Epidemiological Evidence Linking Tea Consumption to Human Health: A Review

Tea has been widely consumed around the world for thousands of years and drinking tea is a daily habit for people of all ages. Tea is a major source of flavanoids, which have become well known as antioxidants. Tea also contains caffeine and theanine, which have been found to associate with health benefits. Many animal and epidemiological studies have been conducted to investigate the link between tea consumption and human health. However, common questions that arise about tea consumption include: whether all teas are the same, why drinking tea is linked with health benefits, how do the different ways of tea preparation impact on availability of tea components, how much and how long a person should consume tea to obtain health benefits, and whether there is any negative health effect associated with drinking tea. To answer these questions, this paper outlines the tea components and their link to human health, discusses major factors affecting availability of tea components in a tea cup, and reviews the latest epidemiological evidence linking tea consumption to human health.     

Beneficial effects of tea and its polyphenols against prostate cancer

Tea, next to water, is the most widely consumed beverage in the world. Depending upon the level of fermentation, tea can be categorized into three types: green (unfermented), oolong (partially fermented), and black (highly to fully fermented). In general, green tea has been found to be superior to black and oolong tea in terms of antioxidant and health promoting benefits owing to the higher content of (-)-epigallocatechin-3-gallate. Tea polyphenols comprise about one-third of the weight of the dried leaf, and they exhibit biochemical and pharmacological activities including antioxidant activities, inhibition of cell proliferation, induction of apoptosis, cell cycle arrest and modulation of carcinogen metabolism. Several studies demonstrate that most tea polyphenols exert their effects by scavenging reactive oxygen species (ROS) since excessive production of ROS has been implicated in the development of a variety of ailments including cancer of the prostate gland (CaP). Using cell culture and animal model systems, molecular targets for these remarkable beneficial effects of green tea drinking on CaP prevention and therapy have been defined. Geographical and case-control studies are showing that green tea drinking could afford CaP chemopreventive effects in human population. In this review we attempt to summarize the experimental as well as the epidemiological basis for the possible role of tea and its polyphenols for chemoprevention and chemotherapy of CaP.     

Tea and bone health: Findings from human studies,potential mechanisms,and identification of knowledge gaps

The population of the developed world is aging. With this aging population, strategies for prevention rather than treatment of chronic disease, such as osteoporosis, are essential for preserving quality of life and reducing health care costs. Tea is the second most consumed beverage in the world and is a rich source of flavonoids that may benefit bone health. There is strong evidence from human studies that habitual tea consumption is positively associated with higher BMD at multiple skeletal sites, while the association with fracture risk is less clear. Fracture studies demonstrate a reduction or no difference in fragility fracture with tea consumption. There are key questions that need to be answered in future studies to clarify if higher consumption of tea not only supports a healthy BMD, but also reduces the risk of fragility fracture. And if the latter relationship is shown to exist, studies to elucidate mechanisms can be designed and executed. This review discusses findings from epidemiological studies as well as potential mechanisms by which flavonoids in tea may mediate an effect, and identifies key knowledge gaps in this research area.     

Isolation of Green Tea Catechins and Their Utilization in the Food Industry

Tea is a rich source of catechins, which are well-known antioxidants. Tea consumption has been found to promote human health; however, only drinking tea may not provide a sufficient level of catechins to achieve health benefits. Thus, the utilization of catechins in foods is an alternative way to supplement catechin consumption. Furthermore, catechins can prevent lipid oxidation and improve color and flavour of foods; hence, addition of catechins can also prolong the shelflife of foods. Therefore, catechins have recently been isolated from green tea for utilization in food products to enhance their shelflife and health benefits. This article outlines several methods for the isolation of catechins from green tea, discusses the challenges involved, and reviews the utilisation of catechins in the food industry.     

国内外红茶菌研究进展

红茶菌是用含糖茶水通过接种醋酸菌和酵母,进行发酵生产的一种广受欢迎的健康饮料。近年来,国内外对红茶菌的研究主要集中在其制作工艺优化方面,小部分研究着重在红茶菌发酵动力学模型、抗氧化与抑菌活性的分子作用机理等方面,同时,国外还对红茶菌中的功能因子——葡萄糖二酸-1,4-内酯(D-Saccharic acid 1,4-lactone,DSL)对肝脏等器官的保护作用进行了研究;并且对红茶菌的一种副产物——细菌纤维也进行了深入研究,特别是在细菌纤维的纳米化等方面。本文主要从红茶菌的菌种组成、相关工艺进展和益生功效方面进行阐述,对比国内外红茶菌的研究进展,同时提出一些个人的见解。     

