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Effect of green tea extract on lipid profile in patients with type 2 diabetes mellitus: A systematic review and meta-analysis.
Asbaghi, O, Fouladvand, F, Moradi, S, Ashtary-Larky, D, Choghakhori, R, Abbasnezhad, A
Diabetes & metabolic syndrome. 2020;(4):293-301
Abstract
BACKGROUND Previous studies have indicated controversial results regarding the efficacy of green tea extract (GTE) in improving the lipid profile of type 2 diabetes mellitus (T2DM) patients. We aimed to conduct a systematic review and meta-analysis to pool data from randomized controlled trials (RCTs). METHODS A systematic search was performed in Web of Science, PubMed, and Scopus databases, without any language and time restriction until August 2019, to retrieve the RCTs which examined the effects of GTE on serum concentrations of high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglyceride (TG) or total cholesterol (TC) in T2DM patients. Meta-analyses were carried out using a random effects model. I2 index was used to evaluate the heterogeneity. RESULTS Initial search yielded 780 publications. Of these, seven studies were eligible. The supplementary intake of GTE improved lipid profile by reducing serum TG concentrations in patients with T2DM. Meanwhile, subgroup analyses based on duration of interventions (≤8 and > 8 weeks) and intervention dosage (≤800 and > 800 mg/day) showed that the GTE supplementation longer than 8 weeks and in doses >800 mg/day resulted in a significant decrease in serum TG concentrations. Furthermore, intervention longer than 8 weeks with doses lower than 800 mg/day resulted in a significant reduction in serum TC concentrations. CONCLUSION In conclusion, present systematic review and meta-analysis revealed that the supplementary intake of GTE may improve lipid profile by reducing serum concentrations of TG in patients with T2DM. Furthermore, the results of our stratified analyses suggested that long-term GTE intervention may reduce serum concentrations of TG and TC.
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Effects of tea consumption on metabolic syndrome: A systematic review and meta-analysis of randomized clinical trials.
Liu, W, Wan, C, Huang, Y, Li, M
Phytotherapy research : PTR. 2020;(11):2857-2866
Abstract
The metabolic syndrome (MetS) is one of the major health hazards and an epidemic worldwide. There is no known best remedy has been defined yet. In the current investigation, we designed a meta-analysis of randomized clinical trials (RCTs) to evaluate the beneficial effects of tea consumption in alleviating metabolic syndromes. Herein, we accumulated the relevant literature available on PubMed and EMBASE databases from January, 2000 to August, 2019. RCTs bearing impact factor of at least 1 or more were studied for the effect of tea consumption on MetS. This meta-analysis suggested that tea consumption has beneficial effects on diastolic blood pressure (DBP), and this finding was characterized of all types of tea in the current study and also for body mass index (BMI) value. Furthermore, this analysis also found that black tea consumption has protective effects on systolic SBP, green tea reduces the incidence of diabetes and lower the level of low-density lipoprotein (LDL) cholesterol. These functions required BMI value at least 28 or higher. The meta data led us to conclude that tea consumption have protective effects on MetS, however, different types of tea might have different protective mechanisms on MetS, but, exact mechanisms are not yet clear and needs to be explored.
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Efficacy of tea catechin-rich beverages to reduce abdominal adiposity and metabolic syndrome risks in obese and overweight subjects: a pooled analysis of 6 human trials.
