Research Database

The only comprehensive database for clinical and medical research papers on the healthy benefits of matcha/green tea

Recent Research Papers on
heart-health

Green tea and bone metabolism

Author: Chwan-Li Shen and James K. Yeh and Jay J. Cao and Jia-Sheng Wang

Osteoporosis is a major health problem in both elderly women and men. Epidemiological evidence has shown an association between tea consumption and the prevention of age-related bone loss in elderly women and men. Ingestion of green tea and green tea bioactive compounds may be beneficial in mitigating bone loss of this population and decreasing their risk of osteoporotic fractures. This review describes the effect of green tea or its bioactive components on bone health, with an emphasis on (i) the prevalence and etiology of osteoporosis; (ii) the role of oxidative stress and antioxidants in osteoporosis; (iii) green tea composition and bioavailability; (iv) the effects of green tea and its active components on osteogenesis, osteoblastogenesis, and osteoclastogenesis from human epidemiological, animal, as well as cell culture studies; (v) possible mechanisms explaining the osteoprotective effects of green tea bioactive compounds; (vi) other bioactive components in tea that benefit bone health; and (vii) a summary and future direction of green tea and bone health research and the translational aspects. In general, tea and its bioactive components might decrease the risk of fracture by improving bone mineral density and supporting osteoblastic activities while suppressing osteoclastic activities.

 

 

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The potential role of green tea catechins in the prevention of the metabolic syndrome – A review

Author: Frank Thielecke and Michael Boschmann

The metabolic syndrome (MetS) represents an emerging health burden for governments and health care providers. Particularly relevant for prevention and early management of MetS are lifestyle conditions including physical activity and the diet. It has been shown that green tea, when consumed on a daily basis, supports health. Many of the beneficial effects of green tea are related to its catechin, particularly (−)-epigallocatechin-3-gallate (EGCG), content. There is conclusive evidence from in vitro and animal studies which provide the concepts for underlying functional mechanisms of green tea catechins and their biological actions. An increasing number of human studies have explored the effects of green tea catechins on the major MetS conditions such as obesity, type-2 diabetes and cardiovascular risk factors. This article provides a comprehensive overview of the human studies addressing the potential benefits of green tea catechins on the MetS. The number of human studies in this field is still limited. However, the majority of human epidemiological and intervention studies demonstrate beneficial effects of green tea or green tea extracts, rich in EGCG on weight management, glucose control and cardiovascular risk factors. The optimal dose has not yet been established. The current body of evidence in humans warrants further attention. In particular, well-controlled long-term human studies would help to fully understand the protective effects of green tea catechins on parameters related to the MetS.

 

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Comparison of anti-glycation capacities of several herbal infusions with that of green tea

Author: Su-Chen Ho and Szu-Pei Wu and Shyh-Mirn Lin and Ya-Li Tang

Advanced glycation end-products (AGEs) are implicated in the pathogenesis of diabetic microvascular complications and microvascular complications of the aged. Dietary compounds that can reduce glycation may reasonably serve as valuable adjuvants, promoting the health of the aged and diabetics. This work evaluates and compares the anti-glycation activities of different herbal infusions with that of green tea, a well-documented anti-glycation beverage. The anti-glycation activity of herbal infusions were determined based on the ability of an infusion to attenuate the formation of fluorescent AGEs in glucose- and methylglyoxal-mediated protein glycation systems. All of the tested herbs except for lemongrass and rosemary—balm, mint, black tea, sage and common verbena—had potent anti-glycation abilities that exceeded or equalled that of green tea. Additionally, the amounts of phenolics and flavonoid in the herbal infusions were highly correlated with their anti-glycation activity, revealing that the anti-glycation activity of herbal infusions was primarily attributable to phenolics, particularly flavonoids.

 

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Dietary green tea extract increases phase 2 enzyme activities in protecting against myocardial ischemia-reperfusion

Author: Masoumeh Akhlaghi and Brian Bandy

Green tea catechins are dietary antioxidant compounds that have been shown to protect against myocardial ischemia-reperfusion (IR) injury. Considering reports that catechins can induce phase 2 enzymes in cultured cells and some organs, we hypothesized that part of the protection to heart against IR injury may involve elevation of phase 2 enzyme activities. Rats were fed for 10 days with either control diet (sham and control groups) or the diet mixed with 0.25% green tea extract. At the end of 10 days, hearts were excised and subjected to global ischemia for 20 min followed by reperfusion for 2 hours. The hearts were compared for indices of cell death, oxidative stress, and phase 2 enzyme activities. Hearts from the green tea group had a 65% to 85% decrease in markers of apoptosis, a tendency to higher total glutathione, and higher activities of the phase 2 enzymes glutamate cysteine ligase and quinone reductase. The results support a possible involvement of phase 2 enzymes in the protection by green tea catechins against myocardial IR injury.

