Finding suggests regular consumption could help reduce cardiovascular disease risk
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Washington, D.C., October 12, 1999 - Substances in green tea known as catechins can increase the antioxidant capacity of human plasma, which could help reduce cardiovascular disease risk, according to work published by Japanese researchers in the October issue of the Journal of Agricultural and Food Chemistry. The journal is a peer-reviewed publication of the American Chemical Society, the world's largest scientific society.
"We believe we have shown for the first time the course change of both green tea catechin levels in human plasma as well as human plasma lipid peroxide levels after oral green tea catechin supplementation, " said Teruo Miyazawa, Ph.D., biodynamic chemistry professor at the Tohoku University Graduate School of Life Science and Agriculture and the study's principal investigator.
Green tea is a very popular beverage in Japan and throughout many parts of the world. It has been linked in other studies to possible lowered risks from several forms of cancer
In the study, 18 healthy male subjects between the ages of 23 and 41 ingested green tea extracts in tablet form (including 254 milligrams of catechins per subject - one cup of green tea contains about 100 to 150 milligrams of catechin). All of the subjects avoided tea and tea-related beverages for 12 hours prior to the testing. Blood samples were taken one hour before and after the catechin ingestion.
Testing following the ingestion showed that catechin was incorporated into the subjects' plasma and that their phosphatidylcholine hydroperoxide (PC-OOH, a recognized marker of oxidative injury of plasma lipoproteins) levels were lowered as well. Plasma lipoprotein oxidation is generally recognized to be an important step in the formation of atherosclerotic plaques and subsequent cardiovascular disease, so lowered PC-OOH levels suggest a lowered risk of cardiovascular disease.
Miyazawa said two methodologies previously tested by his group allowed for a highly sensitive as well as a highly selective way to determine both plasma catechin and lipid peroxide levels, and that the findings certainly merit further consideration and study, given the worldwide prevalence of cardiovascular disease.
Miyazawa's study colleagues were: Kiyotaka Nakagawa, also of the Tohoku University Graduate School of Life Science and Agriculture; Manabu Ninomiya, Tsutomu Okubo, Nobuyuki Aoi, Lekh Raj Juneja, and Mujo Kim of the Taiyo Kagaku Company; and, Kenji Yamanaka, of the Sasakawa Clinic of Gastroenterology.
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