Here is an essay on ‘Green Tea’ for class 8, 9, 10, 11 and 12. Find paragraphs, long and short essays on ‘Green Tea’ especially written for school and college students.
Essay on Green Tea
1. Essay on Green Tea (As an Anti-Ageing):
Epigallocatechin gallate (EGCG) is a main active ingredient of green tea. The significant longevity-extending effects of EGCG on Caenorhabditis elegans demonstrated by some studies could be attributed to its in vitro and in vivo free radical-scavenging effects and its up-regulating effects on stress-resistance-related proteins, including (1) superoxide dismutase-3 (SOD-3), (2) heat shock protein-16.2 (HSP-16.2) and (3) HSP-16GFP expression.
The survival- enhancing effects of EGCG on C. elegans under stress are very important for anti- ageing research. Unno et al (2007) found that daily consumption of green tea catechin (GT-catechin) prevented memory regression and DNA oxidative damage in the mice. GT-catechin did not prolong the lifetime of senescence-accelerated mice, but it did delay brain senescence. These findings suggested that continued intake of GT-catechin might promote healthy ageing of the brain in older persons. Unno et al. (2008) found that even when ingestion started at the adult age, GT-catechin is helpful in suppressing brain dysfunction with ageing.
The decline in the activity of glutathione peroxidase (GPx), an essential enzyme for reduction of hydrogen and lipid peroxides was prevented in aged mice that had consumed GT-catechin. The increased level of carbonyl proteins, a marker of oxidative damage in proteins, was also significantly reduced in aged mice that had consumed GT-catechin.
2. Essay on Green Tea (As an Anti-Diabetic Food):
Tannins from the seed powder, decoction of flower buds of mature tea tree have been reported to be helpful. Sabu et al. (2002) found the aqueous extract of green tea polyphenols (GTP) to inhibit lipid peroxidation (LP), scavenge hydroxyl and superoxide radicals in vitro.
The observations of Latha and Pari (2003) showed that the aqueous extract of Cassia auriculata possesses an anti-hyperglycemic effect and suggest that enhanced gluconeogenesis during diabetes is shifted towards normal and that the extract enhances the utilization of glucose through increased glycolysis.
The effect of the extract was more prominent than that of glibenclamide. Cassia auriculata flower extract (CFEt), at doses of 0.15, 0.30 and 0.45 g/kg body weight for 30 days, suppressed the elevated blood glucose and lipid levels in diabetic rats. Apart from significant reduction in fasting blood glucose and glycosylated haemoglobin in both mild and severe diabetic rats, serum lipid levels were reversed towards normal in both the groups of rats. Phytochemical screening of CLEt revealed the presence of alkaloids, flavonoids, saponins, tannins and cardiac glycosides with anti-hyperglyceamic and anti-oxidant properties suggesting the extract’s protective role against diabetic complications.
3. Essay on Green Tea (As an Anti-Hyperlipidemic Foods)
Regular intake of epigallocatechin-3-gallate (EGCG) had no effect on insulin resistance but did result in a modest reduction in diastolic blood pressure. This antihypertensive effect may contribute to some of the cardiovascular benefits associated with habitual green tea consumption. EGCG treatment for 7 or 15 days, significantly lowered mean levels of 3,4-methylenedioxyamphetamine, higher mean levels of enzymatic and non-enzymatic anti-oxidants occurred, compared with those in saline-treated rats and protected against the hepatic abnormalities occurring in Wistar rats fed an atherogenic diet.
Pu-erh tea is a variety of fermented dark tea produced in Yunnan province, China. Fermentation is a tea production style in which the tea leaves undergo microbial fermentation and oxidation after they are dried and rolled. Pu-erh tea extract significantly lowered serum low density lipoprotein-cholesterol and triglyceride levels as compared to the control group, (p < 0.05).
Conversely, levels of high density lipoprotein-cholesterol (HDL-C) were elevated in the groups given daily doses of tea extract. This tea significantly reduced the total body weight and the weight of various adipose pads. Pu-erh tea administration also significantly lowered plasma total cholesterol, triglyceride concentrations and low-density lipoprotein- cholesterol levels in rats with high fat diet (HFD)-induced obesity, but did not affect high-density lipoprotein-cholesterol levels.
