A recent study out of the University of Maryland suggests that post-menopausal women with a more diverse microbiome have a lower risk of getting breast cancer. The study investigated the fecal microbiomes of 60 healthy women between the ages of 55 and 69 while also testing the estrogen and estrogen metabolites from their urine. The results showed a correlation between increased urinary metabolites with increased gut microbiome diversity, independent of other variables.
This is important because estrogen that circulates through the body, that isn't broken down and removed by the body, is correlated with an increased risk for breast cancer. Therefore, decreasing the amount of circulating estrogen, and increasing the rate at which estrogen is removed from the body may result in a lower risk of breast cancer for post-menopausal women.
It is known that as estrogen and its byproducts are naturally processed, they are circulated in and around the gut, which has led scientists to speculate that the gut microbiome may be important to estrogen cycling and removal in the body. The authors of this paper help support this hypothesis by showing that microbiome diversity effects estrogen removal.
This paper opens the door to some very interesting questions. Can microbiome diversity be used as a diagnostic for breast cancer risk? Can the gut microbiome be adjusted to decrease breast cancer risk? A nice summary of the findings with quotes from the authors was also published by Science Daily.