High Quality Content by WIKIPEDIA articles! Daidzein structurally belongs to the group of isoflavones. Daidzein and other isoflavone compounds, such as genistein, are present in a number of plants and herbs like the Thai Kwao Krua or Pueraria mirifica, Kudzu or Pueraria lobata, and in food sources such as soybeans and soy products like tofu and textured vegetable protein. Soy isoflavones are a group of compounds found in and isolated from the soybean. Of note, total isoflavones in soy beans are—in general—37 percent daidzein, 57 percent genistein and 6 percent glycitein, according to USDA data. Soy germ contains 41.7 percent daidzein. Besides functioning as antioxidants, isoflavones have been shown to interact with animal and human estrogen receptors, and are therefore referred to as phytoestrogens. Soy isoflavones also produce non-hormonal effects.