ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2019) 63 P1145 | DOI: 10.1530/endoabs.63.P1145

Prevalence of equol production capacity in women with polycystic ovary syndrome (PCOS) and association with reproductive, hormonal and metagenomic parameters before and 3 days after isoflavone challenge

Lisa Lindheim1, Christoph Haudum1,2, Angelo Ascani1, Christian Trummer1, Julia Münzker3, Angela Horvath4 & Barbara Obermayer-Pietsch1,2


1Department of Internal Medicine, Division of Endocrinology and Diabetology, Medical University Graz, Graz, Austria; 2Center for Biomarker Research in Medicine (CBmed), Graz, Austria; 3Department of Medicine, Integrated Research and Treatment Centre for Adiposity Diseases, University of Leipzig, Leipzig, Germany; 4Department of Internal Medicine, Division of Gastroenterology and Hepatology, Medical University Graz, Graz, Austria.


Objective: Polycystic ovary syndrome (PCOS) is characterized by biochemical and clinical androgen excess and disturbed ovarian function and is associated with disorders of glucose and lipid metabolism. Isoflavones are phytoestrogens exerting endocrine effects on human hormone and metabolic signaling and may influence symptom penetrance in PCOS. We investigated whether women with PCOS and healthy controls have alterations in their capacity to metabolize hormonally active dietary isoflavones to produce the metabolite equol and whether this capacity is associated with PCOS-typical clinical, biochemical and metagenomic pathways.

Methods: Urine isoflavone and equol levels were measured by mass spectrometry in women with PCOS (n=24) and non-PCOS controls (n=20) before and after 3 days of soy challenge. Bacterial equol production was evaluated using the log(equol: daidzein ratio). Group size was calculated according to the effect of equol. Metagenome analyses were performed using PiCRUST (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States), LEfSe (Linear discriminant analysis effect size) and QIIME1.9 (Quantitative Insights Into Microbial Ecology).

Results: The prevalence of equol producers was 21% in the PCOS group and 42% in controls; however, this difference was not statistically significant due to the pilot study sample size. In the whole cohort, larger equol production was associated with lower serum total and free testosterone, androstenedione and anti-Müllerian hormone (AMH) levels, but only AMH remained significant in both groups separately. After isoflavone challenge, stool metagenome pathway groups primarily associated with PCOS phenotypes aligned with the pattern of the control group.

Summary and Conclusions: We conclude that a reduced capacity to produce equol is likely not a driving factor in the pathophysiology of PCOS but might rather modulate several aspects of PCOS. These women might therefore benefit from consuming isoflavone-rich foods, as their stool metagenome findings shifted to the control pattern after isoflavone ingestion.