Effect of Flaxseed and Wheat Bran on Serum Hormones and Lignan Excretion in Premenopausal Women.

Key Findings

The purpose of this study was to investigate the effects of flaxseed consumption alone and in combination with wheat bran on serum sex hormone and binding protein concentrations and urinary lignan excretion in premenopausal women.  Both phytoestrogens and dietary fiber have been shown to have cancer protective effects, but dietary fiber may change phytoestrogen metabolism in the large intestine, potentially changing their biological effects. The results showed that flaxseed significantly increases urinary excretion of lignans without changing the serum hormone concentrations in this group of premenopausal women. This suggests that the chemoprotective effects reported for flaxseed may result from a mechanism other than a hormonal effect. Wheat bran had no effect on either urinary lignan excretion or serum hormone concentrations.

ABSTRACT

Objective: To examine the effects of flaxseed consumption (a lignan-rich plant food) alone and in combination with wheat bran on serum hormones and urinary lignan excretion in premenopausal women. Methods: Sixteen subjects were studied for four feeding treatments lasting two menstrual cycles each in a randomized, crossover design. During each treatment, subjects consumed their habitual diets supplemented with baked goods containing no flaxseed or wheat bran, 10 g of flaxseed, 28 g of wheat bran, or 10 g of flaxseed plus 28 g of wheat bran/day. Serum samples collected during the mid-luteal phase of the second menstrual cycle of each diet treatment were analyzed for serum hormones and sex hormone binding globulin. Urine samples collected during the same time period were analyzed for urinary lignan excretion.

Results: There were no changes in serum hormone concentrations or sex hormone binding globulin on any of the treatments. Urinary lignan excretion significantly increased on diet treatments that included flaxseed, but inclusion of wheat bran did not significantly alter lignan excretion. Conclusions: Urinary lignan excretion increased with flaxseed consumption, but serum hormones did not change in this group of premenopausal women. Consumption of wheat bran with flaxseed did not alter urinary lignan excretion associated with flaxseed consumption.