Hibi, M, Takase, H, Iwasaki, M, Osaki, N, Katsuragi, Y
Nutrition research (New York, N.Y.). 2018;:1-10
Abstract
This post hoc pooled analysis assessed the effectiveness of green tea catechins (GTC) to reduce the risk of metabolic syndrome (MetS) associated with abdominal fat reduction, because previous findings are unclear. Data were pooled from six human trials (n=921, 505 men) comparing the effects of GTC-containing beverages (540-588 mg GTC/beverage) and a placebo beverage. Outcome measures were abdominal fat [total fat area (TFA), visceral fat area (VFA), subcutaneous fat area (SFA)], and MetS risk. We estimated mean changes from baseline and calculated confidence intervals (CI) to assess reductions in abdominal fat accumulation and MetS improvement. Subclass analyses were performed by classifying subjects as Pre-MetS or MetS at trial initiation. Additional subclass analyses were performed with Pre-MetS and MetS subjects further stratified according to whether GTC intake reduced TFA, VFA, or SFA. Consumption of GTC-containing beverages for 12 weeks significantly reduced TFA (-17.7cm2, 95%CI: -20.9 to -14.4), VFA (-7.5cm2, 95%CI: -9.3 to -5.7), SFA (-10.2cm2, 95%CI: -12.5 to -7.8), body weight, body mass index, and waist circumference; and improved blood pressure. Subclass analyses of Pre-MetS and MetS subjects showed improved MetS in the GTC group [odds ratio (OR), 1.67; 95%CI: 1.08-2.57]. The ORs for improved MetS in the TFA- and VFA-reduced groups were 2.79 (95%CI: 1.28-6.09) and 4.36 (95%CI: 2.03-9.39), respectively. Continual consumption of GTC-containing beverages reduced abdominal fat and improved MetS, suggesting its potential to prevent diabetes and cardiovascular disease. Additional large-scale intervention trials are needed to evaluate the effects of GTC on the risk of MetS in high-risk populations.
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Green Tea and Bone Marrow Transplantation: From Antioxidant Activity to Enzymatic and Multidrug-resistance Modulation.
Peluso, I, Palmery, M, Vitalone, A
Critical reviews in food science and nutrition. 2016;(14):2251-60
Abstract
Epigallocatechin-3-gallate (EGCG), the main flavonoid of green tea (GT), could play an active role in the prevention of oxidative-stress-related diseases, such as hematologic malignancies. Some effects of EGCG are not imputable to antioxidant activity, but involve modulation of antioxidant enzymes and uric acid (UA) levels. The latter is the major factor responsible of the plasma non-enzymatic antioxidant capacity (NEAC). However, hyperuricemia is a frequent clinical feature caused by tumor lysis syndrome or cyclosporine side effects, both before and after bone marrow transplantation (BMT). Besides this, food-drug interactions could be associated with GT consumption and could have clinical implications. The molecular mechanisms involved in the redox and drug metabolizing/transporting pathways were discussed, with particular reference to the potential role of GT and EGCG in BMT. Moreover, on reviewing data on NEAC, isoprostanes, uric acid, and various enzymes from human studies on GT, its extract, or EGCG, an increase in NEAC, without effect on isoprostanes, and contrasting results on UA and enzymes were observed. Currently, few and contrasting available evidences suggest caution for GT consumption in BMT patients and more studies are needed to better understand the potential impact of EGCG on oxidative stress and metabolizing/transporting systems.
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Weight reduction effect of Puerh tea in male patients with metabolic syndrome.
Yang, TY, Chou, JI, Ueng, KC, Chou, MY, Yang, JJ, Lin-Shiau, SY, Hu, ME, Lin, JK
Phytotherapy research : PTR. 2014;(7):1096-101
Abstract
Puerh tea has been proposed to promote weight loss and favorably modify glucose, insulin and blood lipids. This study tested the effect of daily Puerh tea consumption for 3 months on weight and body mass index (BMI), and select metabolic parameters. The effect of daily Puerh tea intake on weight, BMI and changes in glucose, HbA1c and lipids was evaluated in patients with metabolic syndrome. The patients (N = 70) were randomized into two groups: those taking Puerh tea extract capsule (333 mg Puerh tea extract) three times a day and those taking a placebo tea for 3 months. There was a decrease in body weight of 1.3 kg in the Puerh tea group (p = 0.077) versus 0.23 kg in the placebo arm (p = 0.186). There was also a slight decrease in BMI 0.47 kg/m(2) in the Puerh tea group (p = 0.076) versus 0.09 kg/m(2) in the placebo arm (p = 0.185), suggesting a trend of weight change, but without statistical significance. Subgroup analysis of the male patients demonstrated statistically significant improvements in body weight reduction (p = 0.004) and BMI (p = 0.004). However, the change in other metabolic parameters (cholesterol or triglyceride) or HbA1c was not statistically significant. Intake of Puerh tea for 3 months was associated with a slight reduction in body weight and BMI, especially in the male patients. Therefore, daily Puerh tea consumption may be an alternative choice to modify body weight.
