All teas are not created equal: The Chinese green tea and cardiovascular health

doi:10.1016/j.ijcard.2005.05.038

International Journal of Cardiology

Volume 108, Issue 3, 14 April 2006, Pages 301-308

https://doi.org/10.1016/j.ijcard.2005.05.038 Get rights and content

Abstract

Tea is one of the most widely consumed beverages in the world, next only to water. It can be categorized into three types, depending on the level of fermentation, i.e., green (unfermented), oolong (partially fermented) and black (fermented) tea. In general, green tea has been found to be superior to black tea in terms of antioxidant activity owing to the higher content of (−)-epigallocatechin gallate. The processes used in the manufacture of black tea are known to decrease levels of the monometric catechins to a much greater extent than the less severe conditions applied to other teas. The cardioprotective effect of flavonoids from green tea can be attributed to not only antioxidant, antithrombogenic and anti-inflammatory properties but also improvement of coronary flow velocity reserve. In this article, I will discuss the effects of green tea on atherosclerosis, coronary heart disease, hypertension, diabetes, metabolic syndrome and obesity, and, finally, its comparison with black tea.

Introduction

Tea is one of the most widely consumed beverages in the world, next only to water [1], [2] and well ahead of coffee, beer, wine and carbonated soft drinks [3]. It can be categorized into three types, depending on the level of fermentation, i.e., green (unfermented), oolong (partially fermented) and black (fermented) tea. Although this process is often assumed, incorrectly, to be fermentation which usually implies additives, the more correct term should be oxidation which means exposure to air while drying [4]. In general, green tea has been found to be superior to black tea in terms of antioxidant activity owing to the higher content of (−)-epigallocatechin gallate [5], [6], [7]. The processes used in the manufacture of black tea are known to decrease levels of the monometric catechins to a much greater extent than the less severe conditions applied to other teas [5], [6]. The production and consumption of the partially fermented oolong tea are confined to China [1].

The cardioprotective effect of flavonoids from green tea can be attributed to not only antioxidant [5], antithrombogenic [8], [9] and anti-inflammatory [10] properties but also improvement of coronary flow velocity reserve [1], [11]. In this article, I will discuss the effects of green tea on atherosclerosis, coronary heart disease, hypertension, diabetes, metabolic syndrome and obesity, and, finally, its comparison with black tea.

Section snippets

Antioxidant effect

The protective effect of tea (Camellia sinensis) against atherosclerosis has been attributed to the antioxidant activity of the flavonoids [3], [5], [12]. Over 4000 different flavonoids have been described, and they are categorized into flavonols, flavones, catechins, flavanones, anthocyanidins and isoflavonoids [13]. Green tea has been shown to retard atherosclerosis in both experimental animals [14], [15], [16], [17], [18], [19] and humans [20], [21]. However, although the results in animals

Hypertension

In ancient Chinese medicine, tea has long been believed to possess hypotensive effects [50]. However, conflicting results have been shown among human trials as well as animal studies on the relation between tea consumption and blood pressure. The controversy, which is partly due to the fact that tea contains caffeine that can transiently increase blood pressure, has largely been resolved by the recent studies of Hodgson and Puddey [51]. They found that in population studies people generally

Diabetes

Atherosclerosis accounts for some 80 % of all diabetic mortality; about three-quarters of the cardiovascular deaths from diabetes result from coronary artery disease [58]. Plants containing flavonoids have been used to treat diabetes in Indian medicine [59]. The green tea flavonoid has been shown to have insulin-like activities [59] as well as insulin-enhancing activity [60]. However, epigallocatechin gallate, which is the principal catechin in green tea, differs from insulin in that it affects

Metabolic syndrome

The metabolic syndrome, formerly called metabolic ‘syndrome X’ [67], has reached an epidemic proportion [68] since its original description in 1988 [69]. A cluster of abnormalities defines the metabolic syndrome, including insulin resistance, hypertension, obesity, hypertriglyceridemia, low HDL cholesterol and inflammation [70].

Green tea has been shown recently to be a promising tool against the metabolic syndrome in China [66]. According to Campbell [66], Chinese researchers have experimented

Obesity

Obesity has increased at an alarming rate in recent years and is now a worldwide health problem [71], including China [71], [72]. It has been known for some time that tea helps to control obesity, and this is common knowledge in China. A Chinese classical pharmaceutical book called the Bencao Shiyi (The Conpendium of Materia Medica) states: “Drinking tea for a long time will make one live long to stay in good shape without becoming too fat and too heavy” [73].

