Phytoestrogen

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A phytoestrogen is a plant-derived xenoestrogen (a type of estrogen produced by organisms other than humans) not generated within the endocrine system, but consumed by eating plants or manufactured foods. [1] Also called a "dietary estrogen", it is a diverse group of naturally occurring nonsteroidal plant compounds that, because of its structural similarity to estradiol (17-β-estradiol), have the ability to cause estrogenic or antiestrogenic effects. [2] Phytoestrogens are not essential nutrients because their absence from the diet does not cause a disease, nor are they known to participate in any normal biological function. [2] Common foods containing phytoestrogens are soy protein, beans, oats, barley, rice, coffee, apples, carrots (see Food Sources section below for bigger list).

Contents

Its name comes from the Greek phyto ("plant") and estrogen, the hormone which gives fertility to female mammals. The word "estrus" (Greek οίστρος) means "sexual desire", and "gene" (Greek γόνο) is "to generate". It has been hypothesized that plants use a phytoestrogen as part of their natural defense against the overpopulation of herbivore animals by controlling female fertility. [3] [4]

The similarities, at molecular level, of an estrogen and a phytoestrogen allow them to mildly mimic and sometimes act as an antagonist of estrogen. [2] Phytoestrogens were first observed in 1926, [2] [5] but it was unknown if they could have any effect in human or animal metabolism. In the 1940s and early 1950s, it was noticed that some pastures of subterranean clover and red clover (phytoestrogen-rich plants) had adverse effects on the fecundity of grazing sheep. [2] [6] [7] [8]

Chemical structures of the most common phytoestrogens found in plants (top and middle) compared with estrogen (bottom) found in animals Phytoestrogens2.png
Chemical structures of the most common phytoestrogens found in plants (top and middle) compared with estrogen (bottom) found in animals

Structure

Phytoestrogens mainly belong to a large group of substituted natural phenolic compounds: the coumestans, prenylflavonoids and isoflavones are three of the most active in estrogenic effects in this class. [1] The best-researched are isoflavones, which are commonly found in soy and red clover. Lignans have also been identified as phytoestrogens, although they are not flavonoids. [2] Mycoestrogens have similar structures and effects, but are not components of plants; these are mold metabolites of Fusarium , especially common on cereal grains, [9] [10] [11] but also occurring elsewhere, e.g. on various forages. [12] Although mycoestrogens are rarely taken into account in discussions about phytoestrogens, these are the compounds that initially generated the interest on the topic. [13]

Mechanism of action

Phytoestrogens exert their effects primarily through binding to estrogen receptors (ER). [14] There are two variants of the estrogen receptor, alpha (ER-α) and beta (ER-β) and many phytoestrogens display somewhat higher affinity for ER-β compared to ER-α. [14]

The key structural elements that enable phytoestrogens to bind with high affinity to estrogen receptors and display estradiol-like effects are: [2]

In addition to interaction with ERs, phytoestrogens may also modulate the concentration of endogenous estrogens by binding or inactivating some enzymes, and may affect the bioavailability of sex hormones by depressing or stimulating the synthesis of sex hormone-binding globulin (SHBG). [8]

Emerging evidence shows that some phytoestrogens bind to and transactivate peroxisome proliferator-activated receptors (PPARs). [15] [16] In vitro studies show an activation of PPARs at concentrations above 1 μM, which is higher than the activation level of ERs. [17] [18] At the concentration below 1 μM, activation of ERs may play a dominant role. At higher concentrations (>1 μM), both ERs and PPARs are activated. Studies have shown that both ERs and PPARs influence each other and therefore induce differential effects in a dose-dependent way. The final biological effects of genistein are determined by the balance among these pleiotrophic actions. [15] [16] [17]

