Phytoestrogens: PLANT EXTRACTS and compounds, primarily ISOFLAVONES, that mimic or modulate endogenous estrogens, usually by binding to ESTROGEN RECEPTORS.Plant Preparations: Material prepared from plants.Isoflavones: 3-Phenylchromones. Isomeric form of FLAVONOIDS in which the benzene group is attached to the 3 position of the benzopyran ring instead of the 2 position.Estrogens, Non-Steroidal: Non-steroidal compounds with estrogenic activity.Coumestrol: A daidzein derivative occurring naturally in forage crops which has some estrogenic activity.Lignans: A class of dibenzylbutane derivatives which occurs in higher plants and in fluids (bile, serum, urine, etc.) in man and other animals. These compounds, which have a potential anti-cancer role, can be synthesized in vitro by human fecal flora. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Genistein: An isoflavonoid derived from soy products. It inhibits PROTEIN-TYROSINE KINASE and topoisomerase-II (DNA TOPOISOMERASES, TYPE II); activity and is used as an antineoplastic and antitumor agent. Experimentally, it has been shown to induce G2 PHASE arrest in human and murine cell lines and inhibits PROTEIN-TYROSINE KINASE.Equol: A non-steroidal ESTROGEN generated when soybean products are metabolized by certain bacteria in the intestines.Pueraria: A plant genus of the family FABACEAE a common weed of the southeast US. There has been folk use for alcoholism and liver protection. It contains puerarin, kakkalide, daidzein (isoflavonoids), and kudzusaponins (oleanene-type triterpene glycosides).Soybeans: An annual legume. The SEEDS of this plant are edible and used to produce a variety of SOY FOODS.Soybean Proteins: Proteins which are present in or isolated from SOYBEANS.Estrogen Receptor beta: One of the ESTROGEN RECEPTORS that has greater affinity for ISOFLAVONES than ESTROGEN RECEPTOR ALPHA does. There is great sequence homology with ER alpha in the DNA-binding domain but not in the ligand binding and hinge domains.Diet: Regular course of eating and drinking adopted by a person or animal.4-Butyrolactone: One of the FURANS with a carbonyl thereby forming a cyclic lactone. It is an endogenous compound made from gamma-aminobutyrate and is the precursor of gamma-hydroxybutyrate. It is also used as a pharmacological agent and solvent.Estrogens: Compounds that interact with ESTROGEN RECEPTORS in target tissues to bring about the effects similar to those of ESTRADIOL. Estrogens stimulate the female reproductive organs, and the development of secondary female SEX CHARACTERISTICS. Estrogenic chemicals include natural, synthetic, steroidal, or non-steroidal compounds.Receptors, Estrogen: Cytoplasmic proteins that bind estrogens and migrate to the nucleus where they regulate DNA transcription. Evaluation of the state of estrogen receptors in breast cancer patients has become clinically important.Zeranol: A non-steroidal estrogen analog.Soy Foods: Foods made from SOYBEANS. Health benefits are ascribed to the high levels of DIETARY PROTEINS and ISOFLAVONES.Quercetin: A flavonol widely distributed in plants. It is an antioxidant, like many other phenolic heterocyclic compounds. Glycosylated forms include RUTIN and quercetrin.Perissodactyla: An order of ungulates having an odd number of toes, including the horse, tapir, and rhinoceros. (Dorland, 27th ed)Estrogen Receptor alpha: One of the ESTROGEN RECEPTORS that has marked affinity for ESTRADIOL. Its expression and function differs from, and in some ways opposes, ESTROGEN RECEPTOR BETA.Soy Milk: A beverage prepared from SOYBEANS.Estradiol: The 17-beta-isomer of estradiol, an aromatized C18 steroid with hydroxyl group at 3-beta- and 17-beta-position. Estradiol-17-beta is the most potent form of mammalian estrogenic steroids.Vitex: A genus of trees in the Lamiaceae family containing assorted flavonoids with possible analgesic and antineoplastic properties. The fruit of these trees is used in herbal preparations.Estrogen Antagonists: Compounds which inhibit or antagonize the action or biosynthesis of estrogenic compounds.Hot Flashes: A sudden, temporary sensation of heat predominantly experienced by some women during MENOPAUSE. (Random House Unabridged Dictionary, 2d ed)Apigenin: 5,7,4'-trihydroxy-flavone, one of the FLAVONES.Postmenopause: The physiological period following the MENOPAUSE, the permanent cessation of the menstrual life.Flavanones: A group of FLAVONOIDS characterized with a 4-ketone.Endocrine Glands: Ductless glands that secrete HORMONES directly into the BLOOD CIRCULATION. These hormones influence the METABOLISM and other functions of cells in the body.Endocrine Disruptors: Exogenous agents, synthetic and naturally occurring, which are capable of disrupting the functions of the ENDOCRINE SYSTEM including the maintenance of HOMEOSTASIS and the regulation of developmental processes. Endocrine disruptors are compounds that can mimic HORMONES, or enhance or block the binding of hormones to their receptors, or otherwise lead to activating or inhibiting the endocrine signaling pathways and hormone metabolism.Benzoin: A white crystalline compound prepared by condensation of benzaldehyde in potassium cyanide and used in organic syntheses. This should not be confused with benzoin gum from STYRAX.Menopause: The last menstrual period. Permanent cessation of menses (MENSTRUATION) is usually defined after 6 to 12 months of AMENORRHEA in a woman over 45 years of age. In the United States, menopause generally occurs in women between 48 and 55 years of age.Flavonoids: A group of phenyl benzopyrans named for having structures like FLAVONES.Genitalia: The external and internal organs related to reproduction.Humulus: A plant genus in the CANNABACEAE family. Best known for the buds of Humulus lupulus L. used in BEER.Endocrine System: The system of glands that release their secretions (hormones) directly into the circulatory system. In addition to the ENDOCRINE GLANDS, included are the CHROMAFFIN SYSTEM and the NEUROSECRETORY SYSTEMS.Estrogen Replacement Therapy: The use of hormonal agents with estrogen-like activity in postmenopausal or other estrogen-deficient women to alleviate effects of hormone deficiency, such as vasomotor symptoms, DYSPAREUNIA, and progressive development of OSTEOPOROSIS. This may also include the use of progestational agents in combination therapy.Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Flax: A plant genus of the family LINACEAE that is cultivated for its fiber (manufactured into linen cloth). It contains a trypsin inhibitor and the seed is the source of LINSEED OIL.Breast Neoplasms: Tumors or cancer of the human BREAST.Ovariectomy: The surgical removal of one or both ovaries.Phenols: Benzene derivatives that include one or more hydroxyl groups attached to the ring structure.Chromans: Benzopyrans saturated in the 2 and 3 positions.