging effects of toxic substances such as alcohol. Animal studies have shown that green tea helps protect against liver tumors in mice.
Results from several animal and human studies suggest that one of the polyphenols in green tea, known as catechin, may help treat viral hepatitis, an inflammation of the liver. In these studies, catechin was used by itself in very high amounts. It is not clear whether green tea, which has a lower concentration of catechins, would have the same benefits.
10 cups of green tea a day could cause problems because of the high level of caffeine consumed. Ask your doctor about the best way to include green tea in your treatment.
Weight loss
Clinical studies suggest that green tea extract may boost metabolism and help burn fat. One study found that the combination of green tea and caffeine improved weight loss and maintenance in people who were overweight and moderately obese. Some researchers think that substances in green tea known as catechins are responsible for the herb's fat-burning effect.
Other uses
One small study found that drinking green tea helped prevent dental cavities. More studies need to be done. Green tea may also be useful in inflammatory diseases, such as arthritis. Research suggests that green tea may help arthritis by reducing inflammation and slowing the breakdown of cartilage. Chemicals in green tea may also be help treat genital warts and prevent symptoms of colds and flu. Studies also show that drinking green tea is associated with reduced risk of dying from any cause.

Plant Description

Green, black, and oolong tea are all derived from the leaves of the Camellia sinensis plant. Originally cultivated in East Asia, this plant grows as large as a shrub or tree. Today, Camellia sinensis grows throughout Asia and parts of the Middle East and Africa.
People in Asian countries more commonly consume green and oolong tea while black tea is most popular in the United States. Green tea is prepared from unfermented leaves, the leaves of oolong tea are partially fermented, and black tea is fully fermented. The more the leaves are fermented, the lower the polyphenol content (See: "What's It Made Of?") and the higher the caffeine content. Green tea has the highest polyphenol content while black tea has roughly 2 - 3 times the caffeine content of green tea.

What's It Made Of?

Researchers think the health-giving properties of green tea are mostly due to polyphenols, chemicals with potent antioxidant properties. In fact, the antioxidant effects of polyphenols seem to be greater than vitamin C. The polyphenols in green tea also give it a somewhat bitter flavor.
Polyphenols contained in teas are classified as catechins. Green tea contains six primary catechin compounds: catechin, gallaogatechin, epicatechin, epigallocatechin, epicatechin gallate, and apigallocatechin gallate (also known as EGCG). EGCG is the most studied polyphenol component in green tea and the most active.
Green tea also contains alkaloids including caffeine, theobromine, and theophylline. They provide green tea's stimulant effects. L-theanine, an amino acid compound found in green tea, has been studied for its calming effects on the nervous system.

Source: University of Maryland Medical study of Green tea and Stomach cancer.

Green tea

Source:  University of Maryland Medical study of Green tea and Stomach cancer.

 

Casteas offers the best custom tea blends and the best organic tea blends because we blend just before shipping, the best teas for headaches also the best teas for weight loss if that is one of your goals, are fresh Casteas.  We would love to trade links with likeminded people dedicated to the same Ideals as Casteas we look forward to your friendships.