Kuo et al (2005) evaluated the four major commercial teas, oolong, black, pu-erh, and green teas, for the growth suppressive and hypo-lipidemic effect. They found the fully fermented pu-erh and black tea leaves and partially fermented oolong tea leaves to be more effective on their growth suppressive and hypo-lipidemic effects as compared to the non-fermented green tea leaves. Pu-erh tea significantly increased lipoprotein lipase, hepatic lipase and hormone-sensitive lipase activities in epididymal fat tissue in rats with HFD-induced obesity significantly enhanced mRNA levels of hormone-sensitive lipase in rats with HFD-induced obesity.
Tea extracts prepared from-green, oolong, black and pu-erh tea were tested for their ability to modulate fatty acid synthase expression in rats fed on a high-fructose diet. Interestingly, consuming tea leaves for 12 weeks almost normalized the serum triacylglycerol concentrations. Again, rats fed with fructose/green tea and fructose/ pu-erh tea showed the greatest reduction in serum triglycerides, cholesterol, insulin and leptin levels.
In contrast, serum cholesterol and insulin concentrations of the fructose/oolong tea-fed rats did not normalize. The relative epididymal adipose tissue weight was lower in all rats supplemented with tea leaves than those fed with fructose alone. Furthermore, supplementation of green, black, and pu-erh tea leaves significantly decreased hepatic fatty acid synthase (FAS) mRNA and protein levels, and increased AMPK phosphorylation, compared with those of rats fed with fructose only.
Thus, Huang and Lin (2012) concluded that the intake of green, black, and pu-erh tea leaves ameliorated the fructose-induced hyper-lipidemia and hyper-leptinemia state in part through the suppression of FAS protein levels and increased AMPK phosphorylation.
4. Essay on Green Tea (As an Anti-Inflammatory Foods)
Recently, considerable attention has been focused on phytochemicals from dietary and medicinal sources that inhibit, reverse, or retard diseases caused by oxidative and inflammatory processes.
Three cups of tea provides about 300 mg of polyphenols. The polyphenols in green tea such as Epigallocatechin-3-gallate (EGCG) exhibit chelating, anti-inflammatory, anti-bacterial, anti-mutagenic, anti-diabetic, and hypo-cholesterolemic properties. Studies have also shown that EGCG protects cells by inhibiting DNA damage and oxidation of LDL. One of the protective properties of EGCG is its ability to scavenge free radicals.
Cysteine conjugates of epigallocatechin 3-gallate (EGCG) retain the growth inhibitory, anti-inflammatory, and pro-oxidant activities of EGCG in vitro and may play a role in disease prevention in vivo. Thereby, Green tea lowers the risk of a wide variety of diseases, including cardiovascular disease and cancer.
Green tea polyphenols also reduce the severity of liver injury in association with lower concentrations of lipid peroxidation and pro-inflammatory nitric oxide- generated mediators. EGCG can also reduce the inflammatory response associated with local tissue injuries such as the hepato-cellular necrosis in acute liver injury induced by carbon tetrachloride.
The protective effect of EGCG is due to its ability to decrease lipid peroxidation, oxidative stress and production of nitric oxide (NO) radicals by inhibiting the expression of iNOS. EGCG also ameliorates the overproduction of pro-inflammatory cytokines and mediators, reduces the activity of NF-kappaB and AP-1 and the subsequent formation of peroxynitrite with NO and reactive oxygen species. Investigations by Bruckner et al. (2012) supported the concept of anti-inflammatory properties of EGCG being generally beneficial in the DSS-model of colitis, an effect that may be mediated by its strong anti-oxidative potential.
Bornhoeft et al (2012) reported that green tea supplementation decreased several cardiovascular risk factors, including body composition, dyslipidemia, and inflammatory status in rats fed an atherogenic diet thus supported the fact that green tea as an effective dietary component for sustaining cardiovascular health.
In addition, green tea polyphenol supplementation mitigated myocardial fibrosis through suppression of a chronic inflammation innate immune response and lowered red blood cell counts, hematocrit, and hemoglobin, but not the lipid profiles. Supplementation of green tea polyphenols significantly attenuated the lipo-polysaccharide induced fibrosis in coronary vessels.
Consumption of green tea polyphenols ameliorated the detrimental effects of high-fructose diet on insulin signaling, lipid metabolism and inflammation in the cardiac muscle of rats.
A link between inflammation and cancer has long been suspected. In 2004, Greten et al, found that green tea modulated chronic inflammation that would otherwise contribute to prostate carcinogenesis in vivo. The EGCG-DPA ester (EGCG- molecule esterified with docosapentaenoic acid) exhibited anti-inflammatory potentials.
