The Anti-Obesity Effects of Green Tea: A Controlled, Randomized, Clinical Trial

Abstract

Background: Obesity is a global health threatening issue with increasing prevalence in the developed and developing world. The limited efficacy and side effects of conventional treatments motivated the researchers to look for novel, safe, and effective therapeutic strategies. Objectives: The current study aimed at investigating the anti-obesity effects of green tea in a population in North of Iran. Methods: The current single-blind, placebo-controlled, parallel, clinical trial was conducted in Guilan outpatient clinic in Rasht, Iran, from January to December 2015. Eligible subjects were randomly allocated into 2 groups of green tea and control. In the GT Group, a cup of green tea and in the C group an equal amount of mineral water was taken 30 minutes after breakfast and lunch. The outcomes including body weight (BW), body mass index (BMI), hip circumference, waist circumference, and waist-to-hip ratio were measured at baseline, as well as 8 and 12 weeks after the intervention (T0,T_1, T_2).Results: Finally, data obtained from 84 cases in groups GT (n = 41) and C (n = 43) were analyzed. No significant difference was observed in terms of baseline demographics and measurements between the 2 groups including male/female (P = 0.766), age (P = 0.376), weight (P = 0.846), height (P = 0.413), waist circumference (P = 0.619), hip circumference (P = 0.619), and waist-to-hip ratio (P = 0.301). According to the intragroup analyses, the trend of changes from baseline to 12 weeks after intervention were significant in both groups (P = 0.001); BW (79.88 ± 7.06 to 72.44 ± 6.82 kg) and (80.21 ± 7.16 to77.07 ± 7.22 kg) , BMI (29.95 ± 1.79 to 26.86 ± 2.59 kg/m 2 ) and (29.69 ± 2.1 to 27.07 ± 2.22 kg/m 2 ) , waist circumference (87.77±6.06 to 83.913 ± 6.13 cm) and (86.94 ± 8.05 to 85.23 ± 7.89 cm), and hip circumference (102.41 ± 7.35 to 98.3 ± 7.54 cm) and (101.02 ± 8.47 to 99.31 ± 8.81 cm) in GT and C groups, respectively. However no such difference was observed in waist/hip ratio in the GT and C groups (P = 0.087) and (P = 0.322), respectively. A significant difference was observed at T1 (P = 0.024 and P = 0.025) and T2 (P = 0.025 and P = 0.006), according to weight and BMI, respectively. However, the differences were not statistically significant based on the other variables. Conclusions: Green tea could be a safe and effective choice for patients with obesity. However, further well-designed trials are required to confirm these findings.

The effect of green tea supplementation on obesity: A systematic review and dose–response meta‐analysis of randomized controlled trials

“…During the full-text review stage, 426 articles were excluded based on the following reasons: non-clinical trials, whole GT was not employed in the intervention (the studies employed decaffeinated green tea extract or green tea catechin), animal study, GT was employed in combination with other components, the studies were performed in children, insufficient data, lack of appropriate control groups, duplicate datasets. Finally, 25 articles with 26 arms were included in this meta-analysis (Afzalpour, Ghasemi, & Zarban, 2017;Al-Naggar, Osman, & Abdulghani, 2013;Amozadeh, Shabani, & Nazari, 2018;Auvichayapat et al, 2008;Basu et al, 2011;Bogdanski et al, 2012;Cardoso, Salgado, Cesar Mde, & Donado-Pestana, 2013;Chan et al, 2006;Di Pierro, Menghi, Barreca, Lucarelli, & Calandrelli, 2009;Diepvens, Kovacs, Nijs, Vogels, & Westerterp-Plantenga, 2005;Hovanloo, Fallah Huseini, Hedayati, & Teimourian, 2016;Hsu et al, 2008;Hsu et al, 2011;Hussain, Habib Ur, & Akhtar, 2017;Kovacs, Lejeune, Nijs, & Westerterp-Plantenga, 2004;Mombaini, Jafarirad, Husain, Haghighizadeh, & Padfar, 2017;Nabi et al, 2018;Rostamian & Bijeh, 2017;Soeizi et al, 2017;Suliburska et al, 2012;Tabatabaee et al, 2017;Toolsee et al, 2013;Venkatakrishnan et al, 2018;Vieira Senger, Schwanke, Gomes, & Valle Gottlieb, 2012) (Supplemental Figure 1).…”

“…These studies were published between 2004 and 2018. Eligible studies were performed in: Taiwan (Hsu et al, 2008;Hsu et al, 2011;Venkatakrishnan et al, 2018), Iran (Afzalpour et al, 2017;Amozadeh et al, 2018;Hovanloo et al, 2016;Hussain et al, 2017;Mombaini et al, 2017;Nabi et al, 2018;Rostamian & Bijeh, 2017;Soeizi et al, 2017), Pakistan (Hussain et al, 2017), China (Chan et al, 2006), The Netherlands (Diepvens et al, 2005;Janssens, Penders, et al, 2016;Kovacs et al, 2004), Malaysia (Al-Naggar et al, 2013), the United States of America (Basu et al, 2011), Toolsee et al, 2013), Brazil (Cardoso et al, 2013;Vieira Senger et al, 2012), Poland (Bogdanski et al, 2012;Suliburska et al, 2012), Italy (Di Pierro et al, 2009), and Thailand (Auvichayapat et al, 2008). The follow-up period ranged from 2 weeks to 5 months.…”

“…The studies involved a range of 18 to 104 participants. Chan et al, 2006;Di Pierro et al, 2009;Diepvens et al, 2005;Hovanloo et al, 2016;Hsu et al, 2008;Hsu et al, 2011;Hussain et al, 2017;Janssens, Penders, et al, 2016;Kovacs et al, 2004;Mombaini et al, 2017;Nabi et al, 2018;Rostamian & Bijeh, 2017;Soeizi et al, 2017;Suliburska et al, 2012;Tabatabaee et al, 2017;Toolsee et al, 2013;Venkatakrishnan et al, 2018;Vieira Senger et al, 2012). Most studies were rated as good quality across the Cochrane items.…”

Plant Extracts and Reactive Oxygen Species as Two Counteracting Agents with Anti- and Pro-Obesity Properties

“…A significant decrease in body weight and BMI were observed in beverage and supplementation groups as a consequence of elevated oxidation and lipolysis. Elsewhere, significant decreases of weight and BMI were also observed among patients consuming 150 mL green tea beverage two times a day for eight and 12 weeks compared to controls administered placebo [184]. The study included 99 subjects with a BMI of 24–35 and age between 18–50.…”

Large-Scale Target Identification of Herbal Medicine Using a Reverse Docking Approach

“…1 The power of herbal therapeutics has attracted increasing attentions. Each year, an increasing number of publications described the mechanism of action (MOA) underlying herbs such as ginseng, 2 echinacea, 3 green tea, 4 and ginger. 5 Some herbal ingredients such as pancratistatin 6 and paclitaxel 7 have been applied in cancer therapy.…”