Tea has been cultivated for centuries, beginning in India and China. Today, tea is the most widely consumed beverage in the world, second only to water. Hundreds of millions of people drink tea, and studies suggest that green tea (Camellia sinesis) in particular has many health benefits.
There are three main varieties of tea -- green, black, and oolong. The difference is in how the teas are processed. Green tea is made from unfermented leaves and reportedly contains the highest concentration of powerful antioxidants called polyphenols. Antioxidants are substances that fight free radicals -- damaging compounds in the body that change cells, damage DNA, and even cause cell death. Many scientists believe that free radicals contribute to the aging process as well as the development of a number of health problems, including cancer and heart disease. Antioxidants such as polyphenols in green tea can neutralize free radicals and may reduce or even help prevent some of the damage they cause.
In traditional Chinese and Indian medicine, practitioners used green tea as a stimulant, a diuretic (to help rid the body of excess fluid), an astringent (to control bleeding and help heal wounds), and to improve heart health. Other traditional uses of green tea include treating gas, regulating body temperature and blood sugar, promoting digestion, and improving mental processes.
Green tea has been extensively studied in people, animals, and laboratory experiments. Results from these studies suggest that green tea may help treat the following health conditions:
Atherosclerosis
Clinical studies that look at populations of people indicate that the antioxidant properties of green tea may help prevent atherosclerosis, particularly coronary artery disease. Population-based studies are studies that follow large groups of people over time or studies that compare groups of people living in different cultures or with different diets.
Researchers aren't sure why green tea reduces the risk of heart disease by lowering cholesterol and triglyceride levels. Studies show that black tea has similar effects. In fact, researchers estimate that the rate of heart attack decreases by 11% with consumption of 3 cups of tea per day.
In May 2006, however, the U.S. Food and Drug Administration (FDA) rejected a petition from teamakers to allow tea labels to claim that green tea reduces the risk of heart disease. The FDA concluded that there is no credible evidence to support that claim.
High cholesterol
Research shows that green tea lowers total cholesterol and raises HDL ("good") cholesterol in both animals and people. One population-based clinical study found that men who drink green tea are more likely to have lower total cholesterol than those who do not drink green tea.
Results from one animal study suggest that polyphenols in green tea may block cholesterol from being absorbed in the intestine and also help the body get rid of cholesterol. In another small study of male smokers, researchers found that green tea significantly reduced blood levels of harmful LDL cholesterol.
Cancer
Several population-based clinical studies have shown that both green and black teas may help protect against cancer. For example, cancer rates tend to be low in countries such as Japan where people regularly consume green tea. However, it is not possible to know for sure from these population-based studies whether green tea actually prevents cancer in people.
Early clinical studies suggest that the polyphenols in tea, especially green tea, may play an important role in the prevention of cancer. Researchers also believe that polyphenols help kill cancerous cells and stop them from growing.
Bladder cancer. Only a few clinical studies have examined the relationship between bladder cancer and drinking tea. In one study that compared people with and without bladder cancer, researchers found that women who drank black tea and powdered green tea were less likely to develop bladder cancer. A follow-up clinical study by the same group of researchers revealed that people with bladder cancer -- particularly men -- who drank green tea had a better 5-year survival rate than those who did not.
Breast cancer. Clinical studies in animals and test tubes suggest that polyphenols in green tea inhibit the growth of breast cancer cells. In one study of 472 women with various stages of breast cancer, researchers found that women who drank the most green tea had the least spread of cancer. It was especially true in premenopausal women in the early stages of breast cancer. They also found that women with early stages of the disease who drank at least 5 cups of tea every day before being diagnosed with cancer were less likely to have the cancer come back after they finished treatment. However, women with late stages of breast cancer had little or no improvement from drinking green tea.
There is no clear evidence one way or the other about green tea and breast cancer prevention. In one very large study, researchers found that drinking tea, green or any other type, was not associated with a reduced risk of breast cancer. However, when the researchers broke down the sample by age, they found that women under the age of 50 who consumed 3 or more cups of tea per day were 37% less likely to develop breast cancer compared to women who didn't drink tea.
Ovarian cancer. In a clinical study done with ovarian cancer patients in China, researchers found that women who drank at least one cup of green tea per day lived longer with the disease than those who didn’t drink green tea. In fact, those who drank the most tea, lived the longest. But other studies found no beneficial effects.
Colorectal cancer. Clinical studies on the effects of green tea on colon or rectal cancer have showed conflicting results. Some studies show decreased risk in those who drink the tea, while others show increased risk. In one study, women who drank 5 or more cups of green tea per day had a lower risk of colorectal cancer compared to non-tea-drinkers. There was no protective effect for men, however. Other studies show that drinking tea regularly may reduce the risk of colorectal cancer in women. More research is needed before researchers can recommend green tea for the prevention of colorectal cancer.
Esophageal cancer. Studies in laboratory animals have found that green tea polyphenols inhibit the growth of esophageal cancer cells. However, studies in people have produced conflicting findings. For example, one large-scale population-based clinical study found that green tea offered protection against the development of esophageal cancer, particularly among women. Another population-based clinical study found just the opposite -- green tea consumption was associated with an increased risk of esophageal cancer. In fact, the stronger and hotter the tea, the greater the risk. Given these conflicting results, more research is needed before scientists can recommend green tea for the prevention of esophageal cancer.
Lung cancer. While green tea polyphenols have been shown to inhibit the growth of human lung cancer cells in test tubes, few clinical studies have looked at the link between drinking green tea and lung cancer in people. And even these studies have been conflicting. One population-based study found that Okinawan tea -- similar to green tea but partially fermented -- was associated with lower lung cancer risk, particularly among women. But a second clinical study found that green tea and black tea increased the risk of lung cancer. More studies are needed before researchers can draw any conclusions about green tea and lung cancer.
Pancreatic cancer. In one large-scale clinical study researchers compared green tea drinkers with non-drinkers and found that those who drank the most tea were less likely to develop pancreatic cancer. This was particularly true for women -- those who drank the most green tea were half as likely to develop pancreatic cancer as those who drank less tea. Men who drank the most tea were 37% less likely to develop pancreatic cancer.
However, it is not clear from this population-based study whether green tea is solely responsible for lowering pancreatic cancer risk. More studies in animals and people are needed before researchers can recommend green tea for the prevention of pancreatic cancer.
Prostate cancer. Laboratory studies have found that green tea extracts prevent the growth of prostate cancer cells in test tubes. In a large clinical study in Southeast China researchers found that the risk of prostate cancer went down with increasing frequency, duration and quantity of green tea consumption. However, both green and black tea extracts also stimulated genes that cause cells to be less sensitive to chemotherapy drugs. People who are undergoing chemotherapy should ask their doctors before drinking green or black tea, or taking tea supplements.
Skin cancer. The main polyphenol in green tea is epigallocatechin gallate (EGCG). Scientific studies suggest that EGCG and green tea polyphenols have anti-inflammatory and anticancer properties that may help prevent the development and growth of skin tumors.
Stomach cancer. Laboratory studies have found that green tea polyphenols inhibit the growth of stomach cancer cells in test tubes, but studies in people have been less conclusive. In two studies that compared green tea drinkers with non-drinkers, researchers found that people who drank tea were about half as likely to develop stomach cancer and stomach inflammation as those who did not drink green tea. However, a clinical study with more than 26,000 men and women in Japan found no association between green tea and stomach cancer risk. Some studies even suggest that green tea may increase the risk of stomach cancer.
More clinical studies are underway to see whether green tea helps reduce the risk of stomach cancer.
Inflammatory Bowel Disease (IBD)
Green tea may help reduce inflammation associated with Crohn's disease and ulcerative colitis, the two types of IBD. If green tea proves to help prevent colon cancer, it would also help those with IBD because they are at higher risk for colon cancer.
Diabetes
Green tea has been used traditionally to control blood sugar levels. Animal studies suggest that green tea may help prevent the development of type 1 diabetes and slow the progression once it has developed. In people with type 1 diabetes, their bodies make little or no insulin, which helps convert glucose or sugar into energy. Green tea may help regulate glucose in the body.
A few small clinical studies have found that taking a green tea extract daily lowered the hemoglobin A1c level in people with borderline diabetes.
Liver disease
Population-based clinical studies have shown that men who drink more than 10 cups of green tea per day are less likely to develop liver problems. Green tea also seems to protect the liver from the damaging effects of toxic substances such as alcohol. Animal studies have shown that green tea helps protect against liver tumors in mice.
Results from several animal and human studies suggest that one of the polyphenols in green tea, known as catechin, may help treat viral hepatitis, an inflammation of the liver. In these studies, catechin was used by itself in very high amounts. It is not clear whether green tea, which has a lower concentration of catechins, would have the same benefits.
10 cups of green tea a day could cause problems because of the high level of caffeine consumed. Ask your doctor about the best way to include green tea in your treatment.
Weight loss
Clinical studies suggest that green tea extract may boost metabolism and help burn fat. One study found that the combination of green tea and caffeine improved weight loss and maintenance in people who were overweight and moderately obese. Some researchers think that substances in green tea known as catechins are responsible for the herb's fat-burning effect.
Other uses
One small study found that drinking green tea helped prevent dental cavities. More studies need to be done. Green tea may also be useful in inflammatory diseases, such as arthritis. Research suggests that green tea may help arthritis by reducing inflammation and slowing the breakdown of cartilage. Chemicals in green tea may also be help treat genital warts and prevent symptoms of colds and flu. Studies also show that drinking green tea is associated with reduced risk of dying from any cause.

