Some herbs contain estrogen-like substances called phytoestrogens. Marketed to relieve the symptoms of menopause, they may help some women, but medical evidence does not consistently support these claims. Phytoestrogens may have side effects. They may also stimulate the growth of estrogen-related cancers. Always talk to your health care provider before using herbs containing phytoestrogens.
Definition
Phytoestrogens are substances found in plants that are similar in structure to the hormone estrogen. Different types of phytoestrogens, such as isoflavones, coumestans and lignans, are not the same. They all resemble estrogen but they act in different ways. Some mimic the effect of natural estrogen in the body, while others block estrogen's ability to function, notes Cornell University.
Red Clover
Red clover, also called cow clover and meadow clover, is a perennial herb that contains several isoflavones and is used to relieve hot flashes caused by menopause, according to Memorial Sloan-Kettering. The phytoestrogens in red clover may have a harmful effect on hormone-sensitive cancers and medical conditions. Some isoflavones in red clover may reduce the risk of osteoporosis and cardiovascular disease. Red clover also contains a non-estrogen compound called coumarin, which interacts with anticoagulant medications and may increase the risk of bleeding.
Black Cohosh
Native to North America, black cohosh grows in wooded areas and has roots and rhizomes that have been used in traditional medicine to treat pain and reduce inflammation. Now this herb is used primarily to treat symptoms of menopause. The University of Maryland Medical Center notes that it helps relieve hot flashes, but its effects are not consistent for all women. Black cohosh may protect against breast cancer, or it may stimulate its growth. It may also protect against age-related bone loss. The full biological impact of this herb is still being researched as of June 2011. Black cohosh may cause side effects such as stomach upset, rashes, dizziness and headaches. Be aware that it has been reported to have a toxic effect on the liver. If you take black cohosh and develop abdominal pain, dark urine or jaundice, consult a physician.
Dong Quai
A Chinese herb that's promoted to relieve menstrual and menopausal symptoms, dong quai has not been proven to contain phytoestrogens, according to the Mayo Clinic. However, an extract from dong quai stimulated estrogen receptors that had both a positive and negative effect on breast cancer cells, notes Memorial Sloan-Kettering. Side effects may include bloating, loss of appetite, diarrhea, photosensitivity or gynecomastia. This herb should be avoided by women who are pregnant, breastfeeding or have hormone-sensitive cancers, and by anyone taking anticoagulant medications.