 

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In vitro inhibition of α-glucosidases and glycogen phosphorylase by catechin gallates in green tea

Author: Ogusa Kamiyama and Fujiko Sanae and Kyoko Ikeda and Yasuhiko Higashi and Yasuhiro Minami and Naoki Asano and Isao Adachi and Atsushi Kato

We investigated in vitro inhibition of mammalian carbohydrate-degrading enzymes by green tea extract and the component catechins, and further evaluated their inhibitory activities in cell cultures. The extract showed good inhibition toward rat intestinal maltase and rabbit glycogen phosphorylase (GP) b, with IC50 values of 45 and 7.4 μg/ml, respectively. The polyphenol components, catechin 3-gallate (CG), gallocatechin 3-gallate (GCG), epicatechin 3-gallate (ECG), and epigallocatechin 3-gallate (EGCG), were good inhibitors of maltase, with IC50 values of 62, 67, 40, and 16 μM, respectively, and EGCG also showed good inhibition toward maltase expressed on Caco-2 cells, with an IC50 value of 27 μM. The ungallated catechins, such as catechin, gallocatechin (GC), epicatechin (EC), and epigallocatechin (EGC), showed no significant inhibition toward GP b, whereas the gallated catechins CG, GCG, ECG, and EGCG inhibited the enzyme, with IC50 values of 35, 6.3, 27, and 34 μM. From multiple inhibition studies by Dixon plots, GCG appears to bind a new allostelic site, the indole inhibitor site. These gallated catechins also inhibited glucagon-stimulated glucose production dose-dependently, with IC50 values ranging from 33 to 55 μM. Dietary supplementation with these gallated catechins or the green tea extract containing them, which inhibits both α-glucosidases and GP in vitro and in cell culture, would contribute to the protection or improvement of type 2 diabetes.

 

 

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Green tea catechins, caffeine and body-weight regulation

Author: M.S. Westerterp-Plantenga

The global prevalence of obesity has increased considerably in the last decade. Tools for obesity management including caffeine, and green tea have been proposed as strategies for weight loss and weight maintenance. These ingredients may increase energy expenditure and have been proposed to counteract the decrease in metabolic rate that is present during weight loss. Positive effects on body-weight management have been shown using green tea mixtures. Green tea, by containing both tea catechins and caffeine, may act through inhibition of catechol O-methyl-transferase, and inhibition of phosphodiesterase. Here the mechanisms may also operate synergistically. A green tea–caffeine mixture improves weight maintenance, through thermogenesis, fat oxidation, and sparing fat free mass. The sympathetic nervous system is involved in the regulation of lipolysis, and the sympathetic innervation of white adipose tissue may play an important role in the regulation of total body fat in general. Taken together, these functional ingredients have the potential to produce significant effects on metabolic targets such as thermogenesis, and fat oxidation. An ethnic or genetic effect, and habitual caffeine or green tea catechin intake may act as confounders; this remains to be revealed.

 

 

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Tea flavonoids and cardiovascular health

Author: Jonathan M. Hodgson and Kevin D. Croft

The two main types of tea are green and black. Both green and black teas are rich dietary sources of flavonoids. Available evidence suggests that regular tea consumption may reduce the risk of cardiovascular disease. The cardiovascular health benefits of drinking tea are thought to be largely due to flavonoids. Tea intake and intake of flavonoids found in tea have been associated with reduced risk of cardiovascular disease in cross-sectional and prospective population studies. Isolated flavonoids found in tea have also been consistently shown to inhibit the development of atherosclerosis in animal models. A number of possible pathways and mechanisms have been investigated. There is now consistent data indicating that tea and tea flavonoids can enhance nitric oxide status and improve endothelial function, which may be at least partly responsible for benefits on cardiovascular health. There is also evidence, although limited, to suggest benefits of green tea (flavonoids) on body weight and body fatness. Data supporting reduced oxidative damage, inflammation, platelet activation, blood pressure, and risk of type 2 diabetes with tea (flavonoids) remains inadequate to draw any conclusions.

