Table 1 Characteristics of studies that reported the potential roles of green tea extract (GTE) on PCOS

Animal studies

Sadoughi et al. 2017 [21]

42 Wistar female rats were divided into 7 equal groups: control, PCOS control, PCOS treated with aqueous extract of green tea (50 and 100 mg/kg, PCOS treated with catechin (50 and 100 mg/kg) and PCOS treated with clomiphene citrate (1.5 mg/kg, 24 days).

50,100 mg/kg/day GTE

24 day

- Serum level of LH, β-estradiol, and testosterone significantly decreased.

- Serum level of FSH, progesterone significantly increased.

- Number of preantral, antral, preovulatory follicles, and corpus luteum significantly increased.

Rahbarian et al. 2017 [22]

24 Wistar female rats were divided into 4 equal groups: control (saline solution), non-treated PCOS (saline solution) and PCOS treated with catechin (50 and 100 mg/kg, 24 days).

50,100 mg/kg/day GTE

24 day

-Serum levels of TNF-α, IL-1β, MDA and IL-6 decreased

-SOD, CAT, GPX in ovarian tissue significantly increased.

Ghafurniya et al. 2015 [23]

96 Wistar rats were divided into 4 groups: PCOS group, three experimental groups, which were given 50, 100 and 200 mg/Kg BW green tea extract 10 days, intraperitoneally.

50,100,200 mg/kg/day GTE

10 day

-LH serum level, body weight and ovarian weight decreased

-Insulin resistance and blood glucose decreased

-Improved of ovarian function

Ghafurniya et al. 2014 [24]

40 Wistar rats were divided into 5 groups: PCOS rats received no injections (PCOS control), rats received saline (sham), PCOS rats that received of 50 mg/kg of green tea extract (GT-Treated-1), rats that were received intraperitoneal injection 100 mg/kg of green tea extract (GT-Treated-2), rats that were received intraperitoneal injection 200 mg/kg of green tea extract (GT-Treated-3).

50,100,200 mg/kg/day GTE

2 weeks

–CRP and IL-6 serum levels reduced.

–Improved follicular layers thickness (improving of ovarian function)

Human studies

Mombaini et al. 2017 [25]

45 women with PCOS were randomly allocated into 2 groups receiving GT tablets or placebo

500-mg/day GTE

1.5 months

- Significant decrease in BMI, body weight, waist circumference, and body fat percentage.

-No effect on the levels of inflammatory factors (IL-6, hs-CRP, TNF-α)

Tehrani et al. 2017 [26]

60 Overweight women with PCOS were given GTE

500 mg/day GTE capsules

3 months

– Significant decrease in Body weight, FBG, serum insulin and free testosterone.

Allahdadian et al. 2015 [27]

60 overweight or obesity women with PCOS were received GTE tablets and placebo.

500 mg/day GTE

3 months

- Significant decrease in BMI and body weight.

-Significant decrease in FBS, in sulinand free testosterone levels

Chan et al. 2005 [28]

34 obese Chinese women with PCOS were randomized into either treatment with GTE capsules or placebo.

1.5 cups of 2% Lung Chen tea (an equivalent of 540 mg EGCG)

3 months

-No significant effect on body weight, BMI, body fat, total testosterone, SHBG, Free androgen index, DHEA-S, FSH, LH.