茶多酚对高脂饮食诱导的非酒精性脂肪性肝病预防作用的研究进展

随着饮食习惯的改变和生活水平的提高，特别是高脂饮食的大量摄入，非酒精性脂肪性肝病（non-alcoholic fatty liver disease，NAFLD）发病率正在逐渐升高，西方发达国家平均发病率为20%～30%，我国平均发病率为15%～30%。NAFLD已经成为全球主要的公共卫生问题之一，严重威胁着人类的健康，其临床治疗仍然是一个挑战。茶多酚是从茶叶中提取出来的一种活性物质，其对人体健康有一定益处，特别是在一些常见疾病的预防作用方面具有较大潜力。为进一步系统了解茶多酚对NAFLD的作用，本文对茶多酚预防高脂饮食诱导的NAFLD的研究进展进行总结。     

Tea, coffee and prostate cancer

Worldwide, prostate cancer has the second highest incidence of all cancers in males with incidence and mortality being much higher in affluent developed countries. Risk and progression of the disease may be linked to both genetic and environmental factors, especially dietary factors. Tea and coffee are two of the most popular beverages in the world and have been investigated for possible effects on health outcomes, including cancer. However, very little dietary advice for their consumption exists. The evidence for a relationship between coffee or tea consumption and prostate cancer is reviewed in this paper. While current evidence indicates that coffee is a safe beverage, its consumption probably has no relationship with prostate cancer. Tea, especially green tea, has shown some potential in the prevention of prostate cancer. While evidence from epidemiologic studies is currently inconclusive, strong evidence has emerged from animal and in vitro studies. We also consider what level of evidence is required to make recommendations for preventive measures to the public. Although evidence on the relationship between coffee, tea and prostate cancer is not complete, we consider it strong enough to recommend tea as a healthier alternative to coffee.     

茶叶中产毒真菌污染现状及其生物防控研究进展

茶是世界上三大饮品之一, 其饮用安全性对于消费者健康以及茶产业发展尤为重要。产毒真菌在自然界中分布广泛, 茶叶在生长、采摘、加工、运输以及仓储过程中存在潜在的真菌污染。真菌毒素是真菌代谢产生的一类有毒次级代谢产物, 会在茶叶基质中积累, 不仅给人类健康造成严重威胁, 也给全球经济带来巨大损失。我国是茶叶生产和出口大国, 随着国际贸易壁垒的日益森严, 进口国对茶叶中残留的微生物和真菌毒素检测愈加严格。此外, 检测茶叶中真菌及真菌毒素对于茶叶安全、茶叶仓储及相关行业标准具有一定的指导意义。本文综述了国内外红茶、黑茶、绿茶、白茶、青茶和黄茶中产毒真菌污染现状及生物防控的研究进展, 并就今后防范措施提出建议, 以期为茶叶中真菌及其真菌毒素安全控制提供参考, 促进茶产业健康可持续发展。     

茶多酚调节肠道菌群及抗肥胖作用研究进展

茶是世界上最受欢迎的饮料之一,其含有丰富的茶多酚,近来,茶多酚对肠道菌群的调节作用引起了学术界的关注。肥胖可以导致心血管疾病、糖尿病、癌症等慢性疾病,因此抗肥胖物质的研究与开发也是当下的研究热点之一,茶多酚的抗肥胖作用也是其中的重要领域。本综述总结了茶多酚、肠道菌群以及肥胖三者的作用关系,并对近5年相关的非临床以及临床研究进行了总结分析。总结发现茶多酚可以调节肠道菌群组成,而肠道菌群也可以影响茶多酚的吸收与代谢。茶多酚可以通过增加益生菌的丰度以及调节能量消耗、营养物质消化吸收、脂质分解代谢和抑制脂肪细胞合成等方式发挥抗肥胖作用。目前对于茶多酚调节肠道菌群和抗肥胖作用的研究以动物模型为主,且大多实验结果证实了茶多酚的肠道菌群调节作用及抗肥胖作用,但是作用剂量尚不明确,且茶多酚剂量毒性研究不足。另外该领域临床研究不足,需要在未来进行更大样本量和更长时间的研究,以实现茶渣等副产物的高价值利用并减少肥胖相关疾病。     

