The Effect of Dietary Supplementation of Green Tea Catechins on Cardiovascular Disease Risk Markers in Humans: A Systematic Review of Clinical Trials
Abstract
:1. Introduction
2. Methods/Design
2.1. Search Terminology
2.2. Selection Criteria and Data Extraction
2.3. Outcomes
2.4. Data Analysis
3. Results
3.1. Search in Literature
3.2. Risk of Bias in Included Studies
3.3. Results of the Selected Studies
4. Discussion
5. Conclusions
Acknowledgments
Author Contributions
Conflicts of Interest
Abbreviations
CVD | Cardiovascular Disease |
BP | Blood Pressure |
LDL-C | Low Density Lipoprotein Cholesterol |
HDL-C | High Density Lipoprotein Cholesterol |
TC | Total Cholesterol |
WC | Waist Circumference |
BMI | Body Mass Index |
GT | Green Tea |
GTC | Green Tea Catechins |
EGCG | Epigallocatechin Gallate |
EGC | Epigallocatechin |
ECG | Epicatechin Gallate |
EC | Epicatechin |
PRISMA | Preferred Reporting Items for Systematic Reviews and Meta-Analyses |
RIA | Immunoradiometric Assay |
TNF-α | Tumor Necrosis Factor-α |
CRP | C-Reactive Protein |
SBP | Systolic Blood Pressure |
DBP | Diastolic Blood Pressure |
TG | Triglycerides |
HOMA-IR | Homeostatic Model Assessment for Insulin Resistance |
TAS | Total Antioxidant Status |
NA | Noradrenaline |
GLP-1 | Glucagon-Like Peptide 1 |
wt | Weight |
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Author (Year) | Participants, Sample Size | Aim | Intervention | Outcomes (Treatment Group vs. Placebo) |
---|---|---|---|---|
Bogdanski et al. (2012) [9] | All (n = 56) (28 Male and 28 Female, 30–60 years old) Age: 50.4 ± 8.1 years Treatment (n = 28), Placebo (n = 28) Obese, hypertensive adults | Effect of GT supplementation on insulin resistance and associated cardiovascular risk factors in obese, hypertensive subjects. | Treatment (capsules 379 mg GTE/day) or placebo for three months. Total GTCs = n.r. EGCG = 208 mg/day | A: (↔BMI, WC: p > 0.05) ↓BP (SBP: p = 0.04, DBP: p < 0.001) Biochem: (↔TC: p = 0.09, ↓LDL-C: p = 0.011, ↑HDL-C: p < 0.01, ↓TG: p = 0.004) |
Chen et al. (2015) [10] | Female only (n = 77, 20–60 years old) Treatment (n = 39) Placebo (n = 38), Age: 44.5 ± 11.5 years) abdominal obesity with BMI ≥ 27 kg/m2 and WC ≥ 80 cm | Effect and safety of high-dose GTE on weight reduction and changes of lipid profile in women with abdominal obesity. | Treatment (opaque capsules 1500 mg GTE/day) or placebo for 12 weeks. Total GTCs = 1344 mg EGCG = 856.8 mg, ECG = 236.1 mg EGC = 115.5 mg, EC = 71.9 mg, GCG = 637 mg | A: (↓wt: p = 0.025, ↓BMI: p = 0.018, ↓WC: p = 0.023) ↔BP (SBP: p = 0.795, DBP: p = 0.929) Biochem: (↓TC: p = 0.005, ↓LDL-C: p = 0.006, ↔HDL-C: p = 0.208, ↔TG: p = 0.778) |
Diepvens et al. (2006) [11] | Female only (n = 46 19–57 years old) Age: 41.6 ± 9.3 years, Treatment (n = 23) Placebo (n = 23), Overweight with 25 kg/m2 <BMI> 35 kg/m2 | Effect of GTE ingestion with a low-energy diet on health-related blood parameters and its relationships with changes in metabolic parameters and weight loss. | Treatment (capsules 1206.9 mg GTE/day) or placebo for 12.4 weeks. Total GTCs = 522 mg, EGCG = 264.8 mg ECG = 94.4 mg, EGC = 106.8 mg EC = 56 mg, GCG = n.r. | A: (↓wt, BMI, WC: p < 0.01) ↓BP (SBP: p < 0.01, DBP: p < 0.05) Biochem: (↓TC: p < 0.05, ↓LDL-C: p > 0.05, ↓HDL-C: p < 0.05, ↔TG: p > 0.05) * no direct test between groups |
Hsu et al. (2011) [12] | All (n = 68, 20–65 years old) (24 Male and 44 Female), Age: 51.3 ± 9.1 years Obese; type 2 diabetes Treatment (n = 35), Placebo (n = 33) | Effects of decaffeinated GTE on obese individuals with type 2 diabetes. | Treatment decaffeinated GTE (opaque capsules 1500 mg GTE/day) or placebo for 16 weeks. Total GTCs = 1344 mg, EGCG = 856.8 mg, ECG = 236.1 mg, EGC = 115.5 mg EC = 71.9 mg, GCG = 637mg | A:(↔BMI: p = 0.43, ↔WC: p = 0.06) ↔BP (SBP: p = 0.68, DBP: p = 0.86) Biochem: ↔ (TC: p = 0.39, LDL-C: p = 0.24, HDL-C: p = 0.78, TG: p = 0.66) |
