Gut reaction: Could hormone receptors on gut bacteria be driving diet-health interactions?
The study investigated diet complexity and estrogen hormone receptors on intestinal microbiota ecology by assessing whether alterations in isoflavone intake lcomposition of the microbiota.
Led by Joseph Sturino from Texas A&M University, the research team noted that some steroid hormones, like estradiol, and dietary phytoestrogens (such as isoflavones) are known to influence the development of chronic gastrointestinal inflammation and estrogen-responsive cancers of the breast, prostate and colon.
"In this study, we wanted to determine if steroid hormone nuclear receptors, specifically estrogen receptor beta, affect the composition of intestinal bacteria," he explained.
"As you might expect, significant differences were found between the fecal microorganisms of mice fed a biochemically complex diet containing isoflavones and those that were fed a simple diet that lacked isoflavones," said Sturino. "Interestingly, however, we also found that the microorganisms differed between mice that expressed estrogen receptor beta and those that did not."
Diet, hormones, and the microbiota
In order to investigate the effects of both receptors and diet on intestinal microorganisms, the scientists initially raised female mice on a fibre-rich diet containing isoflavones (a complex diet). The animals were then fed an isoflavone-free diet that was rich in highly refined sugars for two weeks (a simple diet). The composition of the fecal bacteria was surveyed over the course of the study.
Distinct patterns for Lactobacillales found exclusive for and highly abundant among mice fed the complex diet containing isoflavones, explained Sturino.
In contrast, he noted, that the relative diversity of Proteobacteria increased significantly following the transition to the simple, isoflavone-free diet. Proteobacteria includes a number of species commonly associated with intestinal disease, including Escherichia and salmonella.
"While the balance and content of microorganisms in the gut changes as we age, we are only now learning how our genetics and dietary choices affect our health by modifying the composition and activity of these microorganisms," he said.
In the long term, Sturino said that he believes that this study will aid in the development of novel probiotics, prebiotics, nutritional strategies and pharmaceuticals to improve overall health by promoting the growth and activity of beneficial intestinal microorganisms.