Phytoestrogens

Phytoestrogens, also known as phytoestrogens, are secondary plant substances belonging to the polyphenols, which are mainly found in cereals, vegetables, legumes and fruit. They are similar in structure and effect to the female sex hormones, but are much less effective.

Chemically, phytoestrogens belong to the three structural classes:

• Cumestans are also called coumaronocoumarins (coumesterol, 4'-methoxycumestrol). They are mainly found in vegetable sprouts such as lucerne or bean sprouts).
• Isoflavones (genistein, daidzein in red clover and soya)
• lignans (linseeds, sesame seeds, sunflower seeds).

Phytoestrogens are similar to human 17beta-estradiol and, like this, bind to the human beta-estrogen receptors (see belowoestrogen receptors). In this respect they are also called selective estrogen receptor modulators(SERMsor phyto-SERMs). Phytoestrogens do not influence the FSH-, LH- or prolactin levels (Schilcher H 2016). In the uterine lining and in the mammary gland mainly alpha-oestrogen receptors are expressed, with which the phyto-SERMS usually do not form bonds. Phytoestrogens are therefore comparable to the effect of hormone replacement therapy.

Further sources of phytoestrogens are legumes, cereal bran and cereals. In somewhat lower concentrations they are also found in many vegetables and fruits, seeds, hops, sage, tea and some alcoholic drinks such as beer, wine and bourbon (whiskey).

The actual biological significance of these polyphenolic compounds is their properties as dyes. Furthermore, they act as tanning and bittering agents and thus as repellents against predators. Many phytoestrogens also have a microbicidal effect.

Soybeans in particular are rich in isoflavones and are offered as a biological alternative for hormone replacement therapies for women in the menopause. This "dietary food for special medical purposes" is said to help against osteoporosis, other menopausal complaints.

The term "phytoestrogen" was coined by the Finnish scientist Herman Adlercreutz in the broad half of the 20th century.

1. Ammon H et al (2014). Hunnius Pharmaceutical Dictionary. Walter de Gruyter GmbH Berlin/Boston S 1402

2. Heger M et al.(2006) Menopause. J North American Menopause Society. 13: 744-759
3. Schilcher H Gynecological diseases and obstetrics. In: Guide to Phytotherapy. Urban and Fischer Publishing House Munich, S. 767