Specific inactivation of the I kappa B kinase (IKK)/NF- kappa B pathway in two different cell types can attenuate formation of inflammation- associated tumors. In addition to suppressing apoptosis in advanced tumors, IKK beta may link inflammation to cancer. Later, Hsu et al (2010; 2011) found Green tea to decrease prostate inflammatory infiltration, increase Bax/BcL2 ratio and decrease protein expression of tumor necrosis factor-alpha, interleukin (IL)-6 and IL-1β compared to control.
The green tea polyphenol EGCG prevented DON-induced cytotoxicity to HT-29 cells in a dose-response manner. EGCG also protect the body against oxidative stress, up regulation of nuclear factor-kB (NF- κB), cyclooxygenase- 2 (COX-2) and caspase-3 activated apoptosis. The in vivo studies suggested that combination of foods, such as soy and tea, may inhibit hormone- induced pro-inflammatory NFκB signals that contribute to prostate cancer development.
Catechin, epigallocatechin and epigallocatechin-3-gallate decreased the leukocytopenia in mice after irradiation and significantly reduced the elevated serum inflammatory cytokines (TNF-α, IL-1β, and IL-6). The anti-oxidant and anti-inflammatory activities of green tea polyphenol has been attributed to the interaction of the different components through multiple and synergistic mechanisms. Thus, green tea polyphenols have a potential to offer protection against irradiation-induced toxicity.
Nitic oxide (NO) has been implicated in the pathogenesis of various inflammatory diseases, including sunburn and pigmentation induced by ultraviolet irradiation. EGCG inhibited and down regulated the UVB-induced activation and translocation of NF-kappaB, expression of iNOS mRNA and generation of NO respectively, indicating EGCG may play a protective role from UVB-induced skin damage.
El-Mowafy et al. (2011) showed for the first time that EGCG can protect against cisplatin-induced nephro-toxicity at the molecular level, better than resveratrol or quercetin.
Chatterjee et al. (2012) concluded from their comparative study that both green and black tea leaves possessed a marked anti-inflammatory effect against the denaturation of protein, in vitro, with Green tea being more active than black tea, probably due to the higher flavonoid content.
5. Essay on Green Tea (As an Anti-Obesity Foods):
Green tea is the second most popular beverage in the world and has been extensively studied for its putative disease preventive effects. Green tea is characterized by the presence of a high concentration of polyphenolic compounds known as catechins, with (-)-epigallocatechin-3-gallate (EGCG) being the most abundant and most well-studied. During the last decade, the traditional notion that green tea consumption benefits health has received significant scientific attention.
According to Wang and Tian (2001) epigallocatechin gallate from green tea is a strong inhibitor of fatty acid synthase (FAS) both by reversible fast binding and irreversible slow binding. The inhibitory effects were comparable to that of established FAS inhibitors such as cerulenin and C75, a synthetic FAS inhibitor.
Green tea, green tea catechins and epigallocatechin gallate (EGCG) have been demonstrated in cell culture and animal models of obesity to reduce adipocyte differentiation and proliferation, lipogenesis, fat mass, body weight, fat absorption, plasma levels of triglycerides, free fatty acids, cholesterol, glucose, insulin and leptin, as well as to increase beta-oxidation and thermogenesis.
Adipose tissue, liver, intestine, and skeletal muscle are target organs of green tea, mediating its anti-obesity effects. Metabolic syndrome (MetS) is a complex condition that is defined by the presence of elevated waist circumference, dysglycemia, elevated blood pressure, decrease serum high-density lipoprotein- associated cholesterol, and increased serum triglycerides. Studies in both in vitro and laboratory animal models have examined the preventive effects of green tea and EGCG against the symptoms of MetS.
Overall, the results of these studies have been promising and demonstrated that green tea and EGCG have preventive effects in both genetic and dietary models of obesity, insulin resistance, hypertension, and hypercholesterolemia. According to Bose et al. (2008) long-term polyphenol, (-)- epigallocatechin-3-gallate (EGCG) treatment attenuated the development of obesity, symptoms associated with the metabolic syndrome, and fatty liver.
Short-term EGCG treatment appeared to reverse preexisting high-fat-induced metabolic pathologies in obese mice. These effects may be mediated by decreased lipid absorption, decreased inflammation, and other mechanisms. Green tea EGCG effectively reduces adipose tissue mass and ameliorates plasma lipid profiles in high-fat diet-induced obese mice. These effects might be at least partially mediated via regulation of the expression of multiple genes involved in adiposeness, lipolysis, beta-oxidation and thermogenesis in white adipose tissue.
