BOSTON (PasseportSanté.net) September 30, 2009. The beneficial effects of tea cannot be denied: cardiovascular protection, cancer prevention, weight loss and even treatment of the human papillomavirus (HPV). On the occasion of the World Tea Expo1, Mark Blumenthal, Founder and Director of the American Botanical Council2, provided an update on recent research on tea and tea extracts.
“It is on the cardiovascular protection side that the data are the most convincing,” said Mark Blumenthal. As for the anticancer effect of tea and its components, research is on the rise, and the evidence varies depending on the type of cancer. “
Heart side
Epidemiological data clearly points to a protective effect of tea3.4, on heart health, but clinical studies are shedding light on how.
Mark Blumenthal, for example, mentioned a trial indicating that the consumption of green tea has a beneficial effect on the functioning of the arteries (endothelial function)5. “In another study, the consumption of a green tea extract reduced several risk factors for cardiovascular disorders as early as the third week of the trial,” he continued. Compared to placebo, the supplement slightly reduced blood pressure, LDL cholesterol, oxidative stress, and a marker of inflammation6. The extract contained 100 mg of theanine and 200 mg of decaffeinated green tea catechins. Catechins are considered to be the main active antioxidants in tea.
Studies on green tea are more numerous and more convincing, those on black tea having given contradictory results7.8. Note that green tea and black tea contain roughly the same percentage of antioxidants initially, but those in green tea are much better absorbed in the intestine. Green tea therefore has superior antioxidant activity.
Cancer side
There are many epidemiological studies available on the link between green tea consumption and cancer prevention. However, the researchers’ conclusions diverge, which makes the overall picture less convincing than in the case of cardiovascular disease.9. “It is in the case of gastrointestinal cancers that the data are the most solid, even if, again, they are not unanimous10 », Said Mark Blumenthal.
Interestingly, consuming 5 or more cups of green tea per day would reduce the risk of oral and throat cancer, compared to consuming just one cup. It is a large Japanese cohort study (65,000 subjects followed for 10 years) that comes to this conclusion.11. “According to the authors, this protective effect is attributable to the fact that green tea prevents cavities, gingivitis and periodontitis”, explained the speaker.
Slimming side
“A growing body of evidence points to an anti-obesity effect of tea and tea catechins, a potential benefit that could benefit many North Americans,” said Mark Blumenthal. But in this area, the Food and Drug Administration is very cautious, as there have been several cases of misleading claims. “
According to 2 recent trials, tea, as an extract, may increase weight loss in people on a diet12.13.
Prescription green tea to treat HPV
In 2007, the US Food and Drug Administration approved a cream containing a concentrate of green tea catechins for the external treatment of genital warts. This sexually transmitted disease is caused by the human papillomavirus (HPV). “This product is the first herbal medicine to be approved by the FDA in 50 years,” said Mark Blumenthal. Note that this is a prescription drug14.
The study that served as the basis for the approval of Veregen® was conducted in Germany on 252 subjects with genital warts15. Two other conclusive trials have since been published, including one in Germany (2008, 503 subjects)16 and the other in Argentina (2009, 1,004 subjects)17.
“This drug comes from a green tea cultivated in China, the catechins are extracted in Japan and it is a German company which manufactures it: a beautiful illustration of the world market in which we live”, concluded Mark Blumenthal.
|
To read other news from our coverage of the World Tea Expo: Discover the theanine in tea: relaxing and immunizing! The carbon footprint of food: soon on a label near you? |
Françoise Ruby – PasseportSanté.net
1. The World Tea Expo is a trade fair for retailers and industry. The biggest event is held annually in Las Vegas and brings together hundreds of exhibitors and thousands of visitors. The Boston Expo was much smaller, but several lectures were presented there. www.worldteaexpo.com.
2. This organization, dedicated to the dissemination of accurate and reliable information on medicinal plants, celebrated its 20th anniversary in 2008. Mark Blumenthal is also editor-in-chief of the quarterly review Herbalgram, published by the American Botanical Council.
3. Green tea consumption and mortality among Japanese elderly people: the prospective Shizuoka elderly cohort. Suzuki E, Yorifuji T, et al. Ann Epidemiol. 2009 Oct; 19 (10): 732-9.
4. Green and black tea consumption and risk of stroke: a meta-analysis. Arab L, Liu W, Elashoff D. Stroke. 2009 May; 40 (5): 1786-92. Review.
5. The acute effect of green tea consumption on endothelial function in healthy individuals. Alexopoulos N, Vlachopoulos C, et al. Eur J Cardiovasc. Prev Rehabil. 2008 Jun; 15 (3): 300-5.
6. Standardized capsule of Camellia sinensis lowers cardiovascular risk factors in a randomized double-blind, placebo-controlled study. Nantz MP, Rowe CA, et al. Nutrition 2009 Feb; 25 (2): 147-154.
7. A 6-month randomized pilot study of black tea and cardiovascular risk factors. Mukamal KJ, MacDermott K, et al. Am Heart J. 2007 Oct; 154 (4): 724.e1-6. Full text: www.pubmedcentral.nih.gov
8. Steptoe A, Gibson EL, Vuononvirta R et al. The effects of chronic tea intake on platelet activation and inflammation: a double-blind placebo controlled trial. Atherosclerosis. 2007 Aug; 193 (2): 277-82.
9. Green tea (Camellia sinensis) and cancer prevention: a systematic review of randomized trials and epidemiological studies. Liu J, Xing J, Fei Y. Chin Med. 2008 Oct 22; 3:12.
10. Green tea consumption and risk of stomach cancer: a meta-analysis of epidemiologic studies. Myung SK, Bae WK, et al. Int J Cancer. 2009 Feb 1; 124 (3): 670-7. Erratum in: Int J Cancer. 2009 Mar 15; 124 (6): 1496.
11. A prospective study of green tea consumption and oral cancer incidence in Japan. Ide R, Fujino Y, et al; JACC Study Group. Ann Epidemiol. 2007 Oct; 17 (10): 821-6.
12. Greenselect Phytosome as an adjunct to a low-calorie diet for treatment of obesity: a clinical trial. Di Pierro F, Menghi AB, et al. Altern Med Rev. 2009 Jun; 14 (2): 154-60.
13. Green tea catechin consumption enhances exercise-induced abdominal fat loss in overweight and obese adults. Maki KC, Reeves MS. et al. J Nutr. February 2009; 139 (2): 264-270.
14. Currently, this drug is marketed in the United States and some European countries. It is not available in Canada.
15. A randomized, double-blind, four-arm parallel-group, placebo-controlled Phase II / III study to investigate the clinical efficacy of two galenic formulations of Polyphenon E in the treatment of external genital warts. Gross G, Meyer KG, et al. J Eur Acad Dermatol Venereol. 2007 Nov; 21 (10): 1404-12.
16. Topical Polyphenon E in the treatment of external genital and perianal warts: a randomized controlled trial. Stockfleth E, Beti H, Orasan R et al. Br J Dermatol. 2008 Jun; 158 (6): 1329-38.
17. Polyphenon E (R): a new treatment for external anogenital warts. Tatti S, Stockfleth E, et al. Br J Dermatol. 2009 Jul 27.