Affinities of estrogen receptor ligands for the ERα and ERβ
Ligand Other names Relative binding affinities (RBA, %)a Absolute binding affinities (Ki, nM)aAction
ERα ERβ ERα ERβ
Estradiol E2; 17β-Estradiol1001000.115 (0.04–0.24)0.15 (0.10–2.08)Estrogen
Estrone E1; 17-Ketoestradiol16.39 (0.7–60)6.5 (1.36–52)0.445 (0.3–1.01)1.75 (0.35–9.24)Estrogen
Estriol E3; 16α-OH-17β-E212.65 (4.03–56)26 (14.0–44.6)0.45 (0.35–1.4)0.7 (0.63–0.7)Estrogen
Estetrol E4; 15α,16α-Di-OH-17β-E24.03.04.919Estrogen
Alfatradiol 17α-Estradiol20.5 (7–80.1)8.195 (2–42)0.2–0.520.43–1.2Metabolite
16-Epiestriol 16β-Hydroxy-17β-estradiol7.795 (4.94–63)50 ? ?Metabolite
17-Epiestriol 16α-Hydroxy-17α-estradiol55.45 (29–103)79–80 ? ?Metabolite
16,17-Epiestriol 16β-Hydroxy-17α-estradiol1.013 ? ?Metabolite
2-Hydroxyestradiol 2-OH-E222 (7–81)11–352.51.3Metabolite
2-Methoxyestradiol 2-MeO-E20.0027–2.01.0 ? ?Metabolite
4-Hydroxyestradiol 4-OH-E213 (8–70)7–561.01.9Metabolite
4-Methoxyestradiol 4-MeO-E22.01.0 ? ?Metabolite
2-Hydroxyestrone 2-OH-E12.0–4.00.2–0.4 ? ?Metabolite
2-Methoxyestrone 2-MeO-E1<0.001–<1<1 ? ?Metabolite
4-Hydroxyestrone 4-OH-E11.0–2.01.0 ? ?Metabolite
4-Methoxyestrone 4-MeO-E1<1<1 ? ?Metabolite
16α-Hydroxyestrone 16α-OH-E1; 17-Ketoestriol2.0–6.535 ? ?Metabolite
2-Hydroxyestriol 2-OH-E32.01.0 ? ?Metabolite
4-Methoxyestriol 4-MeO-E31.01.0 ? ?Metabolite
Estradiol sulfate E2S; Estradiol 3-sulfate<1<1 ? ?Metabolite
Estradiol disulfate Estradiol 3,17β-disulfate0.0004 ? ? ?Metabolite
Estradiol 3-glucuronide E2-3G0.0079 ? ? ?Metabolite
Estradiol 17β-glucuronide E2-17G0.0015 ? ? ?Metabolite
Estradiol 3-gluc. 17β-sulfate E2-3G-17S0.0001 ? ? ?Metabolite
Estrone sulfate E1S; Estrone 3-sulfate<1<1>10>10Metabolite
Estradiol benzoate EB; Estradiol 3-benzoate10 ? ? ?Estrogen
Estradiol 17β-benzoate E2-17B11.332.6 ? ?Estrogen
Estrone methyl ether Estrone 3-methyl ether0.145 ? ? ?Estrogen
ent-Estradiol 1-Estradiol1.31–12.349.44–80.07 ? ?Estrogen
Equilin 7-Dehydroestrone13 (4.0–28.9)13.0–490.790.36Estrogen
Equilenin 6,8-Didehydroestrone2.0–157.0–200.640.62Estrogen
17β-Dihydroequilin 7-Dehydro-17β-estradiol7.9–1137.9–1080.090.17Estrogen
17α-Dihydroequilin 7-Dehydro-17α-estradiol18.6 (18–41)14–320.240.57Estrogen
17β-Dihydroequilenin 6,8-Didehydro-17β-estradiol35–6890–1000.150.20Estrogen
17α-Dihydroequilenin 6,8-Didehydro-17α-estradiol20490.500.37Estrogen
Δ8-Estradiol 8,9-Dehydro-17β-estradiol68720.150.25Estrogen
Δ8-Estrone 8,9-Dehydroestrone19320.520.57Estrogen
Ethinylestradiol EE; 17α-Ethynyl-17β-E2120.9 (68.8–480)44.4 (2.0–144)0.02–0.050.29–0.81Estrogen
Mestranol EE 3-methyl ether ?2.5 ? ?Estrogen
