Associations between Dietary Fiber, the Fecal Microbiota and Estrogen Metabolism in Postmenopausal Women with Breast Cancer

Abstract

Breast cancer is a hormonally-driven cancer, and various dietary factors are associated with estrogen metabolism, including dietary fiber. Several studies report associations between dietary fiber and breast cancer; however, research on whether fiber influences circulating estrogens through the gut microbiota is rare. The objective of this cross-sectional study among 29 newly-diagnosed (stage 0-II), post-menopausal breast cancer patients is to examine associations between dietary fiber and the gut microbiota that are linked with β-glucuronidase activity, and purportedly increase circulating estrogens. Spearman’s and partial correlations controlling for body mass index and age were performed using dietary recall data, Illumina MiSeq generated microbiota relative abundance, and HPLC-mass spectrometry-derived estradiol and estrone levels.

Major findings are: (1) total dietary fiber is inversely associated with Clostridium hathewayi (r= −0.419; p = 0.024); (2) soluble fiber is inversely associated with Clostridium (r=-0.11; p = 0.02); (3) insoluble fiber is positively associated with Bacteroides uniformis sp. (r = 0.382; p = 0.041); and (4) serum estradiol and estrone levels are not correlated with species/genera or dietary fiber, though there is a trend toward an inverse association between soluble fiber and estradiol levels (r= −0.30; p = 0.12). More studies are needed to understand the complex interaction between dietary fiber, intestinal microbiota, and hormonal levels in older females.

Authors’ Contributions

Ayse G Zengul: 1) analysis and interpretation of data (2) revising it critically for important intellectual content; (3) final approval of the version to be published; (4) Drafting the article; (5) made substantial contributions to conception and design.

Wendy Demark-Wahnefried: 1) analysis and interpretation of data (2) revising it critically for important intellectual content; (3) final approval of the version to be published.

Stephen Barnes: 1) analysis and interpretation of data (2) revising it critically for important intellectual content; (3) final approval of the version to be published; (4) acquisition of data.

Casey D. Morrow: 1) analysis and interpretation of data (2) revising it critically for important intellectual content; (3) final approval of the version to be published; (4) acquisition of data.

Brenda Bertrand: 1) analysis and interpretation of data (2) revising it critically for important intellectual content; (3) final approval of the version to be published.

Taylor F. Berryhill: 1) analysis and interpretation of data (2) revising it critically for important intellectual content; (3) final approval of the version to be published; (4) Drafting the article.

Andrew D. Fruge: 1) analysis and interpretation of data (2) revising it critically for important intellectual content; (3) final approval of the version to be published; (4) made substantial contributions to conception and design.

Conflicts of Interest

The authors declare no conflicts of interest.

Additional information

Funding

This study was supported by The National Cancer Institute R21 (CA178359), P30 (CA013148), and R25 (CA047888), UAB Cancer Research Experiences for Students (CaRES) Program, 5R25CA076023, UAB Center for Clinical Translational Science (UL1TR00065, UL1TR001417), the Heflin Center for Genomic Sciences, and the UAB Health Services Foundation General Endowment Fund (funding for the mass spectrometer used in this study). The following are acknowledged for their support of the Microbiome Resource at the University of Alabama at Birmingham: Comprehensive Cancer Center (P30AR050948), Center for Clinical Translational Science (UL1TR001417), University Wide Institutional Core, Heflin Center for Genomic Sciences and Microbiome Center.