Chen et al. (2009) demonstrated the mechanisms by which tea and EGCG may improve glucose tolerance and support role for these compounds in obesity prevention. These include suppression of adipocyte differentiation and fatty acid uptake into adipose tissue, while increasing fat synthesis and oxidation by the liver, without inducing hepatic fat accumulation by green tea as well as black tea. In contrast, EGCG increased markers of thermogenesis and differentiation in adipose tissue, while having no effect on liver or muscle tissues at this dose.
Various other mechanisms have also been proposed for the action of green tea components on body fat such as modulation of dietary fat absorption and metabolism, increased glucose utilization, decreased de novo lipogenesis, enhanced vascular responsiveness, and anti-oxidative effects. While reviewing the evidence for the mechanism of action of green tea catechin on weight loss, Rains et al. (2011) finds the predominating hypothesis to be its influence on sympathetic nervous system (SNS) activity, increasing energy expenditure and promoting the oxidation of fat.
Caffeine, naturally present in green tea, also influences SNS activity, and may act synergistically with catechin to increase energy expenditure and fat oxidation. Other potential mechanisms include modifications in appetite; up-regulation of enzymes involved in hepatic fat oxidation, and decreased nutrient absorption.
EGCG alone has the potential to increase fat oxidation in men and may thereby contribute to the anti-obesity effects of green tea.
Another compound in tea, caffeine has also been found to have an effect on body fat. High caffeine intake was associated with weight loss through thermogenesis and fat oxidation, and with suppressed leptin in women. Whereas among the habitual low caffeine consumers, green tea-caffeine mixture improved weight management, partly through thermogenesis and fat oxidation.
Green tea (epigallocatechin gallate + caffeine) and protein each were shown to improve body weight maintenance after weight loss. The green tea-caffeine mixture, as well as the high protein diet, improved weight maintenance independently through thermogenesis, fat oxidation, sparing fat free mass. Catechins or an epigallocatechin gallate (EGCG)-caffeine mixture have a small positive effect on weight loss and weight management.
The results suggested that habitual caffeine intake and ethnicity may be moderators, as they may influence the effect of catechins. According to Diepvens et al. (2007) both green tea catechins and caffeine, may act through inhibition of catechol O-methyl-transferase, and inhibition of phosphodiesterase. Here, the mechanisms may also operate synergistically. In addition, tea catechins have anti-angiogenic properties that may prevent development of overweight and obesity. Furthermore, the sympathetic nervous system is involved in the regulation of lipolysis.
Thavanesan (2011) on reviewing the available literature on green tea suggests a multi model approach, involving simultaneous inhibition of the enzymes catechol- O-methyltransferase, acetyl-CoA carboxylase, fatty acid synthase and impeding absorption of fat via the gut. Though the available evidence supports a role of green tea in weight loss, But the author feels the extent of the effects obtained is still subject to debate, and requires more objective quantification in future research.
The anti-obesity effects of green tea could be variety specific. Oolong tea is traditionally reported to have anti-obesity and hypolipidaemic effects as it prevented the obesity and fatty liver induced by a high-fat diet. Caffeine in the water extract of oolong tea enhanced noradrenaline-induced lipolysis in fat cells without a concomitant increase in hormone-sensitive lipase activity and also accelerated the hormone-induced lipolysis in a cell-free system consisting of lipid droplets and HSL, but not in the cell-free system with sonicated lipid droplets and HSL.
Oolong tea extract also inhibited pancreatic lipase activity and thereby inhibited lipid digestion. Thus, Han et al. (1999b) suggested that oolong tea may be an effective crude drug for the treatment of obesity and fatty liver caused by a high-fat diet.
He et al. (2009) observed on feeding with 8 g of oolong tea a day for 6 weeks, a decrease of more than 1 kg in body weight in 70 per cent of the severely obese subjects, including 22 per cent who lost more than 3 kg. Similarly, 64 per cent of the obese subjects and 66 per cent of the overweight subjects lost more than 1 kg during the experiment, and the subcutaneous fat content decreased in 12 per cent of the subjects. Oolong tea could decrease body fat content and reduce body weight by improving lipid metabolism. Thus, prolonged consumption of oolong tea may prevent obesity.
Phellinus baumii extract (PBE) in high-fat diet (HFD)-fed 8-week-old male mice significantly reduced body weight gain, hepatic lipid concentrations, and fat accumulation in epididymal adipocytes. The anti-obesity and hypo-lipidemic effects appear to be partly mediated by suppressing plasma and hepatic fat accumulation through the inhibition of enzymes associated with hepatic and intestinal lipid absorption and synthesis.