Moxestrol RU-2858; 11β-Methoxy-EE35–435–200.52.6Estrogen
Methylestradiol 17α-Methyl-17β-estradiol7044 ? ?Estrogen
Diethylstilbestrol DES; Stilbestrol129.5 (89.1–468)219.63 (61.2–295)0.040.05Estrogen
Hexestrol Dihydrodiethylstilbestrol153.6 (31–302)60–2340.060.06Estrogen
Dienestrol Dehydrostilbestrol37 (20.4–223)56–4040.050.03Estrogen
Benzestrol (B2) –114 ? ? ?Estrogen
Chlorotrianisene TACE1.74 ?15.30 ?Estrogen
Triphenylethylene TPE0.074 ? ? ?Estrogen
Triphenylbromoethylene TPBE2.69 ? ? ?Estrogen
Tamoxifen ICI-46,4743 (0.1–47)3.33 (0.28–6)3.4–9.692.5SERM
Afimoxifene 4-Hydroxytamoxifen; 4-OHT100.1 (1.7–257)10 (0.98–339)2.3 (0.1–3.61)0.04–4.8SERM
Toremifene 4-Chlorotamoxifen; 4-CT ? ?7.14–20.315.4SERM
Clomifene MRL-4125 (19.2–37.2)120.91.2SERM
Cyclofenil F-6066; Sexovid151–152243 ? ?SERM
Nafoxidine U-11,000A30.9–44160.30.8SERM
Raloxifene –41.2 (7.8–69)5.34 (0.54–16)0.188–0.5220.2SERM
Arzoxifene LY-353,381 ? ?0.179 ?SERM
Lasofoxifene CP-336,15610.2–16619.00.229 ?SERM
Ormeloxifene Centchroman ? ?0.313 ?SERM
Levormeloxifene 6720-CDRI; NNC-460,0201.551.88 ? ?SERM
Ospemifene Deaminohydroxytoremifene0.82–2.630.59–1.22 ? ?SERM
Bazedoxifene – ? ?0.053 ?SERM
Etacstil GW-56384.3011.5 ? ?SERM
ICI-164,384 –63.5 (3.70–97.7)1660.20.08Antiestrogen
Fulvestrant ICI-182,78043.5 (9.4–325)21.65 (2.05–40.5)0.421.3Antiestrogen
Propylpyrazoletriol PPT49 (10.0–89.1)0.120.4092.8ERα agonist
16α-LE2 16α-Lactone-17β-estradiol14.6–570.0890.27131ERα agonist
16α-Iodo-E2 16α-Iodo-17β-estradiol30.22.30 ? ?ERα agonist
Methylpiperidinopyrazole MPP110.05 ? ?ERα antagonist
Diarylpropionitrile DPN0.12–0.256.6–1832.41.7ERβ agonist
8β-VE2 8β-Vinyl-17β-estradiol0.3522.0–8312.90.50ERβ agonist
Prinaberel ERB-041; WAY-202,0410.2767–72 ? ?ERβ agonist
ERB-196 WAY-202,196 ?180 ? ?ERβ agonist
Erteberel SERBA-1; LY-500,307 ? ?2.680.19ERβ agonist
SERBA-2 – ? ?14.51.54ERβ agonist
Coumestrol –9.225 (0.0117–94)64.125 (0.41–185)0.14–80.00.07–27.0Xenoestrogen
Genistein –0.445 (0.0012–16)33.42 (0.86–87)2.6–1260.3–12.8Xenoestrogen
Equol –0.2–0.2870.85 (0.10–2.85) ? ?Xenoestrogen
Daidzein –0.07 (0.0018–9.3)0.7865 (0.04–17.1)2.085.3Xenoestrogen
Biochanin A –0.04 (0.022–0.15)0.6225 (0.010–1.2)1748.9Xenoestrogen
Kaempferol –0.07 (0.029–0.10)2.2 (0.002–3.00) ? ?Xenoestrogen
Naringenin –0.0054 (<0.001–0.01)0.15 (0.11–0.33) ? ?Xenoestrogen
8-Prenylnaringenin 8-PN4.4 ? ? ?Xenoestrogen
Quercetin –<0.001–0.010.002–0.040 ? ?Xenoestrogen
Ipriflavone –<0.01<0.01 ? ?Xenoestrogen
Miroestrol –0.39 ? ? ?Xenoestrogen
Deoxymiroestrol –2.0 ? ? ?Xenoestrogen
β-Sitosterol –<0.001–0.0875<0.001–0.016 ? ?Xenoestrogen
