绿茶保健作用研究

[目的]探讨绿茶保健作用。[方法]应用722分光光度仪测定绿茶中茶多酚含量,应用原子吸收分光光度仪测定微量元素含量及溶出率。[结果](1)绿茶等级越高其氨基酸、茶多酚的含量越高,锌含量亦越高。不同等级间茶多酚、微量元素锌含量差别甚大,茶多酚含量高者达36.2%,低者仅10.9%。锌含量高者达53.2μg/g,低者仅35.25μg/g。(2)铜、铁含量不高且品种间差别不大。(3)锰、氟、铝含量则随茶叶等级降低而升高,且品种间含量差别甚大。(4)5种绿茶中锌的溶出率均较高,达79.95%～88.26%,铜达70.6%～92.89%,氟达72.75%～95.63%,铁多为35%左右,锰36.08%～44.66%,铝8.81%～51.69%。[结论]高级别绿茶具有保健作用,低级别绿茶无益于健康。     

绿茶及其有效成分对肾性高血压大鼠左室肥厚抑制作用的研究

目的研究绿茶及其提取物对肾性高血压大鼠左室肥厚的抑制作用机制。方法雄性Wistar大鼠160只,体重180~220g,随机分为5组,建立二肾一夹法大鼠肾性高血压左室肥厚模型:假手术组(SHAM)和手术组(2K1C)正常饮水;手术+绿茶组(2K1C+GT)饮用2%绿茶水;手术+茶多酚组(2K1C+TP)饮用0.1%茶多酚水;手术+EGCG组(2K1C+EGCG)饮用0.05%EGCG水,术后即给予不同浓度的绿茶及其提取物,持续8周直至实验结束。结果与假手术组比较,手术组和各饮茶组血压、左心室与体重比值(LVW/BW)和左心室壁厚度(LVWT)均显著升高(P<0.01)。而与手术组相比,不同浓度的绿茶及其有效成分(2%绿茶、0.1%茶多酚、0.05%EGCG)左心室重/体重(LVW/BW)、左心室壁厚度显著降低,抗氧化酶(SOD和GSH-Px)的活性升高,活性氧自由基(ROS)以及Ras和ERK1/2蛋白表达降低,但对大鼠收缩压无显著性影响。结论绿茶及其提取物对肾性高血压大鼠左室肥厚有抑制作用,其机制可能是由于茶及其有效成分具有抗氧化活性,能够清除ROS,以及对Ras-MAPK信号传导通路的调控有关。     

绿茶多酚抗紫外线作用机制研究进展

研究表明,长期受到阳光中紫外线的照射不仅会引起皮肤红斑、晒伤,还会造成体内的氧化应激及免疫抑制,甚至导致皮肤肿瘤的发生.近年来,绿茶茶叶中主要活性成分绿茶多酚的健康效应越来越受到人们的关注.许多研究指出,绿茶多酚具有促进微循环、抗氧化、抗炎症以及抗癌的作用.但在国内,绿茶多酚抗紫外线方面的研究仍然较少.本文从绿茶多酚抗炎、抗氧化、促进DNA修复等几个方面对其抗紫外线的机制作一综述,并且对含有绿茶多酚的防晒用品的实际应用前景进行展望.     

营养

052284 葡多酚对大鼠DNA氧化损伤的防护作用研究；052285 绿茶、乌龙茶、红茶的茶多糖组成、抗氧化及降血糖作用研究；052286 茶多酚影响同型半胱氨酸对内皮细胞的作用；052287 连翘叶茶抗氧化抗衰老作用的实验研究；052288 视黄酸对人胸腺细胞成熟分化影响及其作用机制；     

绿茶之最

茶有提神作用人人皆知,你又可知道绿茶能够让你“心”壮力健?原来,绿茶的茶多酚含量颇高,有助降低人体内的高血脂和高血压,从而保障心脏和血管健康。它又可以增强身体的抵抗力,预防流感的感染,令人饮用后拥有强健的体魄。 瘦身养颜茶 绿茶中的芳香油化合物有溶解脂肪的作用,防止脂肪积滞;它所含的维他命B1和维他命C都能够促进胃液分泌,帮助消化和消脂。绿茶蕴含的茶多酚和维他命C,会发挥抗氧化、延缓衰老的功效,而     

