Isoflavones

Isoflavones are considered to be secondary plant compounds and thus, unlike fats, proteins (protein) and carbohydrates, substances with no nutritional value – “anutritive ingredients”.

The most common isoflavones include:

  • Biochanin A
  • Coumestrol
  • Daidzein
  • Formononentin
  • Genistein
  • Glycitein
  • Orobol
  • Prateness
  • Prenylnaringenin
  • Prunetin
  • Santal

Isoflavones are found particularly in soybeans and products derived from them, as well as in numerous vegetables and fruits, such as apples, onions, and tea leaves. The highest concentrations of flavonoids are found directly in or under the hull of fruits and vegetables – correspondingly, the isoflavone concentration of soybean is 5 to 6 times higher in the seed coat than in the cotyledon. In the soybean, the isoflavones are not present freely as aglycones but mainly bound to sugars as glycosides. The three best-known isoflavones include genistein, daidzein and glycitein. Soybeans contain these compounds in a ratio of 10: 8: 1. Finally, genistein is the most relevant component of soybeans in terms of quantity – over 50% – followed by daidzein – over 40% – and glycitein – over 5-10%. In fermented soy products, such as tempeh or miso – a Japanese paste made from soybeans with variable amounts of rice, barley or other grains – aglycones predominate, as the sugar residue is enzymatically cleaved by the microorganisms used for fermentation.