Resveratrol –<0.001–0.0032 ? ? ?Xenoestrogen
α-Zearalenol –48 (13–52.5) ? ? ?Xenoestrogen
β-Zearalenol –0.6 (0.032–13) ? ? ?Xenoestrogen
Zeranol α-Zearalanol48–111 ? ? ?Xenoestrogen
Taleranol β-Zearalanol16 (13–17.8)140.80.9Xenoestrogen
Zearalenone ZEN7.68 (2.04–28)9.45 (2.43–31.5) ? ?Xenoestrogen
Zearalanone ZAN0.51 ? ? ?Xenoestrogen
Bisphenol A BPA0.0315 (0.008–1.0)0.135 (0.002–4.23)19535Xenoestrogen
Endosulfan EDS<0.001–<0.01<0.01 ? ?Xenoestrogen
Kepone Chlordecone0.0069–0.2 ? ? ?Xenoestrogen
o,p'-DDT –0.0073–0.4 ? ? ?Xenoestrogen
p,p'-DDT –0.03 ? ? ?Xenoestrogen
Methoxychlor p,p'-Dimethoxy-DDT0.01 (<0.001–0.02)0.01–0.13 ? ?Xenoestrogen
HPTE Hydroxychlor; p,p'-OH-DDT1.2–1.7 ? ? ?Xenoestrogen
Testosterone T; 4-Androstenolone<0.0001–<0.01<0.002–0.040>5000>5000Androgen
Dihydrotestosterone DHT; 5α-Androstanolone0.01 (<0.001–0.05)0.0059–0.17221–>500073–1688Androgen
Nandrolone 19-Nortestosterone; 19-NT0.010.2376553Androgen
Dehydroepiandrosterone DHEA; Prasterone0.038 (<0.001–0.04)0.019–0.07245–1053163–515Androgen
5-Androstenediol A5; Androstenediol6173.60.9Androgen
4-Androstenediol –0.50.62319Androgen
4-Androstenedione A4; Androstenedione<0.01<0.01>10000>10000Androgen
3α-Androstanediol 3α-Adiol0.070.326048Androgen
3β-Androstanediol 3β-Adiol3762Androgen
Androstanedione 5α-Androstanedione<0.01<0.01>10000>10000Androgen
Etiocholanedione 5β-Androstanedione<0.01<0.01>10000>10000Androgen
Methyltestosterone 17α-Methyltestosterone<0.0001 ? ? ?Androgen
Ethinyl-3α-androstanediol 17α-Ethynyl-3α-adiol4.0<0.07 ? ?Estrogen
Ethinyl-3β-androstanediol 17α-Ethynyl-3β-adiol505.6 ? ?Estrogen
Progesterone P4; 4-Pregnenedione<0.001–0.6<0.001–0.010 ? ?Progestogen
Norethisterone NET; 17α-Ethynyl-19-NT0.085 (0.0015–<0.1)0.1 (0.01–0.3)1521084Progestogen
Norethynodrel 5(10)-Norethisterone0.5 (0.3–0.7)<0.1–0.221453Progestogen
Tibolone 7α-Methylnorethynodrel0.5 (0.45–2.0)0.2–0.076 ? ?Progestogen
Δ4-Tibolone 7α-Methylnorethisterone0.069–<0.10.027–<0.1 ? ?Progestogen
3α-Hydroxytibolone –2.5 (1.06–5.0)0.6–0.8 ? ?Progestogen
3β-Hydroxytibolone –1.6 (0.75–1.9)0.070–0.1 ? ?Progestogen
Footnotes:a = (1) Binding affinity values are of the format "median (range)" (# (#–#)), "range" (#–#), or "value" (#) depending on the values available. The full sets of values within the ranges can be found in the Wiki code. (2) Binding affinities were determined via displacement studies in a variety of in-vitro systems with labeled estradiol and human ERα and ERβ proteins (except the ERβ values from Kuiper et al. (1997), which are rat ERβ). Sources: See template page.

