Green Tea Extract Supplement With Egcg for Weight Loss Reviews
Abstruse
Background: Dark-green tea catechins (GTCs) with or without caffeine take been studied in randomized controlled trials (RCTs) for their outcome on anthropometric measures and accept yielded alien results.
Objective: The objective was to perform a systematic review and meta-analysis of RCTs of GTCs on anthropometric variables, including body mass index (BMI), body weight, waist circumference (WC), and waist-to-hip ratio (WHR).
Blueprint: A systematic literature search of MEDLINE, EMBASE, CENTRAL, and the Natural Medicines Comprehensive Database was conducted through April 2009. RCTs that evaluated GTCs with or without caffeine and that reported BMI, trunk weight, WC, or WHR were included. The weighted mean deviation of change from baseline (with 95% CIs) was calculated by using a random-effects model.
Results: Fifteen studies (north = 1243 patients) met the inclusion criteria. On meta-analysis, GTCs with caffeine decreased BMI (−0.55; 95% CI: −0.65, −0.forty), torso weight (−1.38 kg; 95% CI: −one.70, −i.06), and WC (−one.93 cm; 95% CI: −2.82, −1.04) but not WHR compared with caffeine alone. GTC ingestion with caffeine also significantly decreased trunk weight (−0.44 kg; 95% CI: −0.72, −0.15) when compared with a caffeine-free command. Studies that evaluated GTCs without concomitant caffeine administration did non testify benefits on whatsoever of the assessed anthropometric endpoints.
Conclusions: The administration of GTCs with caffeine is associated with statistically significant reductions in BMI, torso weight, and WC; however, the clinical significance of these reductions is modest at best. Current data practise not suggest that GTCs alone positively alter anthropometric measurements.
INTRODUCTION
Being overweight or obese, divers every bit a body mass index (BMI; in kg/m2) betwixt 25 and 30 and a BMI >xxx, respectively (ane), is associated with a college risk of developing cardiovascular disease and blazon two diabetes mellitus (2) and increased bloodshed (3, iv). Virtually two-thirds of the Usa developed population is overweight (v) and ≈26% are obese, with some states reporting obesity rates equally high as 33% (half dozen). Co-ordinate to the clinical guidelines regarding overweight and obesity published past the National Institutes of Health, weight loss (and subsequent BMI reduction) is recommended to decrease blood pressure, serum lipids, and glucose variables to ultimately decrease the risk of cardiovascular affliction and diabetes (1). Therefore, body weight loss remains an important target for disease prevention.
There is a growing trunk of research showing that intake of green tea catechins (GTCs) may reduce BMI and body weight and suggests that the risk of cardiovascular disease may also be modified (7, viii). Catechins found in light-green tea include epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), epigallocatechin gallate (EGCG), gallocatechin (GC), catechin gallate (CG), gallocatechin gallate (GCG), and catechin (C) (ix). EGCG is believed to be the most pharmacologically agile catechin and constitutes >50% of the full catechin content in well-nigh dark-green tea products (vii). Potential mechanisms past which GTCs exert these anthropometric furnishings involve inhibition of adipocyte differentiation and proliferation (10), reduced fat absorption (eleven), inhibition of catechol-o-methyl-transferase (10), increased energy expenditure (8), and increased utilization of fatty (11).
In add-on to GTCs, greenish tea also naturally contains caffeine (nine). The use of caffeine may also contribute to changes in anthropometric measures through increased energy expenditure (12, 13) or increased thermogenesis (13). Because of caffeine'due south contained effects, the combination of GTCs with caffeine may exist able to provide condiment or even synergistic do good over GTCs alone.
Randomized controlled trials have been conducted (14–28) to assess the event of GTCs with or without caffeine on anthropometric variables, but yielded conflicting results and had only pocket-sized sample sizes. Therefore, we performed a systematic review and meta-analysis of randomized clinical trials to narrate the relation between GTCs with and without caffeine and changes in anthropometric variables, including BMI, trunk weight, waist circumference (WC), and waist-to-hip ratio (WHR).
METHODS
A systematic literature search was conducted through Apr 2009 in the following databases: MEDLINE (showtime 1950) (http://www.pubmed.gov), EMBASE (offset 1990) (http://www.embase.com), Cochrane CENTRAL (indexed April 2009) (http://mrw.interscience.wiley.com/cochrane/cochrane_clcentral_articles_fs.html), and the Natural Medicines Comprehensive Database (http://www.naturaldatabase.com/). A search strategy was performed combining the Medical Subject field Headings and the following text keywords: tea, light-green tea, green tea extract, catechin, EGCG, tea polyphenols, theaflavin, or Camelia sinensis with BMI, body weight, WC, waist-to-hip ratio, metabolic syndrome, weight loss, obesity, or overweight. No linguistic communication restrictions were imposed and indistinguishable citations were removed. In add-on, a manual search of references from primary or review articles was performed to identify boosted relevant trials.
Trials were included in the assay if they were randomized and evaluated the use of GTCs with or without caffeine and reported information on at to the lowest degree one of the following endpoints: 1) BMI, 2) torso weight, three) WC, or 4) WHR. Both parallel and crossover trials were eligible for inclusion, simply ultimately no eligible crossover trials were identified. In trials for which at that place was more than one published report on the same population of patients, the data were deemed for only once simply were referenced multiple times as necessary. For one report (26), for which insufficient data for a meta-analysis were provided, the author was contacted via E-mail with a request to provide additional information, to which the writer responded with usable body weight data. Three investigators (OJP, LJM, and ML) reviewed potentially relevant manufactures independently and abstracted the necessary information with differences resolved through discussion.
Validity assessment was performed by two investigators (LJM and ML) using the American Dietetic Clan Research Design and Implementation Checklist for main inquiry (29). This checklist includes 10 validity questions covering the following domains: a clear argument of the research question, bias-free subject selection, comparable groups, clarification of withdrawal handling, blinding, detailed description of protocol, articulate definition of outcomes, advisable statistical analysis, conclusions supported by information, and unlikely bias due to sponsorship or funding. Each of the 10 questions has a series of subquestions that assist in answering the overall question equally either yeah, no, or unclear. The 4 questions pertaining to bias-complimentary subject field selection, comparable groups, detailed clarification of protocol, and clear definition of outcomes received the most consideration when evaluating the overall report quality. The report was rated as positive if the 4 major criteria were met along with ≥i other "yes," neutral if the iv major criteria were not all "yes," and minus if most (≥half-dozen) questions were answered equally "no."
To business relationship for the possible confounding effect of caffeine on our results, we conducted 3 separate analyses. The kickoff analysis evaluated trials that studied GTCs with caffeine compared with a caffeine-matched command, the second evaluated GTCs with caffeine compared with a caffeine-free control, and the third evaluated caffeine-costless GTCs compared with a caffeine-free control. For each analysis, the hateful change in BMI, trunk weight, WC, and WHR from baseline were treated as continuous variables, and the weighted mean differences (WMDs) were calculated as the differences between the mean in the GTC and control groups. A DerSimonian and Laird random-effects model (a variation on the changed variance method, which incorporates an assumption that the different studies are estimating unlike, nonetheless related, treatment effects) was used to calculate the WMD with accompanying 95% CIs (xxx). Internet changes in each of these study variables were calculated as the difference (catechin minus command) in the changes (baseline minus follow-upwardly) in these mean values (also referred to every bit the change score). In instances in which variances for net changes were non reported direct, they were calculated from confidence intervals, P values, or individual variances for catechin and control groups. For trials in which variance for paired differences were reported separately for each group, nosotros calculated a pooled variance for net alter using standard methods. When the variance for paired differences was non reported, we calculated it from variances at baseline and at the end of follow-upward. As suggested by Follmann et al (31), nosotros assumed a correlation coefficient of 0.5 betwixt initial and final values. For one study (23) in which the medians and interquartile ranges were reported, values were assumed to approximate ways and 95% CIs (32). The statistical analysis was performed by using StatsDirect software (version ii.4.6, 2008; StatsDirect Ltd, Cheshire, United kingdom of great britain and northern ireland). A P value <0.05 was considered statistically meaning for all analyses. Statistical heterogeneity was assessed by using the I 2 statistic, where values of 25%, 50%, and 75% were considered to have depression, medium, and high statistical heterogeneity, respectively. Visual inspection of funnel plots and Egger's weighted regression statistics were used to determine the presence of publication bias. For analyses in which pregnant publication bias was detected, trim-and-fill analyses were conducted by using MIX for Meta-Analysis software (version 1.7, 2008) (33, 34) to assess its potential effect on our results.
