Anti-estrogen substances block the effects of the sex hormone estrogen, a natural steroid hormone primarily responsible for regulation of the female reproductive cycle. Strategies to lower estrogen levels with aromatase inhibitors and block estrogen’s actions with anti-estrogen substances are used to correct estrogen dominance, an imbalance in the sex hormones. Aromatase inhibitors work to block the production of estrogens from androgens in post-menopausal women and in men. Anti-estrogen compounds bind to estrogen receptors in the cells to prevent estrogen from activating the receptors.
It is believed that dietary sources of plant estrogens and hormone-mimicking chemicals in the environment contribute to estrogen dominance. Eating excessive meat and dairy products from animals treated with hormones may cause hormone imbalances. Some plants and herbs, including soy, are sources of non-steroidal plant estrogens that may also raise estrogen levels. In addition, hormone-mimicking chemicals that act as estrogens are prevalent in the environment. They originate from plastics, agricultural chemicals, cosmetics and household products.
Anti-estrogens are thought to counter the effects of excess exposure to dietary and environmental sources of estrogens. Too much estrogen has been linked to atherosclerosis in older women, early onset of puberty in children, and the development of hormone-sensitive cancers. An excess of estrogen may also be responsible for the rise in obesity rates. It is believed that estrogen dominance causes the development of many chronic conditions including declining male fertility. Anti-estrogens are used to balance the effects of excess estrogen.
In some countries, anti-estrogen products are available by prescription, while in others they are sold as over-the-counter dietary supplements. They are available both by prescription and over-the-counter in certain countries. Body builders often use anti-estrogen supplements and aromatase inhibitors to improve their muscle development and reduce side effects from steroids. Tamoxifen is a prescription anti-estrogen medication used to treat estrogen-sensitive breast cancer in pre-menopausal women. It binds to the cancer cells' estrogen receptors without activating them.
Aromatase inhibitors are used to treat post-menopausal women with hormone-sensitive breast cancer. It is thought that 80 percent of breast cancers rely on estrogen to grow. In post-menopausal women, estrogen is produced from androgen in fatty tissues including in the breast. By suppressing the production of estrogen, the supply to the cancer cells is reduced.
Estrogen dominance can also be managed by dietary means. Specific foods that are high in estrogen are avoided, while others that are estrogen antagonists are emphasized. The anti-estrogen diet eliminates conventionally produced meat and dairy products along with fruits and vegetables with high pesticide residues. Consumption of organic foods including fresh vegetables, fruits and organic animal products is recommended. Foods that show a marked anti-estrogen action include the common button mushroom, cruciferous vegetables and green tea.