Ecology

Phytoestrogens are involved in the synthesis of antifungal benzofurans and phytoalexins, such as medicarpin (common in legumes), and sesquiterpenes, such as capsidiol in tobacco. [19] Soybeans naturally produce isoflavones, and are therefore a dietary source for isoflavones.

Phytoestrogens are ancient naturally occurring substances, and as dietary phytochemicals they are considered to have coevolved with mammals. In the human diet, phytoestrogens are not the only source of exogenous estrogens. Xenoestrogens (novel, man-made), are found as food additives [20] and ingredients, and also in cosmetics, plastics, and insecticides. Environmentally, they have similar effects as phytoestrogens, making it difficult to clearly separate the action of these two kind of agents in studies. [21]

Avian studies

The consumption of plants with unusual content of phytoestrogens, under drought conditions, has been shown to decrease fertility in quail. [22] Parrot food as available in nature has shown only weak estrogenic activity. Studies have been conducted on screening methods for environmental estrogens present in manufactured supplementary food, with the purpose of aiding reproduction of endangered species. [23]

Food sources

According to one study of nine common phytoestrogens in a Western diet, foods with the highest relative phytoestrogen content were nuts and oilseeds, followed by soy products, cereals and breads, legumes, meat products, and other processed foods that may contain soy, vegetables, fruits, alcoholic, and nonalcoholic beverages. Flax seed and other oilseeds contained the highest total phytoestrogen content, followed by soybeans and tofu. [24] The highest concentrations of isoflavones are found in soybeans and soybean products followed by legumes, whereas lignans are the primary source of phytoestrogens found in nuts and oilseeds (e.g. flax) and also found in cereals, legumes, fruits and vegetables. Phytoestrogen content varies in different foods, and may vary significantly within the same group of foods (e.g. soy beverages, tofu) depending on processing mechanisms and type of soybean used. Legumes (in particular soybeans), whole grain cereals, and some seeds are high in phytoestrogens.

A more comprehensive list of foods known to contain phytoestrogens includes:

Food content of phytoestrogens is very variable and accurate estimates of intake are therefore difficult and depends on the databases used. [31] Data from the European Prospective Investigation into Cancer and Nutrition found intakes between 1 mg/d in Mediterranean Countries and more than 20 mg/d in the United Kingdom. [32] The high intake in the UK is partly explained by the use of soy in the Chorleywood bread process. [33] A 2001 epidemiological study of women in the United States found that the dietary intake of phytoestrogens in healthy post-menopausal Caucasian women is less than one milligram daily. [34]

Effects on humans

In humans, phytoestrogens are digested in the small intestine, poorly absorbed into the circulatory system, circulate in plasma, and are excreted in the urine. Metabolic influence is different from that of grazing animals due to the differences between ruminant versus monogastric digestive systems. [21]

As of 2020, there is insufficient clinical evidence to determine that phytoestrogens have effects in humans. [35]

Females

It is unclear if phytoestrogens have any effect on the cause or prevention of cancer in women. [1] [36] Some epidemiological studies have suggested a protective effect against breast cancer. [1] [36] [37] Additionally, other epidemiological studies found that consumption of soy estrogens is safe for patients with breast cancer, and that it may decrease mortality and recurrence rates. [1] [38] [39] It remains unclear if phytoestrogens can minimize some of the deleterious effects of low estrogen levels (hypoestrogenism) resulting from oophorectomy, menopause, or other causes. [36] A Cochrane review of the use of phytoestrogens to relieve the vasomotor symptoms of menopause (hot flashes) stated that there was no conclusive evidence to suggest any benefit to their use, although genistein effects should be further investigated. [40]

Males

It is unclear if phytoestrogens have any effect on male sexuality, with conflicting results about the potential effects of isoflavones originating from soy. [1] Some studies showed that isoflavone supplementation had a positive effect on sperm concentration, count, or motility, and increased ejaculate volume. [41] [42] Sperm count decline and increasing rate of testicular cancers in the West may be linked to a higher presence of isoflavone phytoestrogens in the diet while in utero, but such a link has not been definitively proven. [43] Furthermore, while there is some evidence that phytoestrogens may affect male fertility, more recent reviews of available studies found no link, [44] [45] and instead suggests that healthier diets such as the Mediterranean diet might have a positive effect on male fertility. [45] Neither isoflavones nor soy have been shown to affect male reproductive hormones in healthy individuals. [44] [46]

Infant formula

Some studies have found that some concentrations of isoflavones may have effects on intestinal cells. At low doses, genistein acted as a weak estrogen and stimulated cell growth; at high doses, it inhibited proliferation and altered cell cycle dynamics. This biphasic response correlates with how genistein is thought to exert its effects. [47] Some reviews express the opinion that more research is needed to answer the question of what effect phytoestrogens may have on infants, [48] [49] but their authors did not find any adverse effects. Studies conclude there are no adverse effects in human growth, development, or reproduction as a result of the consumption of soy-based infant formula compared to conventional cow-milk formula. [50] [51] [52] The American Academy of Pediatrics states: "although isolated soy protein-based formulas may be used to provide nutrition for normal growth and development, there are few indications for their use in place of cow milk-based formula. These indications include (a) for infants with galactosemia and hereditary lactase deficiency (rare) and (b) in situations in which a vegetarian diet is preferred." [53]

