The effects of green tea supplementation on cardiovascular risk factors: A systematic review and meta-analysis

Mohammad Zamani; Mahnaz Rezaei Kelishadi; Damoon Ashtary-Larky; Niusha Amirani; Kian Goudarzi; Iman Attackpour Torki; Reza Bagheri; Matin Ghanavati; Omid Asbaghi

doi:10.3389/fnut.2022.1084455

The effects of green tea supplementation on cardiovascular risk factors: A systematic review and meta-analysis

Front Nutr. 2023 Jan 10:9:1084455. doi: 10.3389/fnut.2022.1084455. eCollection 2022.

Authors

Mohammad Zamani¹, Mahnaz Rezaei Kelishadi², Damoon Ashtary-Larky³, Niusha Amirani⁴, Kian Goudarzi⁵, Iman Attackpour Torki⁶, Reza Bagheri⁷, Matin Ghanavati⁸, Omid Asbaghi^{9

10}

Affiliations

¹ Department of Clinical Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran.
² Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran.
³ Nutrition and Metabolic Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
⁴ Faculty of Medicine, Alborz University of Medical Sciences, Tehran, Iran.
⁵ Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
⁶ Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran.
⁷ Department of Exercise Physiology, University of Isfahan, Isfahan, Iran.
⁸ National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
⁹ Cancer Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
¹⁰ Student Research Committee, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

Abstract

Purpose: A bulk of observational studies have revealed the protective role of green tea supplementation in cardiovascular diseases. The current systematic review and meta-analysis study aimed to establish the effects of green tea supplementation on cardiovascular risk factors including lipid profile, blood pressure, glycemic control markers and CRP.

Methods: A systematic literature search of randomized clinical trials (RCTs) that investigated the effects of green tea supplementation and cardiovascular risk factors was undertaken in online databases including PubMed/Medline, Scopus, Web of Science, and Embase using a combination of green tea and cardiovascular risk factors search terms. Meta-analyses were carried out using a random-effects model. The I² index was used to assess the heterogeneity of RCTs.

Results: Among the initial 11,286 studies that were identified from electronic databases search, 55 eligible RCTs with 63 effect sizes were eligible. Results from the random effects meta-analysis showed that GTE supplementation significantly reduced TC (WMD = -7.62; 95% CI: -10.51, -4.73; P = < 0.001), LDL-C (WMD = -5.80; 95% CI: -8.30, -3.30; P = < 0.001), FBS (WMD = -1.67; 95% CI: -2.58, -0.75; P = < 0.001), HbA1c (WMD = -0.15; 95% CI: -0.26, -0.04; P = 0.008), DBP (WMD = -0.87; 95% CI: -1.45, -0.29; P = 0.003), while increasing HDL-C (WMD = 1.85; 95% CI: 0.87, 2.84; P = 0.010). Subgroup analyses based on the duration of supplementation (≥ 12 vs. < 12 weeks), dose of green tea extract (GTE) (≥1,000 vs. < 1,000 mg/d), sex (male, female, and both), baseline serum levels of lipid profile, and glycemic control factors demonstrated different results for some risk factors.

Conclusion: The current study suggests improvements in the lipid and glycemic profiles following green tea supplementation. These findings support previous evidence showing the health benefits of green tea supplementation on cardiometabolic risk factors.

Keywords: blood pressure; cardiovascular risk factors; glycemic control; green tea supplementation; lipid profile; meta-analysis; systematic review.

Publication types

Review