Dietary Fiber Intake and Endogenous Serum Hormone Levels in Naturally Postmenopausal Mexican American Women: The Multiethnic Cohort Study

Abstract

This study investigated dietary fiber intake in association with serum estrogen levels in naturally postmenopausal Latina women with a wide range of fiber intake. Estrone (E₁), estradiol (E₂), and sex-hormone-binding globulin (SHBG) were measured in 242 women. Associations between estrogen levels and intake of dietary fiber, including insoluble and soluble fractions, quantified from a food frequency questionnaire, were examined. The biomarker enterolactone was also measured. After adjustment for age, weight, and other nondietary factors, dietary fiber intake was inversely associated with E₁ and E₂; there was a 22% and 17% decrease (2P _trend = 0.023 and 0.045) among subjects in the highest quintile of intake compared with the lowest. Fitting dietary fiber together with soluble and insoluble nonstarch polysaccharides (NSP) showed a much greater decrease in E₁ and E₂ (47% and 41%, respectively) while increased soluble NSP intake showed increases in E₁ and E₂ (64% and 69%, respectively). Two foods, avocado and grapefruit, showed significant positive associations with E ₁ (2P _trend = 0.029 and 0.015, respectively). This study suggests that different components of dietary fiber may have very significant different effects on serum estrogen levels. The suggestive findings relating increased estrogen levels to avocado and grapefruit intakes need confirmation.

Acknowledgments and Notes

This work was supported in part by a grant from the California Breast Cancer Research Program (8WB-0066), and grants from the National Cancer Institute (CA063464 and CA54281). We thank Elisabet Gentzschein for performing the hormone assays; Adile Samaletdin for performing the enterolactone assay; and Marina Herrera, Maria Salazar, and Norma Torres for administrative assistance. We also sincerely thank the women who participated in the study.

Notes

^a Mean ± SD based on FFQ filled out concurrent with blood draw.

^b All nutrient intakes are given as grams per 1,000 kcal. Abbreviations are as follows: NSP, nonstarch polysaccharides; BMI, body mass index; FFQ, food frequency questionnaire.

^a Abbreviations are as follows: E₁, estrone; E₂, estradiol; SHBG, sex-hormone-binding globulin.

^a Adjusted for age at blood draw, years since natural menopause, weight, birthplace, current smoking status, and ethanol intake. Abbreviations are as follows: E₁, estrone; E₂, estradiol; NSP, nonstarch polysaccharides; Q, quintile.

^b Dietary fiber, soluble NSP, and insoluble NSP are simultaneously adjusted for the other 2 components.

^c Median intake within quintile (in parenthesis) used for test of linear trend.

^a Adjusted for age at blood draw, years since natural menopause, weight, birthplace, current smoking status, and ethanol intake. Abbreviations are as follows: E₁, estrone; E₂, estradiol; NSP, nonstarch polysaccharides; Q, quintile.

^b Each fat component is simultaneously adjusted for the other 2 components.

^c Median intake within quintile (in parenthesis) used for test of linear trend.

^a Adjusted for age at blood draw, years since natural menopause, weight, birthplace, current smoking, and ethanol intake. Abbreviations are as follows: E₁, estrone; E₂, estradiol; Q, quintile; NSP, nonstarch polysaccharides.

^b Further adjusted for total dietary fiber and soluble NSP intakes. Avocado also adjusted for monounsaturated fat intake

^c Median intake within subgroup (in parenthesis) used for test of linear trend.

^a Adjusted for time interval between last meal and blood draw, age at blood draw, years since natural menopause, birthplace, weight, current smoking status, and ethanol. SHBG further adjusted for height. Abbreviations are as follows: E₁, estrone; E₂, estradiol; SHBG, sex-hormone-binding globulin; Q, quintile.