Gut microbiota may be involved in the development of polycystic ovary syndrome, according to a scientific study.

What is polycystic ovary syndrome?

Polycystic ovary syndrome is a hormonal disease affecting a large number of women. About 5-10% of women are affected.

This condition is characterised by an excessive secretion of androgens (such as testosterone) in the ovaries, which disrupts egg production. Instead of being released during ovulation, the eggs turn into cysts that accumulate in the ovaries. Although very variable, the main clinical symptoms noted are menstrual cycle abnormalities (absence or irregularity, which can cause infertility), heavy hair growth, acne and even alopecia. This syndrome usually occurs in adolescence. It is commonly accompanied by overweight or obesity and is associated with a number of pathologies such as type 2 diabetes, cardiovascular disease etc.

Although the mechanisms are unknown, it appears that the disease is multifactorial. It depends on genetics, lifestyle, the intrauterine environment… and on the intestinal microbiota.

Setting up a clinical trial

Professor Melanie Cree Green of the Children’s Hospital of Colorado and her team sought to identify a link between gut microbiota and the development of this disorder.

They followed 58 adolescent girls with obesity to compare differences in the composition and diversity of gut microbiota. Two groups were formed: one for girls with polycystic ovary syndrome (PCOS) and one for girls without PCOS.                         

The researchers analysed differences in gut microbiota by collecting stool samples from the participants:

  • α-diversity, indicating the diversity of a single sample. The number of species is, for example, an indicator of α-diversity;
  • β-diversity, measuring species diversity between samples.

What is the link with the intestinal microbiota?

Not surprisingly, the microbiota seems to be involved in polycystic ovary syndrome. Indeed, participants with PCOS showed significantly lower α-diversity compared to those without PCOS. Nevertheless, species richness was similar between the groups.

Another interesting result was that β-diversity differed between groups. Compared to adolescents without PCOS, those with PCOS had relative abundances:                                                                                                        

  • higher in Actinobacteria, lower in Bacteroides and similar in Firmicutes and Proteobacteria at phyla level;
  • higher in Streptococcaceae and lower in Bacteroidaceae and Porphyromonadaceae in the families;
  • a difference in Bacteroides, Prevotella, Finegoldia, Lactobacillus, Parabacteroides and Roseburia at genus level.

The bacterial profile found in the stools of adolescents with PCOS is quite different from that of girls without PCOS. It is considered to be dysbiotic, suggesting an altered gut microbiota. These ‘unhealthy’ bacteria were linked to higher concentrations of testosterone but also to markers of metabolic complications (higher blood pressure, liver inflammation and high triglycerides as examples).

Main author Prof. Melanie Cree Green concludes that the gut microbiome may play a role in this hormonal disorder and associated metabolic complications. These changes can be seen in adolescent girls in the early stages of the disease.


Further studies are needed to confirm these results and to consider new strategies, such as the use of probiotics in order to relieve this syndrome.

The intestinal microbiota seems once again to prove its great involvement in our health.



JOBIRA B, FRANK DN, PYLE L, SILVEIRA LJ, KELSEY MM, GARCIA-REYES Y, ROBERTSON CE, IR D, NADEAU KJ, CREE-GREEN M. Obese adolescents with pcos have altered biodiversity and relative abundance in gastrointestinal microbiota. J Clin Endocrinol Metab. 2020, 105(6) :e2134-2144

Picture: Freepik