Plant Description

Green, black, and oolong tea are all derived from the leaves of the Camellia sinensis plant. Originally cultivated in East Asia, this plant grows as large as a shrub or tree. Today, Camellia sinensis grows throughout Asia and parts of the Middle East and Africa.
People in Asian countries more commonly consume green and oolong tea while black tea is most popular in the United States. Green tea is prepared from unfermented leaves, the leaves of oolong tea are partially fermented, and black tea is fully fermented. The more the leaves are fermented, the lower the polyphenol content (See: "What's It Made Of?") and the higher the caffeine content. Green tea has the highest polyphenol content while black tea has roughly 2 - 3 times the caffeine content of green tea.

What's It Made Of?

Researchers think the health-giving properties of green tea are mostly due to polyphenols, chemicals with potent antioxidant properties. In fact, the antioxidant effects of polyphenols seem to be greater than vitamin C. The polyphenols in green tea also give it a somewhat bitter flavor.
Polyphenols contained in teas are classified as catechins. Green tea contains six primary catechin compounds: catechin, gallaogatechin, epicatechin, epigallocatechin, epicatechin gallate, and apigallocatechin gallate (also known as EGCG). EGCG is the most studied polyphenol component in green tea and the most active.
Green tea also contains alkaloids including caffeine, theobromine, and theophylline. They provide green tea's stimulant effects. L-theanine, an amino acid compound found in green tea, has been studied for its calming effects on the nervous system.