It was found that Ghrelin and PYY were significantly lower in PCOS patients compared with normal women, while serum LH levels and LH/FSH ratio were significantly reduced after successful probiotic transplantation, and improved PCOS-related clinical indicators and increased SCFA levels; while no significant changes were seen in serum LH and SCFA levels in the unsuccessful probiotic transplantation group (Zhang J. et al., 2019). Here, PYY is linked to polycystic ovary syndrome.