RESULTS
Study characteristics
Of the 341 nonduplicate citations retrieved through the search strategy, 46 full-text articles were identified for detailed evaluation (Figure 1). Through a transmission reference search of principal and review articles, 8 additional articles were retrieved for detailed evaluation. From the overall pool of full-text articles, 25 did not study relevant outcomes, 9 were non randomized controlled trials, two did not evaluate GTCs, and 2 repeated data from some other report (35, 36). Iii studies reported anthropometric outcomes (37–39) but were considered nonrelevant considering both investigated weight maintenance subsequent to a depression-calorie diet and exercise regimen rather than weight loss resulting from GTCs.
Figure one
QUOROM (Quality of Reporting of Meta-analyses) flow diagram of study identification, inclusion, and exclusion of randomized controlled trials that evaluated the effect of green tea on anthropometric variables.
Effigy one
QUOROM (Quality of Reporting of Meta-analyses) flow diagram of report identification, inclusion, and exclusion of randomized controlled trials that evaluated the effect of green tea on anthropometric variables.
A total of 15 trials (n = 1243) met the inclusion criteria ( Tabular array i). Of the 15 trials included, 7 trials (n = 600) evaluated GTCs with caffeine compared with a caffeine-matched control (14–20), 6 trials (n = 524) evaluated GTCs with caffeine compared with a caffeine-costless control (21–26), and 2 trials (n = 119) evaluated caffeine-costless GTCs compared with a caffeine-costless control (27, 28). Patients were followed for 8 to 24 wk (median: 12 wk). Treatment groups received GTCs [dose range: 576–714 (median: 588) mg/d in the GTCs with caffeine compared with caffeine-matched command group trials; 141–1207 (median: 474) mg/d in the GTCs with caffeine compared with caffeine-free control group trials; and 282–548 (median: 415) mg/d in the caffeine-costless trials] in diverse dosage forms, such as greenish tea extract capsules or dark-green tea beverages. 4 trials (14, 16, 17, 19) limited additional tea or catechin-rich nutrient consumption other than study materials. Boosted caffeine intake was regulated in iv studies, with caffeine being restricted to no more than 2 or 3 beverages per day (xiv, xv), being completely prohibited (23), or requiring a standardized corporeality in both intervention and control groups (24). Ii trials (15, 28) required concurrent practice for both intervention and control groups. Results of the quality rating of trials are also presented in Table ane.
TABLE ane
Characteristics of included randomized controlled trials of green tea catechins 1
| Full sample size | Study pattern | ADA quality rating | Population | Baseline characteristics (I, C) | Follow-upward | Tea group | Command group | Catechin components | Concurrent lifestyle modifications |
| wk | mg | ||||||||
| Light-green tea catechins with caffeine compared with caffeine-matched control | |||||||||
| Frank et al, 2009 (14), n = 33 | Double-blinded, parallel | + | Healthy men, historic period eighteen–55 y, BMI 22–32 | BMI: 26.7, 25.4 | 3 | Aqueous GTE capsule (714 mg catechins), 114 mg caffeine | Placebo (maltodextrin) capsules with 114 mg caffeine | EGC: 282; EGCG: 150; ECG:84; GC: 54; GCG: 48; EC: 30; CG: 18; C: six | Limit daily tea and coffee consumption to ≤three cups (711 mL) simply maintain normal nutrition and exercise |
| Maki et al, 2009 (fifteen), due north = 129 | Double-blinded, parallel | + | Age 21–65 y, WC ≥90/87 (men/women), total cholesterol ≥5.2 mmol/50 | BMI: 32.ii, 32.2; WT: 95.i, 95.1; WC: 108.2, 108.9 | 12 | 500 mL light-green tea potable (625 mg catechins), 39 mg caffeine | Placebo drink containing 0 mg catechins, 39 mg caffeine, same number of calories | GC: 51.8; GC: 207.5; C: nineteen.2; EC: 53.9; EGCG: 214.4; GCG: 15.iv; ECG: 56.5; CG: 6 | Limit to ≤2 caffeinated beverages per solar day (excluding study beverage); normal diet; ≥180 min practise weekly, including 3 supervised exercise sessions per week |
| Nagao et al, 2009 (16), n = 43 | Double-blinded, parallel | + | T2DM (no insulin therapy, stable medication and diet) | BMI: 25.6, 24.0; WT: 61.8, 60.0; WC: 89.8, 86.5; WHR: 0.93, 0.91 | 12 | 340 mL greenish tea beverage (583 mg catechins), seventy mg caffeine | 340 mL green tea drinkable containing 96 mg catechins and 70 mg caffeine | Enriched tea: C: 42.8; CG: 40.ane; GC: 127.5; GCG: 139.7; EC: 32.3; ECG: xxx.9; EGC: 69.four; EGCG: 100.iii | Normal diet; no catechin-rich foods that might change carbohydrate or lipid metabolism |
| Control tea: C: 6.1; CG: 4.iv; GC: 23.8; GCG: 24.ane; EC: 4.eight; ECG: v.i; EGC: 11.2; EGCG: 16.7 | |||||||||
| Matsuyama et al, 2008 (17), n = 40 | Double-blinded, parallel | + | Children aged 6–16 y, BMI >28 or diagnosis of obesity | BMI: 27.ii, 27.four; WT: 65.5, 65.4; WC: 89.2, 88.9; WHR: 0.95, 0.94 | 24 | 340 mL green tea beverage (576 mg catechins), 80 mg caffeine | 340 mL green tea beverage containing 75 mg catechins, 78 mg caffeine | Enriched tea: C: 39.8; CG: 36.7; GC: 128.9; GCG: 135.7; EC: 29.2; ECG: 32; EGC: 71.four; EGCG: 102.3 | No backlog lipids, sugars, or caffeine; no catechin-rich foods; no "foods that reduce backlog adiposity;" maintain usual practice |
| Control tea: C: five.8; CG: 3.7; GC: 20.4; GCG: 17.3; EC: iv.4; ECG: three.7; EGC: 7.8; EGCG: 11.6 | |||||||||
| Nagao et al, 2007 (18), n = 240 | Double-blinded, parallel | + | Age 25–55 y, BMI 24–xxx, and/or WC eighty–94 | BMI: 26.9, 26.seven; WT: 73.3, 72.i; WC: 87.2, 86.5; WHR 2 : 0.89, 0.89 | 12 | 340 mL dark-green tea potable (583 mg catechins), 70 mg caffeine | 340 mL greenish tea beverage containing 96 mg catechins and 70 mg caffeine | Enriched tea: C: 42.8; CG: 40.i; GC: 127.v; GCG: 139.7; EC: 32.3; ECG: xxx.9; EGC: 69.4; EGCG: 100.three | Normal diet; no medications or supplements that change carbohydrate or lipid metabolism; no restrictions on tea or coffee intake |
| Control tea: C: 6.i; CG: four.iv; GC: 23.8; GCG: 24.1; EC: 4.eight; ECG: 5.i; EGC: 11.2; EGCG: 16.7 | |||||||||
| Nagao et al, 2005 (19), northward = 35 | Double-blinded, parallel | Ø | Healthy men, normal to overweight | BMI: 24.9, 25.0; WT: 73.ix, 73.8; WC: 87.nine, 87.viii; WHR 2 : 0.90, 0.91 | 12 | 340 mL GTE/oolong tea beverage (690 mg catechins), 75 mg caffeine | 340 mL oolong tea drink containing 22 mg catechins, 78 mg caffeine | Enriched tea: C: 45.9; EC: 44.v; CG: 32.6; ECG: 51.three; GC: 137.4; EGC: 102.7; GCG: 139.four; EGCG: 136 | two planned meals per twenty-four hours at cafeteria; no tea or other foods loftier in catechins; <27.five mL alcohol/d |
