Effect of Flax Seed Ingestion on the Menstrual Cycle
Phipps, W.R., Martini, M.C., Lampe, J.W., Slavin, J.L., and Kurzer, M.S. 1993. 77:1215-1219.
This study examines the effect of dietary supplementation of flax seed powder on the menstrual cycle in 18 women with normal menstrual cycles. Women consumed the habitual diet for 3 cycles, followed by habitual diet supplemented with flax seed. The second and third months were compared in the two groups. Although three anovulatory cycles occurred during the 36 control cycles, none occurred during the 36 flax seed cycles. In the flax seed treated cycles, the luteal phase of the ovulatory cycle was longer, although no significant difference between estradiol or estrone during the early follicular phase, or midfollicular phase occurred. Higher progesterone/estradiol ratios during the luteal phase and higher testosterone during midfollicular phase occurred in the flax treated cycles. Flax seed ingestion had no effect on sex hormone binding globulin (SHBG), which contrasted earlier studies, but this may be due to the shorter duration of the study, or to other effects. The changes that occurred during flax seed supplementation are consistent with a decreased tendency to ovarian dysfunction, which has been associated positively with an increased risk of breast cancer. The effects of lignans observed in this study may be similar to those of tamoxifen, a structurally similar compound that is a possible preventive agent against breast cancer. The authors conclude that the effects of dietary supplementation with flax seed on the menstrual cycle suggest a role for lignans in the relationship between diet and sex steroid action and possibly between diet and hormonally dependent cancer.