绿茶对中枢神经保护作用研究进展

茶是世界上尤其是亚洲人广泛饮用的饮料。根据发酵程度不同，茶可以分成绿茶（非发酵）、乌龙茶（部分发酵）、红茶（完全发酵）。绿茶中的主要生物活性成分是茶多酚。茶多酚是一类存在于茶树中的多羟基酚类化合物，俗名茶单宁、茶鞣质。茶多酚的主要成分为黄烷醇类，通常称为儿茶素，占绿茶干重的25％-35％。儿茶素家族主要包括8种化合物即表没食子儿茶素表没食子酸酯（EGCG）、表没食子儿茶素（EGC）、表儿茶素表没食子酸酯（ECG）、表儿茶素（EC）等，其中EGCG含量最高。     

青砖茶与绿茶对大鼠脂代谢和抗氧化作用的比较研究

目的分析了青砖茶及绿茶主要生化成分含量及其对大鼠减肥和抗氧化作用。方法选用2种贮藏时间的青砖茶和普通绿茶测定其主要化学成分,选取雄性Wistar大鼠60只,体重为80±5g,随机分为6组,每组10只。空白对照组和模型对照组每天灌胃蒸馏水;阳性对照组每天灌胃Orlistat 0.04g/kg·bw,1年砖剂量组、10年砖剂量组、绿茶剂量组每天灌胃1.5g/kg·bw的相应茶汤。除空白对照组喂饲普通饲料外,其它5组均喂饲高脂营养饲料,试验期6w。定期称体重,测体长,实验结束后颈动脉取血,测血脂及其抗氧化指标,观测大鼠体内脂肪沉着及脏器变化情况。结果 10年青砖茶茶多糖、茶褐素含量最高,其它成分含量最低,而绿茶茶多糖、茶褐素含量最低,其它成分含量最高。青砖茶、绿茶都能显著降低大鼠体重、Lee’s指数、脂肪系数及血脂水平,能显著提高血清HDL-C含量及血清、肝脏SOD、GSH-PX活性,降低血清和肝脏MDA水平,有效减小脂肪细胞直径。其中,青砖茶的效果优于绿茶,10年砖茶优于1年砖茶。结论青砖茶较绿茶更具有减肥降脂、抗氧化作用。     

茶多酚对老龄大鼠血脂及体内抗氧化能力的影响

目的研究茶多酚的降血脂及抗氧化能力。方法以老龄ＳＤ大鼠分设对照组、２％和１％茶多酚３组，共饲养６周检测生化指标。结果茶多酚能降低大鼠血清胆固醇含量，提高ＨＤＬ－Ｃ／ＴＣ比值及显著降低血清脂质过氧化物含量，２％茶多酚组大鼠的红细胞超氧化物岐化酶活性显著高于对照组。对缺铁性贫血大鼠进行４周恢复试验，茶多酚组和对照组大鼠的血红蛋白和红细胞游离原卟啉含量差异无显著性。结论提示茶多酚能增强老龄大鼠体内抗氧化能力，实验剂量的茶多酚对铁在机体内的生物利用并无不良影响。     

在茶中加入健康“佐料”

绿茶＋柠檬——护心 绿茶富含茶多酚类化合物,具有预防癌症、改善心血管健康、减肥、抵御电离辐射等多种保健功能。柠檬富含维生素C,可预防黑色素沉淀,也有抗氧化作用,预防心血管疾病。绿茶加柠檬能提高人体对茶多酚化合物的吸收率。     

高效液相色谱法测定茶多酚中儿茶素组成及咖啡因含量

茶多酚(ｇｒｅｅｎｔｅａｐｏｌｙｐｈｅｎｏｌｓ,ＧＴＰ)是从绿茶中分离提纯的天然多酚类复合体。大量研究表明,它具有很强的抗氧化活性[1]。ＧＴＰ中的主体成分儿茶素是其活性成分,由于各儿茶素的抗氧化能力不尽相同,为了对各儿茶素的含量变化有较深入的了解,我们采用高效液相色谱法对茶多酚中6种儿茶素及咖啡因进行含量测定。一、材料与方法1仪器与试剂:岛津ＬＣ4Ａ高效液相色谱仪,ＳＰＤ2ＡＳ紫外检测器,ＣＲ2ＡＸ数据处理机。对照品:表没食子儿茶素(ＥＧＣ)、儿茶素(ＤＬＣ)、表没食子基儿茶素没食子酸酯(ＥＧＣＧ)、表儿茶素(ＥＣ)、…     