| Control tea: C: 1.7; EC: 1; CG: 0.7; ECG: 0; GC: 5.eight; EGC: 3.7; GCG: 5.8; EGCG: iii.i | |||||||||
| Tsuchida et al, 2002 (20), north = eighty | Double-blinded, parallel | Ø | Men and postmenopausal women, BMI 24–30 | BMI: 26.4, 26.1; WT: 70.7, seventy.four; WC: 85.2, 86.2; WHR: 0.87, 0.89 | 12 | 340 mL green tea beverage (588 mg catechins), 83 mg caffeine | 340 mL light-green tea drink with 126 mg catechins, 81 mg caffeine | Enriched tea: C: 39.4; CG: 34.7; GC: 134.3; GCG: 126.5; EC: 27.five; ECG: 30.half dozen; EGC: 79.six; EGCG: 114.9 | Normal diet and exercise; no additional foods that may affect energy or metabolism; patients recorded diet and exercise 3 times/wk |
| Control tea: C: 7.8; CG: 5.8; CG: 32; GCG: 27.2; EC: iv.viii; ECG: 5.4; EGC: 18.7; EGCG: 25.2 | |||||||||
| Green tea catechins with caffeine compared with caffeine-gratuitous control | |||||||||
| Auvichayapat et al, 2008 (21), due north = 60 | Double-blinded, parallel | + | Men and postmenopausal women aged twoscore–sixty y; BMI >25 | BMI: 27.42, 28; WT: 69.3, 71.ix; WC: 88.06, 92.23; WHR: 0.86, 0.86 | 12 | 750 mg GTE capsules (141 mg catechins), 87 mg caffeine | Placebo (cellulose) capsules | EGCG: 100.7; ECG: 27.8; C: 12.3 | 8374 kcal/d of hospital-prepared meals |
| Hsu et al, 2008 (22), north = 78 | Double-blinded, parallel | + | Females aged sixteen–60 y, BMI >27 | BMI: 31.2, thirty.5; WT: 78.5, 76.3; WC: 94.seven, 93.0; WHR 2 : 0.86, 0.85 | 12 | 1200 mg GTE capsules (491 mg catechins), 27.3 mg caffeine | Placebo (cellulose) capsules | GC: 61.6; EGC: 36.9; C: 8.iii; EC: 70.3; EGCG: 377.1; GCG: 27.5; ECG: 31.8 | Maintain normal nutrition, no other antiobesity treatment |
| Chan et al, 2006 (23), n = 34 | Single-blinded, parallel | + | Women anile 25–twoscore y with PCOS; BMI >28 | BMI 3 : xxx.v, 29.seven; WT 3 :76.0, 76.6; WHR 3 : 0.85, 0.86 | 12 | Green tea capsules (661 mg catechins), 152 mg caffeine | Placebo (not specified) capsules | EGCG: 538.4; EGC: 50.vi; ECG: 38.3; EC: 32 | No boosted caffeine; nutritional consults |
| Diepvens et al, 2005 (24), north = 46 | Double-blinded, parallel | + | Women anile 19–57 y, BMI 25–31, moderate caffeine utilize | BMI: 27.7, 27.6; WT: 76.4, 76.three; WC: 85.6, 84.0; WHR: 0.81, 0.79 | 12.4 | GTE capsules (1207 mg catechins), 237 mg caffeine | Placebo (maltodextrin) capsules | EC: 126, EGC: 240.3, ECG: 212.4, EGCG: 595.8, C: 31.v | three cups coffee/d, no additional caffeine, Slim Fast (Unilever, Englewood Cliffs, NJ) diet |
| Fukino et al, 2005 (25, 36), n = 66 | Open up-label, parallel | Ø | Patients with diabetes or patients with prediabetes | BMI: 25.v, 25.9; WT: 68.2, 69.8 | 8 | GTE powder packets (456 mg catechins), 102 mg caffeine | No intervention | NR | Both groups allowed to beverage green tea every bit normal |
| Maron et al, 2003 (26), n = 240 | Double-blinded, parallel | + | Patients with balmy-to-moderate hypercholesterolemia | BMI: 24.0, 24.iv; WT 4 : 65.49, 66.09 | 12 | Theaflavin- enriched GTE (150 mg catechins), caffeine content NR | Placebo (inert ingredients) | NR | Habitual, traditional Chinese nutrition, including customary intake of tea |
| Caffeine-costless green tea catechins compared with caffeine-gratis command | |||||||||
| Takeshita et al, 2008 (27), n = 81 | Double-blinded, parallel | Ø | Healthy males, BMI ≥ 25 | BMI: 27.8, 28; WT: 82.3, 82.8; WC: 93.0, 93.9; WHR two : 0.91, 0.92 | 12 | "Sports drink" containing decaffeinated GTE (548 mg catechins) | "Sports drink" containing no catechins or caffeine | C: 17.5; EC: 50.5; CG: 0, EGC: 18.5; GC: 39.5; EGCG: 282; GCG: 132.v | Maintain habitual lifestyle; no additional tea; java limited to 200 mL/d |
| Hill et al, 2007 (28), northward = 38 | Double-blinded, parallel | + | Postmenopausal women aged 45–70 y, BMI 25–39.ix | BMI: 30.65, 31.39; WT: 79.92, 81.05; WC: 102.4, 104.vii; WHR: 0.909, 0.92 | 12 | Teavigo capsules (282 mg EGCG) | Placebo (lactose) capsules | EGCG: 282 | Maintain normal diet; run/walk 45 min iii times/wk at heart rate of 75% age-predicted maximum |
| Full sample size | Study design | ADA quality rating | Population | Baseline characteristics (I, C) | Follow-up | Tea group | Command group | Catechin components | Concurrent lifestyle modifications |
| wk | mg | ||||||||
| Dark-green tea catechins with caffeine compared with caffeine-matched control | |||||||||
| Frank et al, 2009 (14), n = 33 | Double-blinded, parallel | + | Good for you men, age 18–55 y, BMI 22–32 | BMI: 26.7, 25.4 | 3 | Aqueous GTE sheathing (714 mg catechins), 114 mg caffeine | Placebo (maltodextrin) capsules with 114 mg caffeine | EGC: 282; EGCG: 150; ECG:84; GC: 54; GCG: 48; EC: thirty; CG: xviii; C: 6 | Limit daily tea and coffee consumption to ≤3 cups (711 mL) only maintain normal nutrition and do |
| Maki et al, 2009 (15), due north = 129 | Double-blinded, parallel | + | Age 21–65 y, WC ≥90/87 (men/women), total cholesterol ≥5.2 mmol/50 | BMI: 32.2, 32.2; WT: 95.1, 95.1; WC: 108.2, 108.nine | 12 | 500 mL green tea beverage (625 mg catechins), 39 mg caffeine | Placebo drinkable containing 0 mg catechins, 39 mg caffeine, same number of calories | GC: 51.8; GC: 207.5; C: 19.2; EC: 53.ix; EGCG: 214.4; GCG: 15.4; ECG: 56.v; CG: half dozen | Limit to ≤2 caffeinated beverages per mean solar day (excluding study beverage); normal diet; ≥180 min practise weekly, including 3 supervised exercise sessions per week |
| Nagao et al, 2009 (sixteen), north = 43 | Double-blinded, parallel | + | T2DM (no insulin therapy, stable medication and diet) | BMI: 25.6, 24.0; WT: 61.8, 60.0; WC: 89.8, 86.5; WHR: 0.93, 0.91 | 12 | 340 mL dark-green tea drink (583 mg catechins), 70 mg caffeine | 340 mL green tea beverage containing 96 mg catechins and 70 mg caffeine | Enriched tea: C: 42.viii; CG: 40.ane; GC: 127.5; GCG: 139.7; EC: 32.3; ECG: 30.9; EGC: 69.four; EGCG: 100.3 | Normal diet; no catechin-rich foods that might change carbohydrate or lipid metabolism |
| Control tea: C: 6.1; CG: 4.iv; GC: 23.8; GCG: 24.one; EC: 4.8; ECG: 5.1; EGC: 11.ii; EGCG: 16.seven | |||||||||
