Table 1. Characteristics of selected studies.
| Study (reference) | Study aim | Participants | Intervention group: intake details (total daily dose)a | n | Control group | n | Duration | Study design | Masking | Blood test for liver function |
|---|---|---|---|---|---|---|---|---|---|---|
| Princen et al.19 | Efficacy | Healthy volunteers | Green tea beverage: six cups (150 ml each) daily (851.7 mg catechins) | 15b | Water | 15b | 4 Weeks | Parallel | Single | — |
| Green tea polyphenol isolate CAPs: 4 CAPs 6 times daily (2488.7 mg catechins) | 13b | |||||||||
| Chow et al.20 | Safety | Healthy volunteers | EGCG CAPs: four CAPs daily (800 mg EGCG) | 8 | Placebo | 8 | 4 Weeks | Parallel | Single | Yes |
| EGCG CAPs: 2 CAPs twice daily (800 mg EGCG) | 8 | |||||||||
| Poly E CAPs: 4 CAPs daily (800 mg EGCG) | 8 | |||||||||
| Poly E CAPs: 2 CAPs twice daily (800 mg EGCG) | 8 | |||||||||
| Maron et al.21 | Efficacy | Adults with mild to moderate hypercholesterolemia | GTE CAPs: one CAP daily (150 mg catechins) | 120 | Placebo | 120 | 12 Weeks | Parallel | Double | Yes |
| Ullmann et al.22 | Safety | Healthy men | EGCG CAPs: one CAP daily (50 mg EGCG) | 8 | Placebo | 2 | Single dose | Parallel | Double | — |
| EGCG CAPs: two CAPs daily (100 mg EGCG) | 8 | Placebo | 2 | |||||||
| EGCG CAPs: four CAPs daily (200 mg EGCG) | 8 | Placebo | 2 | |||||||
| EGCG CAPs: eight CAPs daily (400 mg EGCG) | 8 | Placebo | 2 | |||||||
| EGCG CAPs: 16 CAPs daily (800 mg EGCG) | 8 | Placebo | 2 | |||||||
| EGCG CAPs: 32 CAPs daily (1600 mg EGCG) | 8 | Placebo | 2 | |||||||
| Sonoda et al.23 | Efficacy | Asymptomatic HTLV-1 carriers | GTE CAPs: nine CAPs daily (245.7 mg EGCG) | 47 | No treatment | 48 | 5 Months | Parallel | Open | — |
| Ullmann et al.24 | Safety | Healthy men | EGCG CAPs: four CAPs daily (200 mg EGCG) | 9 | Placebo | 3 | 10 Days | Parallel | Double | Yes |
| EGCG CAPs: eight CAPs daily (400 mg EGCG) | 9 | Placebo | 3 | |||||||
| EGCG CAPs: 16 CAPs daily (800 mg EGCG) | 9 | Placebo | 3 | |||||||
| Bettuzzi et al.25 | Efficacy | High-grade prostate intraepithelial neoplasia | Green tea catechin CAPs: three CAPs daily (600 mg catechins) | 30 | Placebo | 30 | 1 Year | Parallel | Double | — |
| Chan et al.26 | Efficacy | Women with polycystic ovary syndrome | Green tea CAPs: sic CAPs daily (540 mg EGCG) | 18 | Placebo | 16 | 3 Months | Parallel | Double | — |
| Luo et al.27 | Efficacy | Patients at high-risk of liver cancer | GTP CAPs: four CAPs daily (500 mg GTPs) | 42 | Placebo | 41 | 3 Months | Parallel | Double | Yes |
| GTP CAPs: four CAPs daily (1000 mg GTPs) | 41 | |||||||||
| Auvichayapat et al.28 | Efficacy | Obese | Green tea CAPs: three CAPs daily (750 mg GTE) | 30 | Placebo | 30 | 12 Weeks | Parallel | Single | — |
| Hill et al.29 | Efficacy | Overweight post-menopausal women | EGCG CAPs: two CAPs daily (300 mg EGCG) | 19b | Placebo | 19b | 12 Weeks | Parallel | Single | Yes |
| Rowe et al.30 | Efficacy | Healthy volunteers | Green tea CAPs: one CAP twice daily | 55 | Placebo | 53 | 12 Weeks | Parallel | Double | — |
| Widlansky et al.31 | Efficacy | Patients with CAD | EGCG CAPs: one CAP twice daily (300 mg EGCG) | 54 | Placebo | 52 | 2 Weeks | Crossover (two-arm, 1-week washout) | Double | Yes |
| Hsu et al.32 | Efficacy | Obese women | GTE CAPs: three CAPs daily (1200 mg GTEs) | 50 | Placebo | 50 | 12 Weeks | Parallel | Double | Yes |
| Shimizu et al.33 | Efficacy | Healthy volunteers | GTE TABs: three TABs daily (1500 mg GTEs) | 68 | Water | 65 | 12 Months | Parallel | Open | — |
| Falsini et al.34 | Efficacy | Ocular hypertension and glaucoma | EGCG oral treatment: 200 mg EGCG oral treatment daily | 36b | Placebo | 36b | 3 Months | Crossover (two-arm, no washout) | Double | — |
| Janjua et al.35 | Efficacy | Healthy women | Green tea CAPs: one CAP twice daily (350 mg catechins) | 29 | Placebo | 27 | 2 Years | Parallel | Double | — |