 

 

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Anti-apoptotic action of polyphenols derived from red wine and green tea against beta-amyloid in hippocampal cells

Author: Stéphane Bastianetto and Slavica Krantic and Rémi Quirion

Background: It has been suggested that accumulation of amyloid-beta (Aß) peptides into senile plaques plays a pivotal role in neuronal cell death occuring in Alzheimer's disease (AD). Aß produces two major types of programmed cell death (PCD) in vitro which requires the activation of effectors of caspase-dependent and -independent cell death pathways, namely caspase-3 and apoptosis inducing factor (AIF). Published data comparing the expression of AIF in post-mortem brains from AD patients and neurologically normal subjects in the course of aging suggest the relevance of AIF in the pathogenesis of AD Reix et al, Neurobiol Aging 28:351, 2007; Yu et al., Am. J. Path., in press). Recent epidemiological studies have reported that elderly people have a lower risk (up to 50%) to develop AD if they regularly eat fruits and vegetables and drink a moderate amount of tea and red wine. Numerous studies indicate that polyphenols derived from these foods and beverages account for the observed neuroprotective effects. In particular, polyphenols extracted from green tea (i.e. epigallocatechin gallate or EGCG) or red wine (i.e. resveratrol) blocked hippocampal cell death against Aß-induced toxicity (Bastianetto et al, Eur J Neurosci 23:55, 2006; Han et al, Br J Pharmacol 141:997, 2004). Our main objective is to determine whether concurrent inactivation of both main types of PCD may have additive therapeutic benefit in AD. Methods: Mixed hippocampal cell cultures were prepared from E19 fetuses obtained from Sprague-Dawley rats. They were grown in D-MEM high glucose containing 10% (v/v) fetal bovine serum. Experiments were performed in 6-day-old cultures. Results: The 24-hour exposure of cultured hippocampal cells to Aß1-42 (15 μM) alone or in combination with either resveratrol (20 μM) or EGCG (10 μM) reduced Aß1-42-mediated increased expression of the 57 kDa death-inducing form of AIF. Moreover, EGCG completely inhibited the activation of the key apoptotic executioner, caspase-3, and reduce the number of apoptotic cells, whereas resveratrol was less effective. Conclusions: Our findings show that these polyphenols do not share the same mechanism of action, suggesting that a combination of EGCG and resveratrol might provide additional neuroprotection against Aß-associated cell death.

 

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New Insights into Anticancer Effect of Green Tea Polyphenol Epigallocatechin-3-gallate in Hypoxia by Metabolic Profiling

Author: Yoshinori Fujimura and Shuntaro Tsukamoto and Miho Irie and Daisuke Miura and Hiroyuki Miura and Hirofumi Tachibana

 

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Green tea averts age-dependent decline of hippocampal signaling systems related to antioxidant defenses and survival

Author: Marco Assunção and Maria J. Santos-Marques and Félix Carvalho and José P. Andrade

We previously found that prolonged consumption of green tea (GT), a rich source of antioxidant polyphenols, protected proteins and lipids against oxidation and reduced lipofuscin deposition in the rat hippocampal formation as well as improving spatial memory during aging. In this work, we sought to investigate whether GT treatment could interfere with age-related changes in redox status and cellular signaling systems related to oxidative stress and survival in the same brain region. To address this issue, five male Wistar rats were fed with GT from 12 to 19 months of age and results were compared to those obtained from controls age 19 months (C-19 M). A third group of rats was evaluated at 12 months of age to provide baseline data. At completion of the specified time points, the glutathione levels and antioxidant enzyme activities, the activation of the transcription factors cyclic AMP response element-binding (CREB) and nuclear factor-κB (NF-κB, p50 and p65 subunits), and the levels of brain-derived neurotrophic factor (BDNF) and B-cell lymphoma-2 (Bcl-2) were measured in hippocampal formations. GT-treated rats presented higher reduced and lower oxidized glutathione levels and displayed favorable alterations in antioxidant enzyme activities compared to C-19 M animals. In addition, GT increased CREB activation and the levels of BDNF and Bcl-2, but had no effect on activation of NF-κB subunits, relative to age-matched controls. We conclude that long-term GT ingestion improves antioxidant systems and activates CREB in the aging rat hippocampal formation, leading to neuroprotection mediated by downstream upregulation of BDNF and Bcl-2.

 

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Other Popular Research Topics

Cognitive Function

Cognitive Function

Matcha consumption leads to much higher intake of green tea phytochemicals compared to regular green tea. Previous research on caffeine, L-theanine, and epigallocatechin gallate (EGCG) repeatedly demonstrated benefits on cognitive performance.

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Mental Health

Mental Health

Matcha contains an amino acid called L-theanine, which has been shown to reduce physiological and psychological stresses. L-theanine also improves cognition and mood in a synergistic manner with caffeine, and promotes alpha wave production in the brain

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Cancer Prevention

Cancer Prevention

Matcha/green tea has for many centuries been regarded as an essential part of good health in Japan and China. Many believe it can help reduce the risk of cancer, and a growing body of evidence backs this up.

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Immunity

Immunity

A recent study in the journal Proceedings of the National Academy of Sciences concluded that drinking matcha daily greatly enhanced the overall response of the immune system. The exceedingly high levels of antioxidants in matcha mainly take the form of polyphenols, catechins, and flavonoids, each of which aids the body’s defense in its daily struggles against free radicals that come from the pollution in your air, water and foods.

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