| Matsuyama et al, 2008 (17), n = 40 | Double-blinded, parallel | + | Children aged 6–16 y, BMI >28 or diagnosis of obesity | BMI: 27.ii, 27.4; WT: 65.5, 65.4; WC: 89.ii, 88.ix; WHR: 0.95, 0.94 | 24 | 340 mL green tea beverage (576 mg catechins), 80 mg caffeine | 340 mL light-green tea potable containing 75 mg catechins, 78 mg caffeine | Enriched tea: C: 39.8; CG: 36.7; GC: 128.nine; GCG: 135.7; EC: 29.two; ECG: 32; EGC: 71.four; EGCG: 102.three | No excess lipids, sugars, or caffeine; no catechin-rich foods; no "foods that reduce excess adiposity;" maintain usual exercise |
| Control tea: C: 5.8; CG: 3.seven; GC: 20.4; GCG: 17.3; EC: 4.iv; ECG: 3.7; EGC: seven.8; EGCG: 11.six | |||||||||
| Nagao et al, 2007 (18), n = 240 | Double-blinded, parallel | + | Age 25–55 y, BMI 24–30, and/or WC eighty–94 | BMI: 26.ix, 26.7; WT: 73.iii, 72.ane; WC: 87.2, 86.5; WHR 2 : 0.89, 0.89 | 12 | 340 mL green tea beverage (583 mg catechins), 70 mg caffeine | 340 mL green tea drink containing 96 mg catechins and lxx mg caffeine | Enriched tea: C: 42.viii; CG: 40.one; GC: 127.5; GCG: 139.vii; EC: 32.3; ECG: xxx.9; EGC: 69.4; EGCG: 100.iii | Normal diet; no medications or supplements that change carbohydrate or lipid metabolism; no restrictions on tea or coffee intake |
| Control tea: C: vi.i; CG: iv.4; GC: 23.8; GCG: 24.ane; EC: four.8; ECG: v.1; EGC: 11.two; EGCG: 16.7 | |||||||||
| Nagao et al, 2005 (xix), n = 35 | Double-blinded, parallel | Ø | Salubrious men, normal to overweight | BMI: 24.9, 25.0; WT: 73.9, 73.eight; WC: 87.9, 87.eight; WHR 2 : 0.90, 0.91 | 12 | 340 mL GTE/oolong tea potable (690 mg catechins), 75 mg caffeine | 340 mL oolong tea drinkable containing 22 mg catechins, 78 mg caffeine | Enriched tea: C: 45.ix; EC: 44.v; CG: 32.6; ECG: 51.3; GC: 137.4; EGC: 102.7; GCG: 139.4; EGCG: 136 | ii planned meals per day at cafeteria; no tea or other foods loftier in catechins; <27.5 mL booze/d |
| Control tea: C: 1.7; EC: 1; CG: 0.7; ECG: 0; GC: 5.8; EGC: 3.7; GCG: 5.8; EGCG: three.1 | |||||||||
| Tsuchida et al, 2002 (20), n = 80 | Double-blinded, parallel | Ø | Men and postmenopausal women, BMI 24–30 | BMI: 26.4, 26.one; WT: lxx.seven, seventy.4; WC: 85.2, 86.two; WHR: 0.87, 0.89 | 12 | 340 mL green tea beverage (588 mg catechins), 83 mg caffeine | 340 mL green tea beverage with 126 mg catechins, 81 mg caffeine | Enriched tea: C: 39.iv; CG: 34.seven; GC: 134.3; GCG: 126.5; EC: 27.5; ECG: 30.6; EGC: 79.6; EGCG: 114.9 | Normal diet and exercise; no additional foods that may affect energy or metabolism; patients recorded diet and exercise 3 times/wk |
| Control tea: C: 7.8; CG: 5.8; CG: 32; GCG: 27.ii; EC: four.8; ECG: 5.4; EGC: eighteen.vii; EGCG: 25.2 | |||||||||
| Green tea catechins with caffeine compared with caffeine-free control | |||||||||
| Auvichayapat et al, 2008 (21), northward = sixty | Double-blinded, parallel | + | Men and postmenopausal women aged 40–sixty y; BMI >25 | BMI: 27.42, 28; WT: 69.3, 71.9; WC: 88.06, 92.23; WHR: 0.86, 0.86 | 12 | 750 mg GTE capsules (141 mg catechins), 87 mg caffeine | Placebo (cellulose) capsules | EGCG: 100.7; ECG: 27.viii; C: 12.three | 8374 kcal/d of hospital-prepared meals |
| Hsu et al, 2008 (22), northward = 78 | Double-blinded, parallel | + | Females anile xvi–60 y, BMI >27 | BMI: 31.2, 30.5; WT: 78.5, 76.three; WC: 94.vii, 93.0; WHR 2 : 0.86, 0.85 | 12 | 1200 mg GTE capsules (491 mg catechins), 27.3 mg caffeine | Placebo (cellulose) capsules | GC: 61.6; EGC: 36.ix; C: 8.three; EC: lxx.3; EGCG: 377.i; GCG: 27.5; ECG: 31.eight | Maintain normal diet, no other antiobesity treatment |
| Chan et al, 2006 (23), north = 34 | Unmarried-blinded, parallel | + | Women aged 25–40 y with PCOS; BMI >28 | BMI 3 : 30.v, 29.vii; WT 3 :76.0, 76.six; WHR three : 0.85, 0.86 | 12 | Green tea capsules (661 mg catechins), 152 mg caffeine | Placebo (non specified) capsules | EGCG: 538.4; EGC: 50.6; ECG: 38.3; EC: 32 | No boosted caffeine; nutritional consults |
| Diepvens et al, 2005 (24), due north = 46 | Double-blinded, parallel | + | Women aged xix–57 y, BMI 25–31, moderate caffeine utilise | BMI: 27.7, 27.6; WT: 76.4, 76.3; WC: 85.half-dozen, 84.0; WHR: 0.81, 0.79 | 12.4 | GTE capsules (1207 mg catechins), 237 mg caffeine | Placebo (maltodextrin) capsules | EC: 126, EGC: 240.iii, ECG: 212.4, EGCG: 595.eight, C: 31.5 | iii cups coffee/d, no additional caffeine, Slim Fast (Unilever, Englewood Cliffs, NJ) nutrition |
| Fukino et al, 2005 (25, 36), n = 66 | Open up-label, parallel | Ø | Patients with diabetes or patients with prediabetes | BMI: 25.5, 25.9; WT: 68.2, 69.eight | eight | GTE pulverization packets (456 mg catechins), 102 mg caffeine | No intervention | NR | Both groups allowed to drink green tea as normal |
| Maron et al, 2003 (26), north = 240 | Double-blinded, parallel | + | Patients with mild-to-moderate hypercholesterolemia | BMI: 24.0, 24.4; WT four : 65.49, 66.09 | 12 | Theaflavin- enriched GTE (150 mg catechins), caffeine content NR | Placebo (inert ingredients) | NR | Habitual, traditional Chinese diet, including customary intake of tea |
| Caffeine-free green tea catechins compared with caffeine-free control | |||||||||
| Takeshita et al, 2008 (27), n = 81 | Double-blinded, parallel | Ø | Healthy males, BMI ≥ 25 | BMI: 27.8, 28; WT: 82.3, 82.viii; WC: 93.0, 93.nine; WHR 2 : 0.91, 0.92 | 12 | "Sports drinkable" containing decaffeinated GTE (548 mg catechins) | "Sports drink" containing no catechins or caffeine | C: 17.5; EC: fifty.v; CG: 0, EGC: xviii.5; GC: 39.v; EGCG: 282; GCG: 132.v | Maintain habitual lifestyle; no additional tea; coffee express to 200 mL/d |
| Hill et al, 2007 (28), north = 38 | Double-blinded, parallel | + | Postmenopausal women aged 45–70 y, BMI 25–39.9 | BMI: 30.65, 31.39; WT: 79.92, 81.05; WC: 102.4, 104.vii; WHR: 0.909, 0.92 | 12 | Teavigo capsules (282 mg EGCG) | Placebo (lactose) capsules | EGCG: 282 | Maintain normal nutrition; run/walk 45 min 3 times/wk at heart charge per unit of 75% age-predicted maximum |
i BMIs are provided in kg/ktwo. ADA, American Dietetic Association; ø, neutral; +, positive; I, intervention; C, control; WT, weight (kg); WC, waist circumference (cm); WHR, waist-to-hip ratio; GTE, green tea extract; EGCG, epigallocatechin gallate; ECG, epicatechin gallate; EGC, epigallocatechin; EC, epicatechin; GC, gallocatechin; CG, catechin gallate; GCG, gallocatechin gallate; C, catechin; PCOS, polycystic ovarian syndrome; T2DM, blazon 2 diabetes mellitus; NR, not reported.
ii WHR not provided in the publication; value calculated from baseline WC and hip circumference.