茶叶及茶饮料中儿茶素和咖啡因的多组分HPLC分析方法

目的　建立茶叶及茶饮料中儿茶素和咖啡因多组分HPLC测定方法。方法　以水 -乙醇 (3∶7)为提取剂 ,超声提取 ,提取液离心后 ,采用C1 8柱分离 ,HPLC- UV检测。以 0 . 1%H3PO4 的甲醇溶液为流动相A ,0 .1%H3PO4 的水溶液为流动相B ,进行梯度洗脱 ,流速为 1ml min,检测波长为 2 10nm。结果　在给定的浓度范围内 ,各儿茶素组分和咖啡因的峰面积与其相应浓度呈现良好的线性相关 ,r>0. 999。添加已知儿茶素含量的茶粉回收试验结果显示 ,各组分儿茶素及咖啡因的平均回收率为 6 1. 7%～ 117. 4 % ,相对标准差 <10 %。结论　本方法分离度好 ,灵敏度高 ,准确快速 ,为研究儿茶素在机体内的吸收利用提供了可靠手段。     

Investigation of the Oral Retention of Tea Catechins in Humans: An Exploratory Interventional Study

Green tea catechin ingestion or gargling exhibit anti-viral activity against upper respiratory infection. We hypothesized that retention in the oral cavity could improve the anti-viral effects of catechins. The present study investigated the oral retention of catechins in humans and the effect of catechin beverage viscosity on oral retention. Two intervention studies with different test beverages, beverage-C (40 mL, containing 73.4 mg of catechins) and beverage-XT (40 mL, beverage-C containing 100 mg xanthan gum) were conducted in 20 healthy volunteers (mean age 38.7 years). Catechin concentrations were measured in buccal mucosa samples collected at 10 min, 40 min, and 60 min after ingesting test beverages, and the catechin variability of the tissue after intake was compared between test beverages. As a result, the mean (SEM) concentrations of EGCG were 99.9 (27.2), 58.2 (16.6), and 22.3 (5.7) ng/mg-mucosa at 10, 40, and 60 min, respectively, after ingestion of beverage-XT. Similarly, the catechin concentrations were 86.1 (20.3), 32.2 (5.3), and 27.8 (5.9) ng/mg-mucosa after ingestion of beverage-C. The total retention volume over 60 min tended to be slightly higher after ingestion of beverage-XT, though the difference was not statistically significant. Additional studies are needed to confirm the effect of xanthan gum on improving oral retention of catechins.     

Assessment of antioxidant capacity and phenolic content of selected commercial beverages

This study was aimed at assessing the antioxidant capacity and phenolic (free, bound, and total) contents in selected commercial beverages. Three different types of beverages commonly available in Malaysian supermarkets namely, cocoa, coffee and tea were selected. Phenolic contents were determined using a Folin-Ciocalteu assay. Antioxidant capacity (ferric reducing power and scavenging activity) was determined using FRAP and TEAC assays. Based on analysis of variance, coffee showed the highest amount of free phenolic compounds and antioxidant capacity compared to cocoa and tea (p < 0.05). The major phenolic compound detected in coffee was chlorogenic acid. Cocoa showed higher phenolic content than tea. However, cocoa and tea have similar catechin content and possessed comparable antioxidant capacity. The free phenolic content in the three beverages was found to be highly correlated with antioxidant capacity. In addition, moderate correlation was observed between total phenolic content and antioxidant capacity. On the other hand, there was no significant contribution of bound phenolic compounds towards antioxidant capacity. The contribution of antioxidant capacity in these beverages could be due to phenolic compounds in the free form. The study indicated that the beverages studied possessed varying degrees of antioxidant capacity and phenolic contents.     