The mechanisms of action of tea in

Green tea vs. black tea

While there are hundred varieties of teas, most can be categorized into 3 types, depending on the level of fermentation or oxidation, i.e., green (unfermented), oolong (partially fermented) and black (fermented) tea. Green teas are not fermented during processing and thus retain the original color of the tea leaves; the most famous green tea is the Lung Chen Tea (Dragon Well Tea), grown in the hillside of Hangzhou, Zhejiang Province, China. Black teas are made from fermented leaves which

Conclusion

According to Chinese legends, tea was discovered by the Emperor Shen Nong in about 2700 BC, when a gust of wind blew tea leaves into a kettle of boiling water [92]. Emperor Shen Nong reputedly said in 2737 BC that tea can provide “vigor of body, contentment of mind, and determination of purpose” [106]. Since then green tea has been a staple product and the main beverage in China [12], [92]. It is the Chinese national drink served at all meals of the day to everyone from the president to the

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Thus, we were compelled to compile available evidence amid the surge of Omicron infection, with the hope that EGCG will receive the attention it deserves in the battle against Omicron. Green tea, made from the leaves of the Camellia sinensis L. species of the Theaceae family via non-fermented processing, has been used as a crude medicine for over 4000 years in China (Cheng, 2004, 2006; Han et al., 2016). Now it is a popular beverage worldwide, especially in adults starting to focus on health concerns, because it does not have significant caloric content and yet possibly possesses multiple health-promoting effects, such as body weight control, metabolic syndrome alleviation, prevention of cancer, diabetes mellitus, and cardiovascular, neurodegenerative or infective diseases (Yang et al., 2002; Yang et al., 2016; Zhang et al., 2019; Z. Zhang et al., 2021; Zhao et al., 2020).
COVID-19 due to SARS-CoV-2 infection has had an enormous adverse impact on global public health. As the COVID-19 pandemic evolves, the WHO declared several variants of concern (VOCs), including Alpha, Beta, Gamma, Delta, and Omicron. Compared with earlier variants, Omicron, now a dominant lineage, exhibits characteristics of enhanced transmissibility, tropism shift toward the upper respiratory tract, and attenuated disease severity. The robust transmission of Omicron despite attenuated disease severity still poses a great challenge for pandemic control. Under this circumstance, its tropism shift may be utilized for discovering effective preventive approaches.
This review aims to estimate the potential of green tea epigallocatechin gallate (EGCG), the most potent antiviral catechin, in neutralizing SARS-CoV-2 Omicron variant, based on current knowledge concerning EGCG distribution in tissues and Omicron tropism.
EGCG has a low bioavailability. Plasma EGCG levels are in the range of submicromolar concentrations following green tea drinking, or reach at most low μM concentrations after pharmacological intervention. Nonetheless, its levels in the upper respiratory tract could reach concentrations as high as tens or even hundreds of μM following green tea consumption or pharmacological intervention. An approach for delivering sufficiently high concentrations of EGCG in the pharynx has been developed. Convincing data have demonstrated that EGCG at tens to hundreds of μM can dramatically neutralize SARS-CoV-2 and effectively eliminate SARS-CoV-2-induced cytopathic effects and plaque formation. Thus, EGCG, which exhibits hyperaccumulation in the upper respiratory tract, deserves closer investigation as an antiviral in the current global battle against COVID-19, given Omicron's greater tropism toward the upper respiratory tract.
Chemical components in yellow mealworm (Tenebrio molitor L.) reared with tea powder
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The yellow mealworms (Tenebrio molitor L.) were reared by different ratios of tea powder and wheat bran powder mixtures, and weighted every day during the whole 10 days rearing. The content of tea polyphenols, total catechins, catechin (C), epicatechins (EC), epigallocatechins (EGC), epicatechin gallates (ECG), epigallocatechin gallates (EGCG), and nutrition components such as protein and fatty acid in the yellow mealworms were determined after 10 days rearing. The yellow mealworms can put on weight and grow well when the proportion of tea powder belows 80%, while 100% tea powder rearing has no signifi cantly reduced the weight of yellow mealworms. The content of tea polyphenols, total catechins, C, EC, EGC, ECG, and EGCG all enhance signifi cantly along with the increase ratio of the tea powder. The protein content increase more signifi cantly at 50% and 80% ratios treatments than the other treatments. Tea powder added rearing reduces the content of saturated fatty acid, and has a complex effect on the content of unsaturated fatty acid. Comprehensive analysis of the components determined show that 50% ratio is the best for yellow mealworm rearing.
Mycotoxins in raw materials, beverages and supplements of botanicals: A review of occurrence, risk assessment and analytical methodologies
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Tea is generally categorized into three major categories, i.e., black (fully fermented), green (unfermented), and oolong tea (semi-fermented), based on the fermentation process; however, tea includes other different types depending also on the processing or harvested leaf development, including white and yellow tea (slightly fermented), cyan tea (semi-fermented) and Pu-erh tea (post-fermented). Among the different types, black tea represents 78% of total tea consumed, green tea 20% and Oolong tea less than 2% (Cheng, 2006; Feng et al., 2019), thus, black tea is the most commonly consumed tea worldwide and is estimated to be around 78% of total tea produced (Soni et al., 2015). Tea is obtained from the leaves of Camellia sinensis and is commonly consumed by pouring hot water over cured leaves.
Over recent years, consumer interest in natural products, such as botanicals has increased considerably. One of the factors affecting their quality is the presence of mycotoxins. This review focuses on exploring the mycotoxin occurrence in botanicals (raw material and ready-to-eat forms such as infusions or tablets) and the risk assessment due to their ingestion. Aflatoxins, Ochratoxin A, and Fumonisins are the most commonly studied mycotoxins and data in the literature report levels ranging from traces to 1000 μg/kg in raw materials. In general, the highest contents observed in raw materials decreased to unconcerning levels after the preparation of the infusions, reaching values that generally do not exceed 100 μg/L. Regarding botanical dietary supplements, the levels observed were lower than those reported for other matrices, although higher levels (of up to 1000 μg/kg) have been reported in some cases. Risk assessment studies in botanicals revealed a higher risk when they are consumed as tablets compared to infusions. Analytical methodologies implied in mycotoxin determination have also been contemplated. In this sense, liquid chromatography coupled to fluorescence detection has been the most frequently employed analytical technique, although in recent years tandem mass spectrometry has been widely used.
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ReviewAll teas are not created equal: The Chinese green tea and cardiovascular health