3 Median value.
four Unpublished data obtained from personal communication with the author (D Maron, 2009).
Table i
Characteristics of included randomized controlled trials of green tea catechins one
| Full sample size | Study design | ADA quality rating | Population | Baseline characteristics (I, C) | Follow-up | Tea group | Control group | Catechin components | Concurrent lifestyle modifications |
| wk | mg | ||||||||
| Green tea catechins with caffeine compared with caffeine-matched control | |||||||||
| Frank et al, 2009 (fourteen), north = 33 | Double-blinded, parallel | + | Good for you men, age 18–55 y, BMI 22–32 | BMI: 26.7, 25.4 | 3 | Aqueous GTE capsule (714 mg catechins), 114 mg caffeine | Placebo (maltodextrin) capsules with 114 mg caffeine | EGC: 282; EGCG: 150; ECG:84; GC: 54; GCG: 48; EC: 30; CG: 18; C: 6 | Limit daily tea and coffee consumption to ≤three cups (711 mL) but maintain normal diet and exercise |
| Maki et al, 2009 (xv), n = 129 | Double-blinded, parallel | + | Historic period 21–65 y, WC ≥ninety/87 (men/women), total cholesterol ≥v.two mmol/L | BMI: 32.2, 32.2; WT: 95.1, 95.1; WC: 108.2, 108.9 | 12 | 500 mL green tea beverage (625 mg catechins), 39 mg caffeine | Placebo potable containing 0 mg catechins, 39 mg caffeine, same number of calories | GC: 51.8; GC: 207.5; C: xix.2; EC: 53.9; EGCG: 214.iv; GCG: 15.iv; ECG: 56.5; CG: 6 | Limit to ≤2 caffeinated beverages per day (excluding study beverage); normal diet; ≥180 min practice weekly, including three supervised do sessions per week |
| Nagao et al, 2009 (16), n = 43 | Double-blinded, parallel | + | T2DM (no insulin therapy, stable medication and diet) | BMI: 25.six, 24.0; WT: 61.eight, threescore.0; WC: 89.8, 86.5; WHR: 0.93, 0.91 | 12 | 340 mL green tea beverage (583 mg catechins), 70 mg caffeine | 340 mL green tea drinkable containing 96 mg catechins and lxx mg caffeine | Enriched tea: C: 42.8; CG: forty.1; GC: 127.5; GCG: 139.7; EC: 32.3; ECG: xxx.ix; EGC: 69.4; EGCG: 100.3 | Normal diet; no catechin-rich foods that might modify saccharide or lipid metabolism |
| Control tea: C: 6.1; CG: 4.4; GC: 23.viii; GCG: 24.1; EC: 4.8; ECG: 5.one; EGC: 11.2; EGCG: sixteen.7 | |||||||||
| Matsuyama et al, 2008 (17), n = 40 | Double-blinded, parallel | + | Children aged six–16 y, BMI >28 or diagnosis of obesity | BMI: 27.2, 27.4; WT: 65.5, 65.4; WC: 89.2, 88.9; WHR: 0.95, 0.94 | 24 | 340 mL green tea beverage (576 mg catechins), eighty mg caffeine | 340 mL green tea potable containing 75 mg catechins, 78 mg caffeine | Enriched tea: C: 39.8; CG: 36.seven; GC: 128.9; GCG: 135.7; EC: 29.2; ECG: 32; EGC: 71.4; EGCG: 102.three | No excess lipids, sugars, or caffeine; no catechin-rich foods; no "foods that reduce excess adiposity;" maintain usual exercise |
| Control tea: C: 5.8; CG: 3.seven; GC: 20.4; GCG: 17.3; EC: iv.4; ECG: 3.7; EGC: vii.8; EGCG: 11.6 | |||||||||
| Nagao et al, 2007 (18), due north = 240 | Double-blinded, parallel | + | Historic period 25–55 y, BMI 24–30, and/or WC fourscore–94 | BMI: 26.nine, 26.7; WT: 73.three, 72.ane; WC: 87.2, 86.5; WHR 2 : 0.89, 0.89 | 12 | 340 mL green tea beverage (583 mg catechins), 70 mg caffeine | 340 mL green tea drinkable containing 96 mg catechins and 70 mg caffeine | Enriched tea: C: 42.eight; CG: twoscore.1; GC: 127.5; GCG: 139.7; EC: 32.3; ECG: 30.9; EGC: 69.4; EGCG: 100.three | Normal nutrition; no medications or supplements that change sugar or lipid metabolism; no restrictions on tea or coffee intake |
| Control tea: C: 6.1; CG: four.iv; GC: 23.viii; GCG: 24.ane; EC: iv.eight; ECG: 5.1; EGC: 11.ii; EGCG: sixteen.seven | |||||||||
| Nagao et al, 2005 (nineteen), northward = 35 | Double-blinded, parallel | Ø | Healthy men, normal to overweight | BMI: 24.9, 25.0; WT: 73.9, 73.viii; WC: 87.9, 87.eight; WHR 2 : 0.90, 0.91 | 12 | 340 mL GTE/oolong tea beverage (690 mg catechins), 75 mg caffeine | 340 mL oolong tea beverage containing 22 mg catechins, 78 mg caffeine | Enriched tea: C: 45.9; EC: 44.5; CG: 32.half-dozen; ECG: 51.three; GC: 137.four; EGC: 102.7; GCG: 139.4; EGCG: 136 | 2 planned meals per day at cafeteria; no tea or other foods loftier in catechins; <27.5 mL alcohol/d |
| Control tea: C: 1.seven; EC: 1; CG: 0.vii; ECG: 0; GC: 5.eight; EGC: 3.7; GCG: 5.eight; EGCG: three.ane | |||||||||
| Tsuchida et al, 2002 (20), n = 80 | Double-blinded, parallel | Ø | Men and postmenopausal women, BMI 24–30 | BMI: 26.4, 26.ane; WT: lxx.7, 70.4; WC: 85.2, 86.2; WHR: 0.87, 0.89 | 12 | 340 mL greenish tea beverage (588 mg catechins), 83 mg caffeine | 340 mL greenish tea potable with 126 mg catechins, 81 mg caffeine | Enriched tea: C: 39.four; CG: 34.7; GC: 134.3; GCG: 126.5; EC: 27.v; ECG: thirty.6; EGC: 79.half-dozen; EGCG: 114.9 | Normal diet and exercise; no additional foods that may affect energy or metabolism; patients recorded diet and do 3 times/wk |
| Command tea: C: vii.8; CG: 5.8; CG: 32; GCG: 27.ii; EC: 4.8; ECG: 5.iv; EGC: 18.7; EGCG: 25.two | |||||||||
| Green tea catechins with caffeine compared with caffeine-free command | |||||||||
| Auvichayapat et al, 2008 (21), n = sixty | Double-blinded, parallel | + | Men and postmenopausal women anile 40–60 y; BMI >25 | BMI: 27.42, 28; WT: 69.three, 71.nine; WC: 88.06, 92.23; WHR: 0.86, 0.86 | 12 | 750 mg GTE capsules (141 mg catechins), 87 mg caffeine | Placebo (cellulose) capsules | EGCG: 100.vii; ECG: 27.8; C: 12.3 | 8374 kcal/d of infirmary-prepared meals |
| Hsu et al, 2008 (22), n = 78 | Double-blinded, parallel | + | Females aged 16–60 y, BMI >27 | BMI: 31.2, 30.5; WT: 78.5, 76.three; WC: 94.7, 93.0; WHR 2 : 0.86, 0.85 | 12 | 1200 mg GTE capsules (491 mg catechins), 27.iii mg caffeine | Placebo (cellulose) capsules | GC: 61.6; EGC: 36.9; C: viii.3; EC: 70.iii; EGCG: 377.i; GCG: 27.five; ECG: 31.8 | Maintain normal diet, no other antiobesity treatment |
| Chan et al, 2006 (23), northward = 34 | Unmarried-blinded, parallel | + | Women anile 25–40 y with PCOS; BMI >28 | BMI 3 : 30.5, 29.7; WT 3 :76.0, 76.half-dozen; WHR 3 : 0.85, 0.86 | 12 | Light-green tea capsules (661 mg catechins), 152 mg caffeine | Placebo (not specified) capsules | EGCG: 538.4; EGC: fifty.6; ECG: 38.3; EC: 32 | No boosted caffeine; nutritional consults |
