The half maximal effective concentration EC50 values in antioxidant activity and reducing power of green tea extracts were 2. Oxidative stress and endothelial dysfunction are closely associated with hypertension and insulin resistance IR in metabolic syndrome MetS.

There was study showing that decaffeinated green tea extracts GTE reduced the formation of reactive oxygen species ROS and nicotinamide adenine dinucleotide phosphate NADPH oxidase activity, and stimulated phosphorylation of endothelial nitric oxide synthase eNOS and Akt in the aorta of a rat model of MetS, which resulted in improved endothelial dysfunction and IR, and eventually lowered blood pressure BP.

Furthermore, decaffeinated-GTE significantly reduced vascular ROS formation and NADPH oxidase activity, and improved endothelium dependent relaxation in the thoracic aorta of the tested rats.

Immunohistochemical staining tests showed that the expression of p47 and p22phox NADPH oxidase subunits were suppressed by decaffeinated-GTE, but phosphorylation of eNOS and Akt in the immunoblotting of aortas were stimulated [7].

Though black tea and green tea had different composition of tea polyphenpls, both of them attenuated blood pressure increases through their antioxidant properties in stroke-prone spontaneously hypertensive rats SHRSP. When SHRSP was fed with black tea polyphenols BTP, containing 3.

The GTP significantly increased catalase expression. The phosphorylated myosin light chain MLC-p expression in the aorta was significantly decreased by BTP and GTP [8]. Out-of-control ROS signaling is one of the key events in the pathogenesis of endothelial dysfunction and essential hypertension.

Tea polyphenols regulated ROS-related protein expression and might be beneficial in alleviating angiotensin Ang II-induced hyperpermeability, preventing endothelial cell dysfunction and development of CVD, including hypertension.

Ying et al. found that tea polyphenols decreased the production of ROS via regulation of the protein expression of NADPH oxidase in bovine carotid artery endothelial cells BCAECs. Both GTP and BTP down-regulated the expression of NADPH oxidase subunits p22phox and p67phox while up-regulating catalase expression p Metabolic syndrome MetS is a group of risk factors that occur together and increase the risk for CVD and diabetes, including insulin resistance IR , obesity, hypertriglyceridemia, hypercholesterolemia and hypertension.

Hypertension and IR in Sprague-Dawley SD rats can be induced by feeding a fructose-rich diet. Wu et al. examined the effects of green tea supplementation 0.

It showed that the fructose group developed fasting hyperglycemia, hyperinsulinemia, and elevated blood pressure. Insulin-stimulated glucose uptake and insulin binding of adipocytes were significantly reduced, and the glucose transporter IV GLUT IV content of adipocytes also decreased.

All of these metabolic defects, including IR and BP were improved by the green tea supplementation [12]. It is considered that the amelioration of IR by green tea is associated with the increased expression of GLUT IV.

EGCG is considered to augment metabolic and vascular actions of insulin. Like enalapril an angiotensin converting enzyme inhibitor , acute action of EGCG stimulated the production of nitric oxide from endothelium, resulting in improvement of insulin sensitivity and increase in plasma adiponectin levels in SHR a model of metabolic syndrome with hypertension, insulin resistance, and overweight [13].

In a double-blind, placebo-controlled trial, 56 obese, hypertensive subjects were randomized to receive a daily supplement of 1 capsule containing either mg of green tea extract GTE or a matching placebo.

After 3 months of supplementation, both systolic and diastolic blood pressures had significantly decreased in the GTE group as compared with the placebo group p Hasegawa et al. Zhang et al. reported that visceral fat area, BW, and body fat were reduced significantly by drinking a mL bottle of catechin-enriched green tea beverage which contained The preventive mechanism of tea on obesity was related to inhibition of pancreatic lipase PL and regulation of expressions of proteins or related genes.

Grove et al. reported that supplementation with feed containing 0. Matrix metalloproteinases MMPs consist of a multigene family of zinc-dependent extracellular matrix ECM remodeling endopeptidases implicated in pathological processes. The mRNA expression of both IL-6 and MMP-9 increased significantly in a time-dependent manner in THP-1 macrophages cultured in normocholesterolaemic hypertensive sera p It is known that plasminogen activator inhibitor-1 PAI-1 plays a pivotal role in CVD including arteriosclerosis and hypertension.

The high PAI-1 plasma levels were associated with coronary heart disease. Liu et al. showed that the expression and secretion of PAI-1 in endothelial cells and bovine aortic endothelial cells were significantly reduced by GTP treatment in a time dependent and dose-dependent manner.

