URINARY LIGNAN AND ISOFLAVONOID EXCRETION IN PREMENOPAUSAL WOMEN CONSUMING FLAXSEED POWDER

Lignans and isoflavonoid phytoestrogens, produced from plant precursor s by colonic bacteria, may protect against certain cancers. We examine d the effects of flaxseed consumption on urinary lignans and isoflavon oids. Eighteen women consumed their usual omnivorous diets for three m enstrual cycles and their usual diets supplemented with flaxseed powde r (10 g/d) for three cycles in a randomized crossover design. Three-da y urine samples from follicular and luteal phases were analyzed for li gnans and isoflavonoids by isotope-dilution gas chromatography-mass sp ectrometry. Excretion of the lignans enterodiol and enterolactone incr eased with flaxseed from 1.09 +/- 1.08 and 3.16 +/- 1.47 to 19.48 +/- 1.10 and 27.79 +/- 1.50 mu mol/d, respectively (P < 0.0002). Enterodio l and enterolactone excretion varied among subjects in response to fla xseed (3- to 285-fold increase). There were no differences in excretio n of isoflavonoids (daidzein, genistein, equol, and O-desmethylangofen sin) or the lignan matairesinol with flaxseed. Excretion was not alter ed by phase of menstrual cycle or duration of flaxseed consumption.