catechins (カテキン 兒茶素，又稱茶單寧，兒茶酚)

兒茶素（Catechin），又稱茶單寧，兒茶酚，是茶葉中黃烷醇類物質的總稱，兒茶素是茶多酚中最重要的一種，約占茶多酚含量的75%到80%，也是茶的苦澀味的來源之一。

兒茶素主要分為四種：表兒茶酚（epicatechin EC）、表沒食子兒茶酚（epigallocatechin EGC）、表兒茶酚沒食子酸（epicatechin gallate ECg）和表沒食子兒茶酚沒食子酸（epigallocatechin gallate EGCg）。

兒茶素具有以下作用：

• 抗氧化，消除自由基
• 預防蛀牙的作用。
• 抗菌
• 除臭

兒茶素也可以從茶葉中提取出來，作為食品添加劑。

[編輯] 參見

• 茶多酚
• 單寧酸

カテキンには実に多様な生理活性があることが報告されており、それらを列挙すると、血圧上昇抑制作用、血中コレステロール調節作用、血糖値調節作用、抗酸化作用、老化抑制作用、抗突然変異、抗癌、抗菌、抗う蝕、抗アレルギー作用などとなる。

チャ抽出物は1988年ごろより虫歯予防の食品コンセプトで産業的に使われるようになり、特に子供向けの菓子に利用されている。また茶カテキンの各種生理効果を特徴とした特定保健用食品が数点認可・販売されている。

カテキンの効果をわかりやすく説明するために、「菌に勝つ」→「勝て菌」という説明をしたことから、「カテキンは勝て菌から名付けられた」という誤解がある。

Sources of catechins

Catechins constitute about 25% of the dry weight of fresh tea leaf^[1], although total catechin content varies widely depending on clonal variation, growing location, seasonal/ light variation, and altitude. They are present in nearly all teas made from Camellia sinensis, including white tea, green tea, black tea and Oolong tea.

Catechins are also present in the human diet in chocolate^[2], fruits, vegetables and wine^[3] and are found in many other plant species^[4].

[edit] Health benefits of catechins

The health benefits of catechins have been studied extensively in humans and in animal models. Reduction in atherosclerotic plaques was seen in animal models.^[5] Reduction in carcinogenesis was seen in vitro.^[6]

Many studies on health benefits have been linked to the catechin content. According to Norman Hollenberg, professor of medicine at Harvard Medical School, epicatechin can reduce the risk of four of the major health problems: stroke, heart failure, cancer and diabetes. He studied the Kuna people in Panama, who drink up to 40 cups of cocoa a week, and found that the prevalence of the "big four" is less than 10%. He believes that epicatechin should be considered essential to the diet and thus classed as a vitamin.[1]Science Daily March 12, 2007

According to one researcher^[7] epigallocatechin-3-gallate is an antioxidant that helps protect the skin from UV radiation-induced damage and tumor formation.

Green tea catechins have also been shown to possess antibiotic properties due to their role in disrupting a specific stage of the bacterial DNA replication process^[8].

A study on green-tea catechins is reviewed here: http://www.sciencedaily.com/releases/2007/08/070810194923.htm