The relation between single/double or repeated tea catechin ingestions and plasma antioxidant activity in humans

OBJECTIVE: The purpose of this study was to investigate the effects of single/double or repeated intake of a normal amount of tea catechin on plasma catechin concentrations and antioxidant activity in young women. DESIGN: First, after an overnight fast, five healthy subjects were given water or single/double dose(s) of tea polyphenol extract (164 mg tea catechins containing 61% epigallocatechin gallate in 190 ml water). Blood samples were taken before and 30, 60 and 180 min after the ingestion. Second, 16 healthy subjects ingested the tea polyphenol extract three times a day at mealtimes for 7 days followed by withdrawal of tea polyphenol extract for 7 days. Blood samples were taken before and after ingestion, and 7 days after the withdrawal of tea catechin. Subjects were prohibited from drinking any beverages containing polyphenols or antioxidant supplements during the study period. Catechin and other antioxidant concentrations in the plasma were measured, and changes in antioxidant activity were evaluated by ferric reducing ability of plasma assay. RESULTS: Single/double ingestion of tea polyphenol extract did not cause an increase in the antioxidant activity. There was no also change in antioxidant activity after the ingestion of tea polyphenol extract for 7 days. Plasma-free epigallocatechin gallate concentration remained at the pre-study level; however, the plasma FRAP value decreased significantly at 7 days after the withdrawal of tea polyphenol extract. Decreases in endogenous antioxidants in the plasma, including vitamin C and bilirubin, were also observed 7 days after withdrawal of tea polyphenol. CONCLUSIONS: The results suggest that continuous daily intake of tea catechins affects the concentrations of endogenous antioxidants in the plasma and has the potential to maintain total antioxidant activity.     

Catechin intake might explain the inverse relation between tea consumption and ischemic heart disease: the Zutphen Elderly Study

BACKGROUND: Epidemiologic studies suggest that tea consumption may reduce the risk of cardiovascular diseases, but results are inconsistent. Catechins, which belong to the flavonoid family, are the main components of tea and may be responsible for the alleged protective effect. Taking catechin sources other than tea into account might clarify the reported associations. OBJECTIVE: The objective was to evaluate the association between catechin intake and the incidence of and mortality from ischemic heart disease and stroke. DESIGN: We evaluated the effect of a high catechin intake by using data from the Zutphen Elderly Study, a prospective cohort study of 806 men aged 65-84 y at baseline in 1985. RESULTS: The mean (+/-SD) catechin intake at baseline was 72 +/- 47.8 mg, mainly from black tea, apples, and chocolate. A total of 90 deaths from ischemic heart disease were documented. Catechin intake was inversely associated with ischemic heart disease mortality; the multivariate-adjusted risk ratio in the highest tertile of intake was 0.49 (95% CI: 0.27, 0.88; P for trend: 0.017). After multivariate adjustment, catechin intake was not associated with the incidence of myocardial infarction (risk ratio in the highest tertile of intake: 0.70; 95% CI: 0.39, 1.26; P for trend: 0.232). After adjustment for tea consumption and flavonol intake, a 7.5-mg increase in catechin intake from sources other than tea was associated with a tendency for a 20% reduction in ischemic heart disease mortality risk (P = 0.114). There was no association between catechin intake and stroke incidence or mortality. CONCLUSION: Catechins, whether from tea or other sources, may reduce the risk of ischemic heart disease mortality but not of stroke.     

Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages

The effects of different polyphenol-containing beverages on Fe absorption from a bread meal were estimated in adult human subjects from the erythrocyte incorporation of radio-Fe. The test beverages contained different polyphenol structures and were rich in either phenolic acids (chlorogenic acid in coffee), monomeric flavonoids (herb teas, camomile (Matricaria recutita L.), vervain (Verbena officinalis L.), lime flower (Tilia cordata Mill.), pennyroyal (Mentha pulegium L.) and peppermint (Mentha piperita L.), or complex polyphenol polymerization products (black tea and cocoa). All beverages were potent inhibitors of Fe absorption and reduced absorption in a dose-dependent fashion depending on the content of total polyphenols. Compared with a water control meal, beverages containing 20-50 mg total polyphenols/serving reduced Fe absorption from the bread meal by 50-70%, whereas beverages containing 100-400 mg total polyphenols/serving reduced Fe absorption by 60-90%. Inhibition by black tea was 79-94%, peppermint tea 84%, pennyroyal 73%, cocoa 71%, vervain 59%, lime flower 52% and camomile 47%. At an identical concentration of total polyphenols, black tea was more inhibitory than cocoa, and more inhibitory than herb teas camomile, vervain, lime flower and pennyroyal, but was of equal inhibition to peppermint tea. Adding milk to coffee and tea had little or no influence on their inhibitory nature. Our findings demonstrate that herb teas, as well as black tea, coffee and coca can be potent inhibitors of Fe absorption. This property should be considered when giving dietary advice in relation to Fe nutrition.     

