Table 1. Characteristic of RCTs included in the meta-analysis.

First authorref	Sample size	Treatments duration (months)	Population	Tea or tea extract group	Control group	Type of diet, lifestyle and exercise status
Chu et al.25	90	3	Chinese, overweight/obese and hyperlipidemia, MetS according to Chinese diagnosis criteria; 50 years of mean age (18 years)	1000 mg Puerh tea water extract filled in eight capsules	Placebo (cellulose capsule)	Adviced on a healthy diet
Basu et al.26, 27, 28, 29	35	2	Overweight/obese, MetS according to ATP III; matched for age (±5 years) and gender; 42.5 years of mean age (21 years)	Green tea (4 cups, 928 mg catechins) or green tea extract (2 capsules, 870 mg catechins)	Water (4 cups)	Maintained usual diet, physical activity and lifestyle
Vieira Senger et al.30	45	2	MetS according to IDF diagnosis criteria; elderly people (60 years)	Three sachets of 1000 mg of green tea	No treatment	Maintained usual diet, physical activity and lifestyle
Belcaro et al.31	98	6	Borderline profile for all five MetS factors according to IDF diagnosis criteria; 46.5 years of mean age (45 years)	300 mg green tea extract devoid of caffeine and formulated in lecithin	Placebo (blank formulation)	Management plan (made changes in diet, thus avoiding junk food and limiting high-calorie elements and also a precise individual exercise plan)
Yang et al.32	70	3	Chinese, overweight/obese, MetS according to IDF diagnosis criteria; 59.2 years of mean age	999 mg Puerh tea extract in three capsules	Placebo (dextrin)	No change for dietary intervention or previous medication(s)

Abbreviations: ATP III, Adult Treatment Panel III; IDF, International Diabetes Federation; MetS, metabolic syndrome; RCTs, randomized controlled trials.