| Tsao et al.36 | Efficacy | High-risk oral premalignant lesions | GTE CAPs: 500 mg/m2 GTE daily | 11 | Placebo | 11 | 12 Weeks | Parallel | Double | Yes |
| GTE CAPs: 750 mg/m2 GTE daily | 9 | |||||||||
| GTE CAPs: 1000 mg/m2 GTE daily | 10 | |||||||||
| Basu et al.37 | Efficacy | Obese and metabolic syndrome | Green tea beverage: four cups daily (928 mg catechins) | 13b | Water | 12b | 8 Weeks | Parallel | Single | Yes |
| GTE CAPs: two CAPs daily (870 mg catechins) | 10b | |||||||||
| Shen et al.38 | Efficacy | Postmenopausal women | GTP CAPs: two CAPs daily (500 mg GTPs) | 47 | Placebo | 44 | 24 Weeks | Parallel | Double | Yes |
| Thielecke et al.39 | Efficacy | Overweight men | EGCG CAPs: one CAP twice daily (300 mg EGCG) | 10 | Placebo | 10 | 3 Days | Crossover (five-arm, ⩾7- day washout) | Double | — |
| EGCG CAPs: one CAP twice daily (600 mg EGCG) | 10 | |||||||||
| Brown et al.40 | Efficacy | Overweight men | Decaffeinated GTE CAPs: one CAP twice daily (1060 mg GTEs) | 69 | Placebo | 72 | 6 Weeks | Crossover (two-arm, ⩾2- week washout) | Double | Yes |
| Hsu et al.41 | Efficacy | Obese type 2 DM patients | Decaffeinated GTE CAPs: one CAP three times daily (1500 mg GTEs) | 40 | Placebo | 40 | 16 Weeks | Parallel | Double | Yes |
| Hursel et al.42 | Efficacy | Healthy volunteers | Green tea CAPs: three CAPs daily (507 mg catechins) | 18 | Placebo | 18 | 1 Week | Crossover (six-arm, no washout) | Single | — |
| Matsumoto et al.43 | Efficacy | Healthy volunteers | Green tea CAPs: six CAPs daily (378 mg catechins) | 97 | Placebo | 99 | 5 Months | Parallel | Double | — |
| Ronzani et al.44 | Efficacy | Patients with breast cancer | GTE TABs: two TABs twice daily (800 mg catechins) | 46 | No treatment | 46 | 3 Weeks | Crossover (two-arm, 1-day washout) | Open | — |
| Crew et al.45 | Safety | Women with hormone receptor-negative breast cancer | Poly E CAPs: two CAPs twice daily (800 mg EGCG) | 13b | Placebo | 8b | 6 Months | Parallel | Double | Yes |
| Poly E CAPs: three CAPs twice daily (1200 mg EGCG) | 6b | |||||||||
| Poly E CAPs: four CAPs twice daily (1600 mg EGCG) | 1b | |||||||||
| Dash et al.46 | Efficacy | Smoker and non-smoker | Green tea beverage: five packets daily (640 mg catechins) | 45 | Placebo | 48 | 4 Weeks | Crossover (4-arm, 2- week washout) | Double | — |
| Loftis et al.47 | Efficacy | Schizophrenia and bipolar disorder | GTE CAPs: two CAPs twice daily (600 mg GTE) | 16 | Placebo | 15 | 8 Weeks | Parallel | Double | Yes |
| Nguyen et al.48 | Efficacy | Prostate cancer | Poly E CAPs: four CAPs daily (800 mg EGCG) | 25 | Placebo | 25 | 3–6 Weeks | Parallel | Double | Yes |
| Yoshikawa et al.49 | Efficacy | Healthy volunteers | GTE CAPs: three CAPs three times daily (1069.4 mg catechins) | 20 | Placebo | 20 | 1 Weeks | Parallel | Double | Yes |
| Dryden et al.50 | Efficacy | Patients with mild to moderate ulcerative colitis | Poly E CAPs: one CAP twice daily (400 mg EGCG) | 5b | Placebo | 1b | 56 Days | Parallel | Double | Yes |
| Poly E CAPs: two CAPs twice daily (800 mg EGCG) | 8b | Placebo | 2b | |||||||
| Roshdy et al.51 | Efficacy | Women with uterine fibroids | GTE CAPs: two CAPs daily (360 mg EGCG) | 22 | Placebo | 17 | 4 Months | Parallel | Double | Yes |
| Toolsee et al.52 | Efficacy | Prediabetic mauritians | Green tea beverage: one cup (200 ml) three times daily (1519.7 mg green tea catechins) | 77 | Water | 78 | 14 Weeks | Parallel | Open | Yes |
Abbreviations: CAD, coronary artery disease; CAP, capsule; DM, diabetes mellitus; EGCG, epigallocatechin gallate; GTE, green tea extract; GTP, green tea polyphenol; HTLV-1, human T-cell lymphotropic virus type 1; Poly E, polyphenon E; TAB, tablet.
a
Intake details shown as explained in the reference, and total daily dose if available in the reference.
b
Number of subjects who completed the study.