茶叶农药残留与检测技术

我国是茶叶生产大国,每年种植面积大,产量位居世界首位。由于长期以来茶树病虫的发生,出现了很多不合理用药现象。大部分的茶树病虫治理只是单纯的针对一种或者多种茶树病虫害的防治,无法达到大规模的病虫治理。在防治的方法上,侧重化学治理忽视了生物之间的关系,导致茶树农药残留含量超标,茶叶质量不过关等。随着茶叶大量销售全国乃至出口,我国茶叶农药残留问题变得日益突出。本文简述了我国茶叶目前的农残情况,综述茶叶中农药残留的一些常用的检测技术以及减少茶叶农残的方法,并对其发展方向进行了展望,以期为今后开展茶叶中农药残留的分析研究提供参考。     

茶叶质量安全主要化学影响因素分析方法研究进展

茶叶是一种很受欢迎的饮料作物,具有独特的香气、药用及保健功效,深受消费者喜爱。现代工业的迅速 发展和化肥、农药的大量使用造成了严重的环境污染、生态破坏等问题,导致茶叶质量安全受到严重威胁,引起社 会的广泛关注。本文总结相关文献,从茶叶样品的前处理技术和检测技术两个方面,对影响茶叶质量安全的主要化 学因素农药残留、重金属残留和真菌毒素的分析方法进行了总结,对各方法的优缺点进行了比较,并对未来的发展 趋势进行了展望,以期为今后开展相关的检测研究提供参考。     

茶多酚提取与纯化方法及其功能活性研究进展

茶是世界上三大无酒精饮料之一,已有上千年的饮用历史。茶叶中富含茶多酚,具有良好的食用价值和药用价值,开发前景广阔。本文简要介绍了茶多酚的组成结构及性质,并综述了茶多酚的提取与纯化方法及特点,以及茶多酚在抗氧化、抗肿瘤、抗辐射、抗动脉粥样硬化等方面的研究进展,最后对茶多酚的研究前景进行展望,以期为茶多酚的研究和应用提供一定的理论参考。     

饮茶和食管癌关系的研究进展

茶是除水以外消耗最多的一种饮料,在日常生活中随处可见。茶多酚是茶叶中主要的活性成分之一,研究表明,茶多酚具有抗氧化、抗肿瘤等作用,可作为癌症的保护因素。而喜食烫食可能会损伤食管黏膜,使食道上皮细胞脱落、更新加快,从而增加食管癌的发病风险。关于饮茶与食管癌关系的研究至今还没有得到一致的结论。本文主要从茶的消耗量、茶的种类、饮茶温度3 方面对近年来茶和食管癌关系的研究进行综述,并对未来的研究重点进行展望。     

Tea and Its Consumption: Benefits and Risks

The recent convention of introducing phytochemicals to support the immune system or combat diseases is a centuries’ old tradition. Nutritional support is an emerging advancement in the domain of diet-based therapies; tea and its constituents are one of the significant components of these strategies to maintain the health and reduce the risk of various malignancies. Tea is the most frequently consumed beverage worldwide, besides water. All the three most popular types of tea, green (unfermented), black (fully fermented), and oolong (semifermented), are manufactured from the leaves of the plant Camellia sinensis. Tea possesses significant antioxidative, anti-inflammatory, antimicrobial, anticarcinogenic, antihypertensive, neuroprotective, cholesterol-lowering, and thermogenic properties. Several research investigations, epidemiological studies, and meta-analyses suggest that tea and its bioactive polyphenolic constituents have numerous beneficial effects on health, including the prevention of many diseases, such as cancer, diabetes, arthritis, cardiovascular disease (CVD), stroke, genital warts, and obesity. Controversies regarding beneficialts and risks of tea consumption still exist but the limitless health-promoting benefits of tea outclass its few reported toxic effects. However, with significant rise in the scientific investigation of role of tea in human life, this review is intended to highlight the beneficial effects and risks associated with tea consumption.     

Tea consumption and disease correlations

Tea is the most widely consumed beverage in the world next to water and is obtained from the leaves Camellia sinensis. In recent years, the potential health benefits and effect mechanisms of tea have attracted a lot of interest. The potential health benefits of tea have been attributed to its various phenolic compounds with unique biological properties found in tea. These phenolic compounds are especially catechins and their derivatives, which constitute at most 30% of the dry weight of the tea. Tea is a new and effective strategy for reducing the severity of neurological diseases and for protecting against obesity, cardiovascular disease, type 2 diabetes and certain types of cancer (ovaryum, lung, skin, breast, endometrial, prostate, bladder, oral and colorectal cancers).Overall, the study that supports the health benefits of tea is increasing. But, the amounts of and the frequency of tea consumption that is associated with potential health benefits vary greatly from work to work and this situation creates difficulty in determining the optimal consumption amount and frequency that tea can exhibit health benefits. For this reason, we aimed to examine the health effect of the tea and how much consumption is to investigate whether it meets the claimed health benefits.Within that frame, there is a need for more studies on the possible health effects of tea. While studying on that effect, the effects of various doses, forms (in synthetic or natural product matrix), exposure in different periods (short or long term) on health should be studied. However, currently the conducted studies are promising for tea is a bioactive component like polyphenol, theaflavins, thearubigins, caffeine and mineral. In addition, although the fact intake with diet proved to be reliable at the end of the conducted acute and chronic toxicity test is another positive part, safety of bioactive component in tea should be supported through further studies.     