Abstract

Introduction

Section snippets

Antioxidant effect

Hypertension

Diabetes

Metabolic syndrome

Obesity

Green tea vs. black tea

Conclusion

Am J Cardiol

J Nutr

Prev Med

Lancet

Am J Cardiol

Am J Cardiol

Atherosclerosis

J Nutr

J Nutr

Ann Epidemiol

J Nutr

J Am Coll Cardiol

J Biol Chem

Atherosclerosis

Prostaglandins Leukot Essent Fatty Acids

Thromb Res

Am J Cardiol

Kidney Int

Med Hypotheses

J Biol Chem

Diabetes Res Clin Pract

Am J Cardiol

Phytomedicine

Am J Clin Nutr

Prim Care

J Nutr

FEBS Lett

Prev Med

Am J Clin Nutr

Am J Clin Nutr

Black and green tea and heart disease: a review

Biofactors

Tea is good for the heart

Arch Intern Med

Antioxidants in wine and tea

J R Soc Med

Epidemiological evidence on potential health properties of flavonoids

Proc Nutr Soc

Antioxidants in Chinese green tea

J Am Coll Cardiol

Flavonoids: risks or therapeutic opportunities?

Recenti Prog Med

Differential effects of green tea-derived catechin on developing versus established atherosclerosis in apolipoprotein E-null mice

Circulation

Green tea polyphenols inhibit advanced glycation end product-induced rat vascular smooth muscle cell proliferation

Di Yi Junyi Daxue Xuebao

Green tea polyphenols inhibit low-density lipoprotein-induced proliferation of rat vascular smooth muscle cells

Di Yi Junyi Daxue Xuebao

Effects of green tea intake on the development of coronary artery disease

Circ J

Role of endothelial dysfunction in atherosclerosis

Circulation

Green tea reverses endothelial dysfunction in healthy smokers

Heart

Effect of green tea on smokers

Heart

Green tea catechins inhibit neointimal hyperplasia in a rat carotid arterial injury model by TIMP-2 overexpression

Cardiovasc Res

Local delivery of green tea catechins inhibits neointimal formation in the rat carotid artery injury model

Heart Vessels

Chinese green tea lowers cholesterol level through an increase in fecal lipid excretion

Life Sci

Flavonoids for reduction of atherosclerotic risk

Curr Atheroscler Rep

A new function of green tea: prevention of lifestyle-related diseases

Ann N Y Acad Sci

Epigallocatechin, a green tea polyphenol, attenuates myocardial ischemia reperfusion injury in rats

Mol Med

Review
All teas are not created equal: The Chinese green tea and cardiovascular health