Green Tea Catechins Decrease Total and Low-Density Lipoprotein Cholesterol: A Systematic Review and Meta-Analysis

doi:10.1016/j.jada.2011.08.009

Journal of the American Dietetic Association

Volume 111, Issue 11, November 2011, Pages 1720-1729

https://doi.org/10.1016/j.jada.2011.08.009 Get rights and content

Abstract

Green tea catechins (GTCs) have been studied in randomized control trials for their lipid-lowering effects. Studies, however, have been small and demonstrated conflicting results. The objective of this study was to perform a systematic review and meta-analysis of randomized controlled trials evaluating the relationship between GTCs and serum lipid levels, including total, low-density lipoprotein (LDL), high-density lipoprotein (HDL) cholesterol, and triglycerides. A systematic literature search of MEDLINE, EMBASE, Cochrane CENTRAL, and the Natural Medicines Comprehensive Database was conducted through March 2010. Randomized controlled trials evaluating GTCs vs control in human beings and reporting efficacy data on at least one of the aforementioned serum lipid endpoints were included. Weighted mean differences for changes from baseline (with 95% confidence intervals [CIs]) for lipid endpoints were calculated using random-effects models. Twenty trials (N=1,415) met all inclusion criteria. Upon meta-analysis, GTCs at doses ranging from 145 to 3,000 mg/day taken for 3 to 24 weeks reduced total (−5.46 mg/dL [−0.14 mmol/L]; 95% CI −9.59 to −1.32) and LDL cholesterol (−5.30 mg/dL [−0.14 mmol/L]; 95% CI −9.99 to −0.62) compared to control. GTCs did not significantly alter HDL cholesterol (−0.27 mg/dL [−0.007 mmol/L]; 95% CI −1.62 to 1.09) or triglyceride (3.00 mg/dL [−0.034 mmol/L]; 95% CI −2.73 to 8.73) levels. The consumption of GTCs is associated with a statistically significant reduction in total and LDL cholesterol levels; however, there was no significant effect on HDL cholesterol or triglyceride levels.

Section snippets

Study Selection

A systematic literature search was conducted through March 2010 in the following databases: MEDLINE (beginning 1950), EMBASE (beginning 1990), Cochrane Central Register of Controlled Trials (Indexed January 2010), and the Natural Medicines Comprehensive Database. A search strategy was performed combining the Medical Subject Headings and text keywords “tea,” “green tea,” “green tea extract,” “catechin,” “EGCG,” “tea polyphenols,” “theaflavin,” or “Camelia sinesis,” with “total cholesterol,” “LDL

Study Characteristics

Of the 130 nonduplicate citations retrieved, 30 full-text articles underwent detailed evaluation (Figure 1). Ten full-text articles were excluded because relevant endpoints were not reported. Ultimately, 20 trials (N=1,415) (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28) were included in the systematic review (Table 1) with 19 trials reporting results on total cholesterol (9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28), 19 reporting

Discussion

Observational data shows conflicting results of the effect of green tea on lipid parameters. Consumption of up to 4 cups green tea per day was not associated with changes in lipid parameters (7), but >10 c/day was associated with reductions in total and LDL cholesterol levels and increases in HDL cholesterol level (32). Interest in health benefits of green tea prompted proposed health claims on labels of green tea products. However, in 2005, the Food and Drug Administration concluded that there

Conclusions

Based on currently available literature, GTCs may have a beneficial effect on total and LDL cholesterol levels in human beings. However, there is no statistically significant effect on HDL cholesterol or triglyceride levels. Future studies should be conducted to determine the ideal dose and duration of GTCs. The effect of specific catechins components should also be further investigated because there may be an additive or synergistic effect on lipid values. Further investigations should be

A. Kim is a pharmacy practice resident, University of Connecticut School of Pharmacy, Hartford, CA.

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A. Kim is a pharmacy practice resident, University of Connecticut School of Pharmacy, Hartford, CA.

A. Chiu is a research scientist, University of Connecticut School of Pharmacy, Hartford, CA.

M. K. Barone is a research scientist, University of Connecticut School of Pharmacy, Hartford, CA.

F. Wang is an associate clinical professor of pharmacy practice, University of Connecticut School of Pharmacy, Hartford, CA.

C. I. Coleman is an associate professor of pharmacy practice, University of Connecticut School of Pharmacy, Hartford, CA.

O. J. Phung is an assistant professor of pharmacy practice, College of Pharmacy, Western University of Health Sciences, Pomona, CA.

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ResearchReviewGreen Tea Catechins Decrease Total and Low-Density Lipoprotein Cholesterol: A Systematic Review and Meta-Analysis

Abstract

Section snippets

Study Selection

Study Characteristics

Discussion

Conclusions

Biochem Biophys Acta

Ann Epidemiol

Ann Epidemiol

J Nutr

J Nutr

Nutrition

Clin Nutr

Diabet Res Clin Prac

J Nutr Biochem

Am J Clin Nutr