Flaxseed Influences Urinary Lignan Excretion in a Dose-dependent Manner in Postmenopausal Women1
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota 55108 [A. M. H., M. C. M., J. L. S.]; Department of Nutrition, College of St. Benedict, St. Joseph, Minnesota 56374 [B. A. O.]; and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, Minnesota 55455 [W. T.]
Abstract
Dietary estrogens, such as lignans, are similar in structure to endogenous sex steroid hormones and may act in vivo to alter hormone metabolism and subsequent cancer risk. The objective of this study was to examine the effect of dietary intake of a lignan-rich plant food (flaxseed) on urinary lignan excretion in postmenopausal women. This randomized, cross-over trial consisted of three 7-week feeding periods during which 31 healthy postmenopausal women, ages 52–82 years, consumed their habitual diets plus 0, 5, or 10 grams of ground flaxseed per day. Urine samples collected for 2 consecutive days during the last week of each feeding period were analyzed for lignan content (enterodiol, enterolactone, and matairesinol) by isotope dilution gas chromatography/mass spectrometry. Compared with the 0-gram flaxseed diet, consumption of 5 or 10 grams of flaxseed significantly increased excretion of enterodiol by 1,009 and 2,867 nmol/day, respectively; significantly increased excretion of enterolactone by 21,242 and 52,826 nmol/day, respectively; and significantly increased excretion of total lignans (enterodiol + enterolactone + matairesinol) by 24,333 and 60,640 nmol/day, respectively. Excretion of matairesinol was not significantly altered by flaxseed consumption. Consumption of flax, a significant source of dietary estrogens, in addition to their habitual diets increased excretion of enterodiol and enterolactone, but not matairesinol, in a dose-dependent manner in this group of postmenopausal women. Urinary excretion of lignan metabolites is a dose-dependent biomarker of flaxseed intake within the context of a habitual diet.
Footnotes
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The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 Supported by NIH National Cancer Institute Grant R01CA-66675-01 and by the 1998 Jean Hankin Nutritional Epidemiology Award from the American Dietetic Association Foundation.
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↵2 Present address: Kraft Foods, 801 Waukegan Road, Glenview, IL 60025.
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↵3 To whom requests for reprints should be addressed, at Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Avenue, St. Paul, MN 55108-6099.
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↵4 The abbreviations used are: BMI, body mass index; CV, coefficient of variation.
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- Accepted August 14, 1900.
- Received December 28, 1999.
- Revision received August 9, 1900.