Ethnopharmacology

In some countries, phytoestrogenic plants have been used for centuries in the treatment of menstrual and menopausal problems, as well as for fertility problems. [54] Plants used that have been shown to contain phytoestrogens include Pueraria mirifica [55] and its close relative kudzu, [56] Angelica, [57] fennel, [28] and anise. In a rigorous study, the use of one such source of phytoestrogen, red clover, has been shown to be safe, but ineffective in relieving menopausal symptoms [58] (black cohosh is also used for menopausal symptoms, but does not contain phytoestrogens [59] ).

See also

Related Research Articles

<span class="mw-page-title-main">Estrogen</span> Primary female sex hormone

Estrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal activity: estrone (E1), estradiol (E2), and estriol (E3). Estradiol, an estrane, is the most potent and prevalent. Another estrogen called estetrol (E4) is produced only during pregnancy.

<span class="mw-page-title-main">Soybean</span> Legume grown for its edible bean

The soybean, soy bean, or soya bean is a species of legume native to East Asia, widely grown for its edible bean, which has numerous uses.

<span class="mw-page-title-main">Polyphenol</span> Class of chemical compounds

Polyphenols are a large family of naturally occurring phenols. They are abundant in plants and structurally diverse. Polyphenols include phenolic acids, flavonoids, tannic acid, and ellagitannin, some of which have been used historically as dyes and for tanning garments.

Hot flashes are a form of flushing, often caused by the changing hormone levels that are characteristic of menopause. They are typically experienced as a feeling of intense heat with sweating and rapid heartbeat, and may typically last from two to 30 minutes for each occurrence.

<span class="mw-page-title-main">Equol</span> Isoflavandiol estrogen metabolized from daidzein

Equol (4',7-isoflavandiol) is an isoflavandiol estrogen metabolized from daidzein, a type of isoflavone found in soybeans and other plant sources, by bacterial flora in the intestines. While endogenous estrogenic hormones such as estradiol are steroids, equol is a nonsteroidal estrogen. Only about 30–50% of people have intestinal bacteria that make equol.

The lignans are a large group of low molecular weight polyphenols found in plants, particularly seeds, whole grains, and vegetables. The name derives from the Latin word for "wood". Lignans are precursors to phytoestrogens. They may play a role as antifeedants in the defense of seeds and plants against herbivores.

Isoflavones are substituted derivatives of isoflavone, a type of naturally occurring isoflavonoids, many of which act as phytoestrogens in mammals. Isoflavones occur in many plant species, but are especially high in soybeans.

<span class="mw-page-title-main">Genistein</span> Chemical compound

Genistein (C15H10O5) is a naturally occurring compound that structurally belongs to a class of compounds known as isoflavones. It is described as an angiogenesis inhibitor and a phytoestrogen.

<span class="mw-page-title-main">Daidzein</span> Chemical compound

Daidzein is a naturally occurring compound found exclusively in soybeans and other legumes and structurally belongs to a class of compounds known as isoflavones. Daidzein and other isoflavones are produced in plants through the phenylpropanoid pathway of secondary metabolism and are used as signal carriers, and defense responses to pathogenic attacks. In humans, recent research has shown the viability of using daidzein in medicine for menopausal relief, osteoporosis, blood cholesterol, and lowering the risk of some hormone-related cancers, and heart disease. Despite the known health benefits, the use of both puerarin and daidzein is limited by their poor bioavailability and low water solubility.

<span class="mw-page-title-main">Soy protein</span> A protein that is isolated from soybean

Soy protein is a protein that is isolated from soybean. It is made from soybean meal that has been dehulled and defatted. Dehulled and defatted soybeans are processed into three kinds of high protein commercial products: soy flour, concentrates, and isolates. Soy protein isolate has been used since 1959 in foods for its functional properties.

<span class="mw-page-title-main">Soybean meal</span> Ground soybeans used for food

Soybean meal is used in food and animal feeds, principally as a protein supplement, but also as a source of metabolizable energy. Typically 1 bushel of soybeans yields 48 lbs. (21.8 kg) of soybean meal. Soybean meal is produced as a co-product of soybean oil extraction. Some, but not all, soybean meal contains ground soybean hulls. Soybean meal is heat-treated during production, to denature the trypsin inhibitors of soybeans, which would otherwise interfere with protein digestion.

