Breast cancer is hormone-sensitive, meaning that in the early stages, tumor growth is influenced by the sex hormones, particularly estrogen and its metabolites. The biologically active form of estrogen is estradiol, which is oxidized mainly in the liver to estrone. Estrone can be converted to two metabolites with different biologic effects- 2-hydroxyestrone has little biologic activity, while 16∝-hydroxyestrone enhances estrogen activity and promotes uncontrollable tumor cell growth or cell proliferation, as it is called. Women who produce more 16∝-hydroxyestrone may have an increased risk of breast cancer. Two clinical studies found postmenopausal women who ate a diet supplemented with 10g or 25g of milled flax for 7 weeks or 16 weeks2 increased the excretion of 2-hydroxyestrone in their urine, without increasing the excretion of 16∝-hydroxyestrone. In these studies, flax consumption shifted the balance toward production of the relatively inactive metabolite of estrogen, thus supporting a role for flax seed in breast cancer prevention.

Dr. Diane H. Morris