A new study suggests that women in post menopause with a population more diverse intestinal bacteria may be more efficient in bring down the estrogen. Sinceé oestrogens play a role in causing breast cancer, researchers speculate that a bacterial population healthy may lower the risk of cancer.
“The composition and diversityà microbioti intestinal were associated with the pathways of metabolism of estrogen that are predictive of the risk of breast cancer in women post menopause,” notes Barbara J. Fuhrman, physician in the Department of Epidemiology, Fay W. Boozman College of Public Health, Università of the state of Arkansas for the Medical Sciences, Little Rock, and colleagues in an article published online September 11 in the Journal of Endocrinology Clinical and Metabolism.
estrogen is metabolized in the liver and in other tissues such as the breast, producing fragments that are secreted in the urine or via the bile, into the intestine. The microbes of the intestine can degrade these metabolites, allowing them to be reabsorbed into the blood stream and further recycled in the liver. Dr. Fuhrman and colleagues suggest that women whose gut bacteria process l’estrogen più effectively could have a reduced risk for breast cancer.
The study involved 60 women post menopause who were members of Kaiser Permanente Colorado. Their age ranged from 55 to 70 years, 91% were white and the average body mass index of the subjects was 27 Kg/m2. All had a normal mammogram within the 8 weeks previous. Women gave fecal samples to check for diversityà bacterial, così as the urine samples to examine the relationship between estrogens and estrogen metabolites.
The patients with più diversityà of microbes in the fecal samples had ratios più high of the metabolites compared to the estrogen progenitor (P for trend = .004). However, the association was true for 1 of the 3 measurements of diversityà used, such as a set of three diversityà, phylogenetic, and not for the 2 common ways to measure the diversityà bacterial, indices of Simpson and Shannon.
bacteria of the class Clostridia, especially the gene Ruminococcus, were significantly associated with high ratios of metabolites (P=.04), and those of the gene of Bacteroides were inversely related (P=.03), although these P-values – were not adjusted for multiple comparisons, and the authors write that these associations “should be considered as esploratorie.”
Given that the study relied on sequencing the 16S ribosome RNA, rather than on sequencing the genome-the entire or a functional analysis, researchers have not been able to determine how or if the microbes are responsible for the differences seen in the estrogen metabolites. They write that their findings “provide a first step towards the ultimate goal of understanding how the microbioti bowel may affect the homeostasis of hormones and its impact on human health.”
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