(HealthDay News) — Diversity of fecal microbiome is associated with an increased ratio of hydroxylated estrogen metabolites to parent estrogen, according to a study published in the Journal of Clinical Endocrinology & Metabolism.

Barbara J. Fuhrman, PhD, from the University of Arkansas for Medical Sciences in Little Rock, and colleagues examined whether urinary estrogens and estrogen metabolites correlate with the diversity and composition of the fecal microbiome. 

Data were collected from 60 women drawn from a sample of healthy postmenopausal women aged 55 to 69 years without current or recent use of antibiotics or hormone therapy and without history of cancer or gastrointestinal disease. 

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The correlations between diversity and composition of the fecal microbiome and parent estrogen, total estrogens, estrogen metabolites and the ratio of estrogen metabolites and parent estrogen, which has been associated with postmenopausal breast cancer, were assessed.

The researchers found that there was a direct correlation between the ratio of metabolites to parents and whole-tree phylogenetic diversity (P=.01). Correlations were also seen for the relative abundance of the order Clostridiales and the genus Bacteroides and the ratio of metabolites to parents. 

The correlations were found to be independent of age, BMI and study design

“Our data suggest that women with a more diverse gut microbiome exhibit an elevated urinary ratio of hydroxylated estrogen metabolites to parent estrogen,” the researchers wrote.


  1. Fuhrman BJ et al. J Clin Endocrinol Metab. 2014;doi:10.1210/jc.2014-2222.