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Effectiveness of green tea in a randomized human cohort: relevance to diabetes and its complications.
Toolsee, NA, Aruoma, OI, Gunness, TK, Kowlessur, S, Dambala, V, Murad, F, Googoolye, K, Daus, D, Indelicato, J, Rondeau, P, et al
BioMed research international. 2013;:412379
Abstract
Epidemiological studies have argued that green tea could mitigate diabetes and its complications. This study investigated the phytophenolic profile of Mauritian green tea and its antioxidant propensity. The effect of green tea on the risk factors: waist-hip ratio, glucose level, arterial pressure, antioxidant status, and alanine aminotransferase (ALT) in prediabetics was assessed. The experimental group consumed 3 cups of green tea daily for 14 weeks followed by a 2-week washout period. The control group followed a water regimen. Green tea contained high level of phenolics related to its antioxidant power. Green tea suppressed waist-hip ratio of women from a significant increase and suppressed mean arterial pressure of men and women from a significant decrease after week 14. It reduced ALT level in women by 13.0% (P < 0.1) while increasing the antioxidant potential of men and women sera by 2.7% (P < 0.1) and 5.1% (P < 0.1). The study timescale may have been too short to enable demonstration of effects on fasting plasma glucose and HbA1c outcomes. Green tea regimen could form part of a healthy lifestyle that might ameliorate features of metabolic syndrome and subsequent risks for diabetes and its complications. This trial is registered with ClinicalTrials.gov NCT01248143.
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Green tea minimally affects biomarkers of inflammation in obese subjects with metabolic syndrome.
Basu, A, Du, M, Sanchez, K, Leyva, MJ, Betts, NM, Blevins, S, Wu, M, Aston, CE, Lyons, TJ
Nutrition (Burbank, Los Angeles County, Calif.). 2011;(2):206-13
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Abstract
OBJECTIVE Green tea (Camellia sinensis) has shown to exert cardioprotective benefits in observational studies. The objective of this clinical trial was to assess the effects of green tea on features of metabolic syndrome and inflammation in obese subjects. METHODS We conducted a randomized controlled trial in obese subjects with metabolic syndrome. Thirty-five subjects [(mean ± SE) age 42.5 ± 1.7 y, body mass index 36.1 ± 1.3 kg/m(2)] completed the 8-wk study and were randomly assigned to receive green tea (4 cups/d), green tea extract (2 capsules and 4 cups water/d), or no treatment (4 cups water/d). Both the beverage and extract groups had similar dosing of epigallocatechin-3-gallate, the active green tea polyphenol. Fasting blood samples were collected at screening, 4 and 8 wk of the study. RESULTS Green tea beverage or extract supplementation did not significantly alter features of metabolic syndrome or biomarkers of inflammation including adiponectin, C-reactive protein, interleukin-6, interleukin-1β, soluble vascular cell adhesion molecule-1, soluble intercellular adhesion molecule-1, leptin, or leptin:adiponectin ratio. However, both green tea beverage and extracts significantly reduced plasma serum amyloid alpha versus no treatment (P < 0.005). CONCLUSION This study suggests that the daily consumption of green tea beverage or extracts for 8 wk was well tolerated but did not affect the features of metabolic syndrome. However, green tea significantly reduced plasma serum amyloid alpha, an independent cardiovascular disease risk factor, in obese subjects with metabolic syndrome.