The GTP-induced inhibitory effect was associated with an increased activation of the protein kinase Akt [21]. Caveolin-1 Cav-1 , a negative regulator of endothelial nitric oxide synthase eNOS , influences various aspects of the cardiovascular functions.

GTP 0. Hypercholesterolemia is the presence of higher concentrations of low density lipoprotein LDL and lower concentrations of functional high density lipoprotein HDL in the blood, which are strongly associated with CVD because these promote atheroma development in arteries atherosclerosis.

A study on obese women showed that oral administration of a capsule containing mg green tea extract three times per day for 12 weeks had significant reduction in LDL-cholesterol and triglyceride, but marked increase in the levels of HDL-cholesterol, adiponectin and ghrelin, though the decrease in BW was not statistically significant [23].

Diabetes and obesity are common metabolic disorders which are associated with the development of CVD. Angiotensin is a peptide hormone that causes vasoconstriction and a subsequent increase in blood pressure, and it is a part of the renin-angiotensin system, which is a major target for drugs that lower blood pressure.

It is considered that the effect of green tea on hypertension might be related to its inhibition of angiotensin converting enzyme ACE. Liang et al. showed that intragastric administration at dosages 0.

The inhibitory effect of tea on ACE depended on chemical composition of the tea. The GABA gamma-aminobutyric acid -rich tea was more effective in preventing the development of hypertension in Dahl salt-sensitive rats fed with a high salt diet [27].

Endothelial dysfunction is a systemic disorder and a key variable in the pathogenesis of atherosclerosis and it is regarded as an integrated index of all atherogenic and atheroprotective factors present in an individual. NO regulates vascular tone, proliferation of vascular smooth muscle cells and hemostasis.

Disruptions in the physiological production of NO triggers endothelial cell dysfunction, resulting in an increased risk of CVD.

The physiological increase in NO bioavailability by green tea is considered to be promising for the prevention and therapy of CVD. Cardiac hypertrophy is a thickening of the heart muscle myocardium which results in a decrease in size of the chamber of the heart, including the left and right ventricles.

It is usually the response to stress or disease such as hypertension, heart muscle injury, heart failure or neurohormones. GTE might block the development of cardiac hypertrophy in an animal model of chronic renal failure.

Male SD rats were subjected to sham or remnant kidney surgery and given green tea extract GTE, 0. The administration of GTE at 0. There was study showed that EGCG inhibited Ang IIstimulated VSMC hypertrophy through the JNK signaling pathway at both transcriptional and posttranslational levels [31].

Prevention of cardiac remodeling due to increased pressure overload is important to reduce morbidity and mortality. EGCG prevented the development of left ventricular concentric hypertrophy by pressure overload.

Cardiac hypertrophy can be induced by suprarenal transverse abdominal aortic constriction AC in rats. Green tea both prevented and reversed the cardiovascular remodeling and metabolic changes seen in high carbohydrate-fed rats.

High carbohydrate diet-fed rats showed glucose intolerance, hypertension, mild left ventricular hypertrophy and etc. Administration of green tea to high carbohydrate diet-fed rats prevented and reversed glucose intolerance and the increased systolic blood pressure, left ventricular wet weight, interstitial collagen and passive diastolic stiffness [33].

Green tea gavage at dosage 0. Transaortic abdominal aortic constriction TAC decreased mitochondrial DNA copy number and the activity of respiratory chain complexes I, III and IV in rats, but these decreases could be reversed by EGCG treatment [35]. Kokaze et al. Irrespective of antihypertensive drug treatment, the association between MtC genotype and hypertension was dependent on green tea consumption [36].

There were conflicting results about the effect of drinking of tea on CVD and BP [37]. A case-control study carried out among nulliparous pregnant women in Quebec, Canada showed that persistent tea drinking during pregnancy may be associated with an increased risk of pre-eclampsia [38].

Trial shows electroacupuncture - acupuncture that uses low-intensity electrical pulses - can lower high blood pressure for up to 6 weeks in untreated…. Caffeine has been linked to increases in blood pressure, and a new study suggests that it may interfere with blood pressure testing and treatment.

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Medical News Today. Health Conditions Health Products Discover Tools Connect. Research reveals how tea may lower blood pressure. By James Kingsland on March 11, — Fact checked by Rita Ponce, Ph.

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Changes in other parameters did not reach statistical significance. The meta-analysis also suggests that green tea catechins may improve total and low-density lipoprotein cholesterol.

Abstract Purpose: Although previous literature has reported that regular green tea consumption may improve blood pressure, the evidence from these studies is not consistent. Publication types Meta-Analysis Review Systematic Review.