| Diepvens et al, 2005 (24), n = 46 | Double-blinded, parallel | + | Women aged nineteen–57 y, BMI 25–31, moderate caffeine employ | BMI: 27.7, 27.6; WT: 76.iv, 76.three; WC: 85.6, 84.0; WHR: 0.81, 0.79 | 12.4 | GTE capsules (1207 mg catechins), 237 mg caffeine | Placebo (maltodextrin) capsules | EC: 126, EGC: 240.3, ECG: 212.four, EGCG: 595.8, C: 31.5 | 3 cups coffee/d, no additional caffeine, Slim Fast (Unilever, Englewood Cliffs, NJ) diet |
| Fukino et al, 2005 (25, 36), n = 66 | Open up-label, parallel | Ø | Patients with diabetes or patients with prediabetes | BMI: 25.five, 25.9; WT: 68.2, 69.8 | 8 | GTE powder packets (456 mg catechins), 102 mg caffeine | No intervention | NR | Both groups allowed to drinkable green tea as normal |
| Maron et al, 2003 (26), n = 240 | Double-blinded, parallel | + | Patients with mild-to-moderate hypercholesterolemia | BMI: 24.0, 24.4; WT iv : 65.49, 66.09 | 12 | Theaflavin- enriched GTE (150 mg catechins), caffeine content NR | Placebo (inert ingredients) | NR | Habitual, traditional Chinese diet, including customary intake of tea |
| Caffeine-free dark-green tea catechins compared with caffeine-costless control | |||||||||
| Takeshita et al, 2008 (27), n = 81 | Double-blinded, parallel | Ø | Good for you males, BMI ≥ 25 | BMI: 27.eight, 28; WT: 82.3, 82.8; WC: 93.0, 93.nine; WHR 2 : 0.91, 0.92 | 12 | "Sports drink" containing decaffeinated GTE (548 mg catechins) | "Sports potable" containing no catechins or caffeine | C: 17.five; EC: 50.5; CG: 0, EGC: 18.5; GC: 39.v; EGCG: 282; GCG: 132.v | Maintain habitual lifestyle; no additional tea; coffee limited to 200 mL/d |
| Hill et al, 2007 (28), due north = 38 | Double-blinded, parallel | + | Postmenopausal women anile 45–70 y, BMI 25–39.ix | BMI: 30.65, 31.39; WT: 79.92, 81.05; WC: 102.4, 104.vii; WHR: 0.909, 0.92 | 12 | Teavigo capsules (282 mg EGCG) | Placebo (lactose) capsules | EGCG: 282 | Maintain normal diet; run/walk 45 min 3 times/wk at heart charge per unit of 75% historic period-predicted maximum |
| Full sample size | Study design | ADA quality rating | Population | Baseline characteristics (I, C) | Follow-up | Tea grouping | Control group | Catechin components | Concurrent lifestyle modifications |
| wk | mg | ||||||||
| Green tea catechins with caffeine compared with caffeine-matched control | |||||||||
| Frank et al, 2009 (14), n = 33 | Double-blinded, parallel | + | Healthy men, age eighteen–55 y, BMI 22–32 | BMI: 26.seven, 25.4 | 3 | Aqueous GTE capsule (714 mg catechins), 114 mg caffeine | Placebo (maltodextrin) capsules with 114 mg caffeine | EGC: 282; EGCG: 150; ECG:84; GC: 54; GCG: 48; EC: 30; CG: 18; C: 6 | Limit daily tea and coffee consumption to ≤3 cups (711 mL) but maintain normal nutrition and practice |
| Maki et al, 2009 (15), n = 129 | Double-blinded, parallel | + | Age 21–65 y, WC ≥90/87 (men/women), full cholesterol ≥5.2 mmol/L | BMI: 32.2, 32.2; WT: 95.ane, 95.1; WC: 108.2, 108.9 | 12 | 500 mL green tea beverage (625 mg catechins), 39 mg caffeine | Placebo beverage containing 0 mg catechins, 39 mg caffeine, same number of calories | GC: 51.8; GC: 207.5; C: nineteen.two; EC: 53.9; EGCG: 214.4; GCG: fifteen.4; ECG: 56.5; CG: 6 | Limit to ≤two caffeinated beverages per day (excluding study drink); normal nutrition; ≥180 min practice weekly, including 3 supervised exercise sessions per calendar week |
| Nagao et al, 2009 (16), north = 43 | Double-blinded, parallel | + | T2DM (no insulin therapy, stable medication and diet) | BMI: 25.6, 24.0; WT: 61.8, 60.0; WC: 89.8, 86.v; WHR: 0.93, 0.91 | 12 | 340 mL dark-green tea beverage (583 mg catechins), 70 mg caffeine | 340 mL green tea potable containing 96 mg catechins and 70 mg caffeine | Enriched tea: C: 42.viii; CG: twoscore.i; GC: 127.5; GCG: 139.7; EC: 32.3; ECG: 30.ix; EGC: 69.iv; EGCG: 100.3 | Normal nutrition; no catechin-rich foods that might change carbohydrate or lipid metabolism |
| Control tea: C: 6.i; CG: 4.4; GC: 23.viii; GCG: 24.i; EC: 4.eight; ECG: 5.ane; EGC: eleven.2; EGCG: 16.vii | |||||||||
| Matsuyama et al, 2008 (17), north = twoscore | Double-blinded, parallel | + | Children aged 6–16 y, BMI >28 or diagnosis of obesity | BMI: 27.2, 27.four; WT: 65.5, 65.4; WC: 89.2, 88.9; WHR: 0.95, 0.94 | 24 | 340 mL light-green tea beverage (576 mg catechins), 80 mg caffeine | 340 mL green tea beverage containing 75 mg catechins, 78 mg caffeine | Enriched tea: C: 39.eight; CG: 36.7; GC: 128.9; GCG: 135.7; EC: 29.two; ECG: 32; EGC: 71.4; EGCG: 102.3 | No excess lipids, sugars, or caffeine; no catechin-rich foods; no "foods that reduce excess adiposity;" maintain usual exercise |
| Command tea: C: 5.8; CG: 3.7; GC: 20.iv; GCG: 17.three; EC: 4.4; ECG: 3.7; EGC: 7.8; EGCG: xi.half-dozen | |||||||||
| Nagao et al, 2007 (eighteen), n = 240 | Double-blinded, parallel | + | Age 25–55 y, BMI 24–30, and/or WC 80–94 | BMI: 26.9, 26.7; WT: 73.three, 72.ane; WC: 87.2, 86.5; WHR 2 : 0.89, 0.89 | 12 | 340 mL green tea potable (583 mg catechins), 70 mg caffeine | 340 mL green tea drink containing 96 mg catechins and 70 mg caffeine | Enriched tea: C: 42.8; CG: 40.i; GC: 127.5; GCG: 139.7; EC: 32.iii; ECG: 30.9; EGC: 69.iv; EGCG: 100.3 | Normal diet; no medications or supplements that change sugar or lipid metabolism; no restrictions on tea or java intake |
| Command tea: C: 6.1; CG: 4.4; GC: 23.8; GCG: 24.1; EC: 4.eight; ECG: v.1; EGC: 11.2; EGCG: xvi.7 | |||||||||
| Nagao et al, 2005 (19), n = 35 | Double-blinded, parallel | Ø | Healthy men, normal to overweight | BMI: 24.9, 25.0; WT: 73.9, 73.8; WC: 87.9, 87.8; WHR 2 : 0.90, 0.91 | 12 | 340 mL GTE/oolong tea beverage (690 mg catechins), 75 mg caffeine | 340 mL oolong tea beverage containing 22 mg catechins, 78 mg caffeine | Enriched tea: C: 45.nine; EC: 44.5; CG: 32.6; ECG: 51.three; GC: 137.four; EGC: 102.seven; GCG: 139.four; EGCG: 136 | 2 planned meals per day at cafeteria; no tea or other foods high in catechins; <27.5 mL alcohol/d |
