As shown in Fig. 4, pooling effect sizes from 3 RCTs15–17 with 171 subjects showed a non-significant reduction in FBS (WMD = − 1.08 mg/dL, 95% CI − 5.07 to 2.91), insulin (WMD = − 1.47 μIU/mL, 95% CI − 4.15 to 1.22), HOMA-IR (WMD = − 0.40, 95% CI − 0.95 to 0.15) and no change in QUICKI (WMD = 0.01, 95% CI 0.00–0.02) in PCOS patients after vitamin E supplementation or vitamin E along with omega-3 or magnesium supplementation, as compared to placebo. Here, INS is linked to polycystic ovary syndrome.