Additionally, SCFA levels are often reduced in PCOS patients; however, supplementation with probiotic Lactobacillus bifidus V9 has been shown to restore SCFA production, balance hormone levels, and reduce LH/FSH ratios, suggesting a role for SCFAs in gut-brain axis-mediated regulation of the central nervous system (Zhang et al., 2019). This evidence concerns the gene PLOD1 and polycystic ovary syndrome.