| Control tea: C: i.7; EC: 1; CG: 0.7; ECG: 0; GC: 5.8; EGC: 3.seven; GCG: five.eight; EGCG: 3.1 | |||||||||
| Tsuchida et al, 2002 (20), n = lxxx | Double-blinded, parallel | Ø | Men and postmenopausal women, BMI 24–xxx | BMI: 26.four, 26.1; WT: lxx.vii, 70.4; WC: 85.two, 86.2; WHR: 0.87, 0.89 | 12 | 340 mL dark-green tea beverage (588 mg catechins), 83 mg caffeine | 340 mL green tea beverage with 126 mg catechins, 81 mg caffeine | Enriched tea: C: 39.iv; CG: 34.seven; GC: 134.3; GCG: 126.5; EC: 27.5; ECG: 30.half-dozen; EGC: 79.6; EGCG: 114.9 | Normal diet and practise; no additional foods that may bear upon energy or metabolism; patients recorded nutrition and practise three times/wk |
| Command tea: C: vii.eight; CG: 5.8; CG: 32; GCG: 27.2; EC: 4.8; ECG: 5.4; EGC: xviii.vii; EGCG: 25.2 | |||||||||
| Light-green tea catechins with caffeine compared with caffeine-free control | |||||||||
| Auvichayapat et al, 2008 (21), n = 60 | Double-blinded, parallel | + | Men and postmenopausal women aged 40–60 y; BMI >25 | BMI: 27.42, 28; WT: 69.3, 71.9; WC: 88.06, 92.23; WHR: 0.86, 0.86 | 12 | 750 mg GTE capsules (141 mg catechins), 87 mg caffeine | Placebo (cellulose) capsules | EGCG: 100.seven; ECG: 27.8; C: 12.3 | 8374 kcal/d of hospital-prepared meals |
| Hsu et al, 2008 (22), northward = 78 | Double-blinded, parallel | + | Females aged 16–threescore y, BMI >27 | BMI: 31.2, 30.v; WT: 78.5, 76.3; WC: 94.7, 93.0; WHR ii : 0.86, 0.85 | 12 | 1200 mg GTE capsules (491 mg catechins), 27.three mg caffeine | Placebo (cellulose) capsules | GC: 61.6; EGC: 36.nine; C: 8.3; EC: lxx.three; EGCG: 377.1; GCG: 27.5; ECG: 31.8 | Maintain normal diet, no other antiobesity treatment |
| Chan et al, 2006 (23), north = 34 | Single-blinded, parallel | + | Women anile 25–twoscore y with PCOS; BMI >28 | BMI 3 : 30.5, 29.7; WT 3 :76.0, 76.six; WHR 3 : 0.85, 0.86 | 12 | Green tea capsules (661 mg catechins), 152 mg caffeine | Placebo (not specified) capsules | EGCG: 538.four; EGC: 50.half-dozen; ECG: 38.3; EC: 32 | No additional caffeine; nutritional consults |
| Diepvens et al, 2005 (24), n = 46 | Double-blinded, parallel | + | Women aged 19–57 y, BMI 25–31, moderate caffeine utilise | BMI: 27.vii, 27.half dozen; WT: 76.four, 76.3; WC: 85.6, 84.0; WHR: 0.81, 0.79 | 12.iv | GTE capsules (1207 mg catechins), 237 mg caffeine | Placebo (maltodextrin) capsules | EC: 126, EGC: 240.3, ECG: 212.4, EGCG: 595.8, C: 31.5 | 3 cups coffee/d, no additional caffeine, Slim Fast (Unilever, Englewood Cliffs, NJ) diet |
| Fukino et al, 2005 (25, 36), n = 66 | Open-label, parallel | Ø | Patients with diabetes or patients with prediabetes | BMI: 25.5, 25.ix; WT: 68.2, 69.8 | viii | GTE powder packets (456 mg catechins), 102 mg caffeine | No intervention | NR | Both groups allowed to drink light-green tea as normal |
| Maron et al, 2003 (26), n = 240 | Double-blinded, parallel | + | Patients with mild-to-moderate hypercholesterolemia | BMI: 24.0, 24.iv; WT 4 : 65.49, 66.09 | 12 | Theaflavin- enriched GTE (150 mg catechins), caffeine content NR | Placebo (inert ingredients) | NR | Habitual, traditional Chinese nutrition, including customary intake of tea |
| Caffeine-free greenish tea catechins compared with caffeine-free control | |||||||||
| Takeshita et al, 2008 (27), n = 81 | Double-blinded, parallel | Ø | Salubrious males, BMI ≥ 25 | BMI: 27.8, 28; WT: 82.3, 82.eight; WC: 93.0, 93.ix; WHR 2 : 0.91, 0.92 | 12 | "Sports drink" containing decaffeinated GTE (548 mg catechins) | "Sports drink" containing no catechins or caffeine | C: 17.five; EC: l.five; CG: 0, EGC: 18.5; GC: 39.v; EGCG: 282; GCG: 132.five | Maintain habitual lifestyle; no additional tea; java express to 200 mL/d |
| Hill et al, 2007 (28), n = 38 | Double-blinded, parallel | + | Postmenopausal women aged 45–70 y, BMI 25–39.9 | BMI: 30.65, 31.39; WT: 79.92, 81.05; WC: 102.4, 104.7; WHR: 0.909, 0.92 | 12 | Teavigo capsules (282 mg EGCG) | Placebo (lactose) capsules | EGCG: 282 | Maintain normal nutrition; run/walk 45 min 3 times/wk at heart rate of 75% age-predicted maximum |
1 BMIs are provided in kg/yard2. ADA, American Dietetic Clan; ø, neutral; +, positive; I, intervention; C, control; WT, weight (kg); WC, waist circumference (cm); WHR, waist-to-hip ratio; GTE, green tea extract; EGCG, epigallocatechin gallate; ECG, epicatechin gallate; EGC, epigallocatechin; EC, epicatechin; GC, gallocatechin; CG, catechin gallate; GCG, gallocatechin gallate; C, catechin; PCOS, polycystic ovarian syndrome; T2DM, blazon 2 diabetes mellitus; NR, not reported.
2 WHR not provided in the publication; value calculated from baseline WC and hip circumference.
3 Median value.
4 Unpublished information obtained from personal communication with the author (D Maron, 2009).
Quantitative data synthesis
On meta-assay of studies evaluating GTCs with caffeine compared with a caffeine-matched command, the GTC group showed statistically significant reductions in BMI, torso weight, and WC, with no statistically significant issue on WHR (Figure 2). Statistical heterogeneity was non institute for BMI or body weight (I 2 = 0% for both), just a moderate degree of heterogeneity was present for WC (I 2 = 52%) and WHR (I 2 = 27%) analyses. Review of funnel plots and the Egger'due south weighted regression statistic P value suggested potential publication bias for BMI and trunk weight (P < 0.06) but a depression likelihood for WC and WHR (P > 0.55). Trim-and-fill analyses for both BMI and trunk weight imputed iv trials, with a upshot of −0.58 (95% CI: −0.69, −0.46) and −1.54 kg (95% CI: −1.83, −i.26), respectively (Effigy three).
FIGURE ii
Woods plots depicting the upshot of green tea on BMI (A), weight (B), waist circumference (C), and waist-to-hip ratio (D). The squares correspond individual studies, and the size of the squares represents the weight given to each study in the meta-assay. Error bars represent 95% CIs. The diamonds represent the pooled results. The solid vertical line extending up from 0 is the aught value.
