Table 4. Association between testosterone and the bacterial composition and diversity.

Summary of findings gathered in the four studies that investigated the association between testosterone and bacterial composition and/or diversity. Three of these investigated its effects on composition while one explored the effects on diversity.

N/A: not applicable; PCOS: polycystic ovary syndrome; PCOM: polycystic ovarian morphology.

Study	Testosterone
	Bacterial Composition	Bacterial Diversity
Chu et al.(33)	↑ Four of the species related to PCOS (Enterobacteriaceae family) ↓ Species found to be related to healthy women	N/A
Liang et al.(29)	↑ Prevotella-9 genus ↓ Several species including Subdoligranulum, Halli-group, Fusicatenibacter, Lachospiraceae, Ruminococcaceae, Ruminiclostridium, Tyzzerella (Healthy women, normal-weight women with PCOS and obese women with PCOS considered as a whole)	N/A
Liu et al.(27)	↑ Multiple genera including Escherichia/Shigella, Streptococcus, Clostridium XlVa, and Rothia ↓ Multiple genera including Akkermansia, Collinsella and Ruminococcus	N/A
Torres et al.(31)	N/A	↓ Alpha diversity ↔ Beta diversity between groups (All observed in a cohort of healthy women and women with PCOM and PCOS)

^*↑ denotes a positive association between the sex hormone and the outcome of interest.

^*↓ denotes a negative/inverse association between the sex hormone and the outcome of interest.

^*↔ denotes a lack of association found between the sex hormone and the outcome of interest