<span class="mw-page-title-main">Coumestrol</span> Chemical compound

Coumestrol is a natural organic compound in the class of phytochemicals known as coumestans. Coumestrol was first identified as a compound with estrogenic properties by E. M. Bickoff in ladino clover and alfalfa in 1957. It has garnered research interest because of its estrogenic activity and prevalence in some foods, including soybeans, brussels sprouts, spinach and a variety of legumes. The highest concentrations of coumestrol are found in clover, Kala Chana, and Alfalfa sprouts.

<span class="mw-page-title-main">Biochanin A</span> Chemical compound

Biochanin A is an O-methylated isoflavone. It is a natural organic compound in the class of phytochemicals known as flavonoids. Biochanin A can be found in red clover in soy, in alfalfa sprouts, in peanuts, in chickpea and in other legumes.

<span class="mw-page-title-main">Formononetin</span> Chemical compound

Formononetin is an O-methylated isoflavone.

<span class="mw-page-title-main">Genistin</span> Chemical compound

Genistin is an isoflavone found in a number of dietary plants like soy and kudzu. It was first isolated in 1931 from the 90% methanol extract of a soybean meal, when it was found that hydrolysis with hydrochloric acid produced 1 mole each of genistein and glucose. Chemically it is the 7-O-beta-D-glucoside form of genistein and is the predominant form of the isoflavone naturally occurring in plants. In fact, studies in the 1970s revealed that 99% of the isoflavonoid compounds in soy are present as their glucosides. The glucosides are converted by digestive enzymes in the digestive system to exert their biological effects. Genistin is also converted to a more familiar genistein, thus, the biological activities including antiatherosclerotic, estrogenic and anticancer effects are analogous.

Xenohormones or environmental hormones are compounds produced outside of the human body which exhibit endocrine hormone-like properties. They may be either of natural origin, such as phytoestrogens, which are derived from plants, or of synthetic origin. These compounds can cause endocrine disruption by multiple mechanisms including acting directly on hormone receptors, affecting the levels of natural hormones in the body, and by altering the expression of hormone receptors. The most commonly occurring xenohormones are xenoestrogens, which mimic the effects of estrogen. Other xenohormones include xenoandrogens and xenoprogesterones. Xenohormones are used for a variety of purposes including contraceptive & hormonal therapies, and agriculture. However, exposure to certain xenohormones early in childhood development can lead to a host of developmental issues including infertility, thyroid complications, and early onset of puberty. Exposure to others later in life has been linked to increased risks of testicular, prostate, ovarian, and uterine cancers.

<span class="mw-page-title-main">8-Prenylnaringenin</span> Chemical compound

8-Prenylnaringenin (8-PN; also known as flavaprenin, (S)-8-dimethylallylnaringenin, hopein, or sophoraflavanone B) is a prenylflavonoid phytoestrogen. It is reported to be the most estrogenic phytoestrogen known. The compound is equipotent at the two forms of estrogen receptors, ERα and ERβ, and it acts as a full agonist of ERα. Its effects are similar to those of estradiol, but it is considerably less potent in comparison.

Postmenopausal confusion, also commonly referred to as postmenopausal brain fog, is a group of symptoms of menopause in which women report problems with cognition at a higher frequency during postmenopause than before.

<span class="mw-page-title-main">Rimostil</span> Dietary supplement

Rimostil is a dietary supplement and extract of isoflavones from red clover which was under development by Kazia Therapeutics for the prevention of postmenopausal osteoporosis and cardiovascular disease and for the treatment of menopausal symptoms and hyperlipidemia but was never approved for medical use. It is enriched with isoflavone phytoestrogens such as formononetin, biochanin A, daidzein, and genistein, and is proposed to act as a selective estrogen receptor modulator, with both estrogenic and antiestrogenic effects in different tissues. The extract reached phase II clinical trials for cardiovascular disorders, hyperlipidemia, and postmenopausal osteoporosis prior to the discontinuation of its development in 2007.

<i>Soy boy</i> Pejorative term for men perceived as non-masculine

Soy boy is a pejorative term sometimes used in online communities to describe men perceived to be lacking masculine characteristics. The term bears many similarities and has been compared to the slang terms cuck, nu-male and low-T – terms sometimes used as insults for male femininity by online communities.

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