Medicinal and therapeutic potentialities of tea (Camellia sinensis L.) – A review

The medicinal effects of tea have a history dating back almost 5000 years. The chemical components of green tea chiefly include polyphenols, caffeine and amino acids. Tea also contains flavonoids, compounds reported to have anti-oxidant properties having many beneficial effects. Tea flavonoids reduce inflammation, have antimicrobial effects and prevent tooth decay. Consumption of tea may have diuretic effects due to the caffeine. A related compound found in tea is theophylline, a licensed medicine for the treatment of respiratory diseases such as asthma. Today’s computer-driven world can generate complicated lifestyle-related disorders and consumption of certain natural product like tea may very well replace the ill-effects of chemical drugs leading to a safer world with happier life. The paper is an overview of revealing all such ethno medicinal research efforts throughout the world over the times.     

Chemoprevention of lung cancer by tea

Tea is the second only to water as the most consumed beverage in the world. Both green and black teas have been studied for their health benefits for a variety of diseases, particularly cancer. Lung cancer is the predominant cause of cancer mortality in developed countries. Smokers' risk of lung cancer is 20 times that of persons who have never smoked. Epidemiological studies on the cancer-preventive effects of tea produce inconsistent results, which could in part be attributed to the lack of a universal standard for tea preparations. However, most animal studies indicate that tea has strong chemopreventive effects against lung tumorigenesis. The reported mechanisms for chemopreventive activity of green tea are antioxidation, induction of phase II enzymes, inhibition of TNFalpha expression and release, inhibition of cell proliferation, and induction of apoptosis. Cell cycle arrest and apoptosis induced by green tea are probably the two most significant factors. Future studies are needed to determine how green tea affects the genes associated with cell cycle regulation and apoptosis during the mouse lung carcinogenesis process.     

A Review on Kombucha Tea—Microbiology,Composition, Fermentation,Beneficial Effects,Toxicity, and Tea Fungus

Fermentation of sugared tea with a symbiotic culture of acetic acid bacteria and yeast (tea fungus) yields kombucha tea which is consumed worldwide for its refreshing and beneficial properties on human health. Important progress has been made in the past decade concerning research findings on kombucha tea and reports claiming that drinking kombucha can prevent various types of cancer and cardiovascular diseases, promote liver functions, and stimulate the immune system. Considering the widespread reports on kombucha, we recognized the need to review and update the research conducted in relation to kombucha tea, its products and tea fungus. Existing reports have suggested that the protective effects of kombucha tea are as good as those of black tea, however, more studies on kombucha tea and its composition are needed before final conclusions can be made.     

Tea, hormone-related cancers and endogenous hormone levels

Tea is one of the most popular beverages consumed around the world, second only to water. There has been substantial interest in the potential role of tea in cancer prevention, particularly in respiratory and gastrointestinal tract cancers. Recent epidemiological data have linked tea intake to reduced risk of hormone-related cancers, including breast, ovarian and prostate cancers. Based on sparse data, there is suggestion that tea intake may influence circulating hormone levels, providing a plausible mechanism whereby tea intake may influence risk of hormone-related cancers. The major objectives of this paper are to review the epidemiological evidence on tea and risk of breast, ovarian, and prostate cancers as well as the human and non-human studies on tea and circulating hormone levels. We pay special attention to some of the limitations of the human studies and discuss future research needs.     

茶叶儿茶素保健及药理功能研究新进展

人类饮茶已有数千年的历史,饮茶有利于人体健康已被大量科学研究所证实,儿茶素是茶叶诸多保健及药理功能之首要成分,本文将儿茶素诸多的保健及药理功能总结为"三抗(抗癌、抗衰、抗氧化)"、"三降(降血糖、降血脂、降血压)"及"三消(消毒、消炎、消臭)"等十大功效并对其进行了系统综述。