FIGURE ii
Forest plots depicting the effect of light-green tea on BMI (A), weight (B), waist circumference (C), and waist-to-hip ratio (D). The squares represent individual studies, and the size of the squares represents the weight given to each study in the meta-analysis. Error bars stand for 95% CIs. The diamonds stand for the pooled results. The solid vertical line extending up from 0 is the null value.
FIGURE 3
Trim-and-fill up funnel plot. The solid circles represent bodily identified studies, and the open up circles represent imputed studies from a trim-and-fill analysis. The solid vertical lines represent the effect of light-green tea catechins on BMI (A) and body weight (B) in the initial analysis, whereas the dotted vertical lines stand for the effect when allowing for publication bias.
FIGURE iii
Trim-and-make full funnel plot. The solid circles represent actual identified studies, and the open circles represent imputed studies from a trim-and-fill up analysis. The solid vertical lines stand for the effect of green tea catechins on BMI (A) and body weight (B) in the initial assay, whereas the dotted vertical lines represent the effect when assuasive for publication bias.
For the analysis of studies evaluating GTCs with caffeine compared with a caffeine-gratuitous control, the GTC grouping showed statistically significant reductions in trunk weight, simply no event on BMI, WC, or WHR was observed. Statistical heterogeneity was not detected for any of the endpoints (I two = 0% for all). There was a low potential for presence of publication bias for all endpoints, every bit assessed by funnel plots and Egger'southward weighted regression statistic P value (P > 0.68).
Meta-analysis of studies evaluating GTC without caffeine compared with a caffeine-gratis control showed no statistical significance in any of the endpoints. Because of the small number of studies in this analysis, statistical heterogeneity and publication bias were not formally assessed.
Give-and-take
Epidemiologic evidence has shown that habitual tea consumption of an average 434 mL/d for x y is associated with a lower percentage body fat and WC than no tea drinking (40). Of the tea drinkers, most (>ninety%) drank green tea, initially suggesting that GTCs take a role in weight loss (twoscore). Weight reduction due to GTCs may issue from increased energy expenditure and fatty oxidation. In healthy men supplemented with dark-green tea extract containing 270 mg EGCG and 150 mg caffeine, energy expenditure increased significantly past 4% compared with caffeine alone, and fat oxidation was 41% for dark-green tea compared with 33% for caffeine alone (P < 0.01 for both) (eight).
BMI, trunk weight, WC, and WHR were chosen for this analysis because they are considered important diagnostic indicators for overweight and obesity as well as independent risk factors for cardiovascular affliction and diabetes (1). Statistical pooling of data from the 7 trials in the analysis of GTCs with caffeine compared with a caffeine-matched command showed that ingesting GTCs at a dose ranging from 583 to 714 mg/d over a median of 12 wk had a statistically significant benefit on BMI, body weight, and WC, with no consequence on WHR. On pooling the 6 trials in the analysis of GTCs with caffeine compared with caffeine-free control, GTC ingestion significantly reduced body weight, with no upshot on BMI, WC, or WHR. Of the 2 caffeine-free trials, pooling the 2 trials showed no statistically significant result.
The inclusion of sure study characteristics of the trials in the analysis may have contributed to clinical and statistical heterogeneity and was a limitation of this meta-assay. The populations studied varied between children, healthy adults, and adults with comorbidities such as overweight or obesity, hyperlipidemia, or diabetes mellitus. Unfortunately, the broad variety of populations studied made it difficult to determine the population that would most benefit from GTCs. The wide range of GTC doses evaluated may also have contributed to the heterogeneous results; however, a previous trial showed no relation between dose and BMI (P = 0.89) (25). Because of the small number of studies in each analysis, we could non assess a dose-response relation through meta-regression. In add-on, GTC absorption increased in the fasted state (41), so variations in GTC ingestion between the trials with relation to food may besides have contributed to the heterogeneous results. In our meta-analysis, some trials stated that GTCs could exist consumed at whatever time of the 24-hour interval (15, 17, 18), whereas others specified either earlier (fourteen, 28), during (19, 24), or after (21, 22) meals. Another consideration was the variation in catechin composition amidst the trials. Although nosotros were unable to assess the event of catechin limerick on anthropometric outcomes, much of GTCs' benefits have been attributed to EGCG specifically (vii, x). Interestingly, the trial that evaluated EGCG lonely (28) showed nonsignificant increases in BMI and body weight when compared with placebo. This suggests that the consequence of GTCs might be due to the combination, rather than to any single catechin, and merits farther investigation. The presence or absence of blinding, as well as the overall quality rating of trials, may have also contributed to the heterogeneity of the results. Yet, the effects of these characteristics were not quantified via sensitivity analyses because of the express number of trials bachelor.
Considering of the abovementioned heterogeneous nature of the included trials, nosotros felt information technology inappropriate to pool all of the studies into ane unmarried analysis; therefore, the trials were analyzed as iii separate pools of information, and we recommend that our results be interpreted every bit such. Although information technology may be tempting to cross compare the results of the 3 carve up analyses, this comparing is inherently flawed. Such indirect comparisons of separate sets of trials composed of dissimilar populations provide weak evidence for concluding that any of the handling regimens have greater benefit than another.
Our meta-analysis did not pool rubber information because it was not reported in a standard manner; however, the trials reported that patients did non feel whatever major agin events (16, 18, 22, 23). Example reports of GTC consumption have brought up concerns of hepatotoxicity, and the The states Pharmacopoeia Dietary Supplements Information Expert Committee has proposed that all green tea excerpt products bear a label that suggests consumption together with food because of the possibility of severe liver problems (42). Of the trials that evaluated liver transaminases (xiv–16, 26, 28), only one reported elevations in the GTC grouping (16); still, transaminase concentrations were elevated at baseline, which suggests potential bias in grouping allocation. To assess concerns of liver damage, a randomized controlled trial using high-dose GTCs (714 mg/d) was undertaken in good for you men (fourteen). This trial found that over three wk of GTC intake, there were no elevations in liver transaminases or reports of liver dysfunction (14).
As with all meta-analyses, publication bias is a business organisation. For almost endpoints evaluated, there was a depression likelihood of publication bias, as assessed by funnel plot inspection and Egger'southward weighted regression P value. In the ii cases in which at that place was a significant presence of publication bias, trim-and-fill analyses did not significantly alter the results, which suggests that publication bias did not significantly affect our results.
Despite the statistical significance achieved in some of the analyses, the changes observed are not likely clinically relevant. For example, for pharmacologic weight-loss products on the market, patients are considered to have failed treatment if they have not accomplished a loss of ii kg after iv wk of therapy (1). In our meta-analysis, GTCs with caffeine just provided an average weight loss of >1 kg compared with a caffeine-matched control, and <0.5 kg compared with a caffeine-free command taken over a median of 12 wk. Furthermore, the observed reductions in WC, although statistically significant in some cases, were smaller than potential variations in measurement. Anthropometric measurements of WC fabricated by trained professionals can vary by one.5 to ii.1 cm between measurements (43). Therefore, reductions in WC of <2 cm cannot exist ruled out to chance and should be interpreted with circumspection.
Future studies should exist conducted to further sympathise the relation betwixt GTC intake and changes in anthropometric measures, particularly with regard to caffeine intake. In improver, future studies may exist able to identify the target population for catechin use and determine the ideal dose.
In decision, on the ground of the currently available literature, ingestion of GTCs with caffeine may positively affect BMI, body weight, and WC. However, the magnitude of effect over a median of 12 wk is small and not likely clinically relevant. Current data from a modest number of studies practise not advise that GTCs lonely positively modify anthropometric measurements.
Nosotros acknowledge David J Maron for providing unpublished data from his trial, Jeffrey Mather for his statistical review of the manuscript, and David and Chizue Thorne for their assistance with translating the Japanese articles.
The authors' responsibilities were as follows—OJP and CIC: formulated the enquiry question, conducted the literature search, analyzed the data, interpreted the data and results, and wrote the manuscript; WLB: interpreted the data and results and wrote the manuscript; and LJM, ML, and AT: nerveless the data and wrote the manuscript. None of the authors had a conflict of interest to disclose.
FOOTNOTES
two We certify that none of the material in this manuscript was previously published, and the study was not funded.
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