Hsu et al. (2008) [13] | Female only (n = 78, 16–60 years old) Age: 43.5 ± 11.8 years, Treatment (n = 41) Placebo (n = 37), Obese (BMI > 27 kg/m2) | Effects of GTE on obese women and obesity-related peptide hormones. | Treatment (opaque capsules 400 mg GTE/day) or placebo for 12 weeks. Total GTCs = 605.26 mg EGCG = 377.2 mg, ECG = 31.76 mg EGC = 36.91 mg, GC = 61.58 mg, GCG = 27.48 mg | A: (↔wt: p > 0.05, ↔BMI: p > 0.05, ↓WC: p < 0.05) ↔BP (SBP, DBP: p > 0.05) Biochem (↔TC: p > 0.05, ↓LDL-C: p < 0.001, ↔HDL-C: p > 0.05, ↓TG: p < 0.001) |
Liu et al. (2014) [14] | All (n = 77, 20–65 years old) (32 Male and 45 Female), Age: 54.3 ± 6.8 years Treatment (n = 39), Placebo (n = 38) Dyslipidaemic adults with type 2 diabetes | Effects of GTE on lipid profiles in participants with type 2 diabetes and dyslipidaemia. | Treatment (capsules 1500 mg GTE/day) or placebo for 16 weeks. Total GTCs = 1344 mg EGCG = 856.8 mg, ECG = 236.1 mg EGC = 115.5 mg, EC = 71.9 mg, GCG = 637 mg | A: ↔ (BMI: p = 0.06, WC: p = 0.17, wt: p = 0.09) ↔BP (SBP: p = 0.48, DBP: p = 0.68) Biochem: (↔TC: p = 0.67, ↔LDL-C: p = 0.55, ↑HDL-C: p = 0.04, ↓TG: p = 0.03) |
Nagao et al. (2009) [15] | All (n = 43) (18 Male and 25 Female, < 65 years old) Treatment (n = 23) Control (n = 20), Age: 63.8 ± 1.9 years Type 2 diabetics | Effects of continuous ingestion of a catechin-rich beverage in type 2 diabetes who were not receiving insulin therapy. | Treatment (beverage 582.8 mg GTCs/day) or Control (96.3 mg GTCs/day) for 12 weeks. Total GTC = 582.8 Individual = n.r. | A: (↔BMI: p > 0.05, ↔wt: p > 0.05, ↓WC: p < 0.05) ↔BP (SBP, DBP: p > 0.05) Biochem: (↓TC: p < 0.05, ↔LDL-C: p > 0.05, ↔HDL-C: p > 0.05, ↔TG: p > 0.05) |
Bias Category | Bogdanski et al. (2012) [9] | Chen et al. (2015) [10] | Diepvens et al. (2006) [11] | Hsu et al. (2008) [13] | Hsu et al. (2011) [12] | Liu et al. (2014) [14] | Nagao et al. (2009) [15] |
---|---|---|---|---|---|---|---|
Random Sequence Generation (selection bias) | Low | Low | Moderate | Low | Low | Moderate | Moderate |
Blinding of participants and personnel (performance bias). | Low | Low | Low | Low | Low | Low | Low |
Blinding of outcome assessment (detection bias) (mortality) | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear |
Incomplete data addressed (attrition bias) | Low | Low | Unclear | Moderate | Low | Low | Low |
Selective reporting (reporting bias) | Low | Low | Low | Low | Low | Low | Low |
Other bias | Low | Low | Low | Low | Low | Low | Low |
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Lau, S.O.; Georgousopoulou, E.N.; Kellett, J.; Thomas, J.; McKune, A.; Mellor, D.; Roach, P.D.; Naumovski, N. The Effect of Dietary Supplementation of Green Tea Catechins on Cardiovascular Disease Risk Markers in Humans: A Systematic Review of Clinical Trials. Beverages 2016, 2, 16. https://doi.org/10.3390/beverages2020016
Lau SO, Georgousopoulou EN, Kellett J, Thomas J, McKune A, Mellor D, Roach PD, Naumovski N. The Effect of Dietary Supplementation of Green Tea Catechins on Cardiovascular Disease Risk Markers in Humans: A Systematic Review of Clinical Trials. Beverages. 2016; 2(2):16. https://doi.org/10.3390/beverages2020016
Chicago/Turabian StyleLau, Sarah O., Ekavi N. Georgousopoulou, Jane Kellett, Jackson Thomas, Andrew McKune, Duane Mellor, Paul D. Roach, and Nenad Naumovski. 2016. "The Effect of Dietary Supplementation of Green Tea Catechins on Cardiovascular Disease Risk Markers in Humans: A Systematic Review of Clinical Trials" Beverages 2, no. 2: 16. https://doi.org/10.3390/beverages2020016
APA StyleLau, S. O., Georgousopoulou, E. N., Kellett, J., Thomas, J., McKune, A., Mellor, D., Roach, P. D., & Naumovski, N. (2016). The Effect of Dietary Supplementation of Green Tea Catechins on Cardiovascular Disease Risk Markers in Humans: A Systematic Review of Clinical Trials. Beverages, 2(2), 16. https://doi.org/10.3390/beverages2020016