Knowledge,perceptions, and behaviors of adults concerning nonalcoholic beverages suggest some lack of comprehension related to sugars

Key recommendations in the 2010 Dietary Guidelines for Americans and US Department of Agriculture's MyPlate are to reduce the intake of added sugars, particularly from sugar-sweetened beverages, and drink water instead of “sugary” beverages. However, little is known about consumer knowledge, perceptions, and behaviors regarding sugars in beverages. We hypothesized that consumers would have limited or inaccurate knowledge of the sugars in beverages and that their beverage consumption behaviors would not reflect their primary concerns related to sugars in beverages. An online survey was completed by 3361 adults 18 years and older residing throughout the United States. Water was consumed in the highest amounts followed by (in descending amounts) other beverages (includes coffee and tea), added sugar beverages, milk, diet drinks, and 100% fruit juice and blends. Participants primarily associated the term “sugary” with beverages containing added sugars; however, almost 40% identified 100% fruit juice as sugary. Some participants misidentified the types of sugars in beverages, particularly with respect to milk and 100% fruit juices. Generally, beverage choices were consistent with stated concerns about total, added, or natural sugars; however, less than 40% of participants identified added sugars as a primary concern when choosing beverages despite public health recommendations to reduce the intake of added sugars and sugar-sweetened beverages. Results suggest that there may be a considerable level of consumer misunderstanding or confusion about the types of sugars in beverages. More consumer research and education are needed with the goal of helping consumers make more informed and healthy beverage choices.     

Iron absorption and phenolic compounds: importance of different phenolic structures

The phenolic compounds (phenolic monomers, polyphenols, tannins) are considered to interfere with iron absorption by complex formation with iron in the gastro-intestinal lumen, making the iron less available for absorption. Very little is known about the extent to which different types of phenolic compounds of different size and chemical structure inhibit iron absorption. The relationship between iron absorption and the amount and type of phenolic compounds was studied by the extrinsic tag method. The aims of the studies were as follows: (i) To study the effect of small phenolic compounds with different hydroxylation patterns (gallic acid, catechin, chlorogenic acid) on iron absorption, (ii) To study the effect of different amounts of a hydrolysable tannin containing ten gallic acid residues (tannic acid) on iron absorption. (iii) To study the degree of inhibition of iron absorption by some foods and beverages (oregano, spinach, coffee and tea) in relation to their respective content of iron-binding phenolic groups, measured by a newly developed method. The inhibition of iron absorption by tannic acid was strongly dose-related. The smallest amount (5 mg) inhibited absorption by 20 per cent, 25 mg by 67 per cent and 100 mg by 88 per cent. Gallic acid inhibited iron absorption to the same extent as tannic acid, per mol galloyl groups, whereas no inhibition was observed when catechin was added to the test meal. Chlorogenic acid inhibited iron absorption to a lesser extent. Oregano and tea inhibited iron absorption in proportion to their respective content of galloyl groups, whereas the inhibitory effect of spinach was less marked. The inhibiting effect of coffee was explained mainly by its content of galloyl groups, but also by some other factor, probably chlorogenic acid. It is concluded that the content of iron-binding galloyl groups might be a major determinant of the inhibitory effect of phenolic compounds on iron absorption from the diet, whereas the phenolic catechol groups seem to be of minor importance. The results further suggest that the group of condensed tannins do not interfere with iron absorption.     

Roles for Epigallocatechin Gallate in Cardiovascular Disease and Obesity: An Introduction

After water, tea from Camellia sinensis is the most consumed beverage worldwide. Tea is rich in catechin flavonoids that possess an array of bioactivity including antioxidant, anti-inflammatory, apoptotic, and probiotic mechanisms of action that may contribute to some of the putative health benefits associated with tea intake. A substantial body of evidence indicates that tea and its principal catechin, epigallocatechin gallate (EGCG) may contribute to a reduction in the risk of cardiovascular disease. Recent studies suggest EGCG may also have a positive impact on glucose tolerance and thermogenesis with implications for an effect on the pathogenesis of type 2 diabetes mellitus and obesity, respectively. This introduction to a symposium on EGCG’s role in cardiovascular disease and obesity presented at the 2006 annual meeting of the American College of Nutrition provides a background on tea and tea flavonoids and their possible relationship to health promotion and disease prevention.