Natural Compounds and their Biological Activity. 4. Natural phytoestrogens, occurrence in feed chain, positive and negative effects

The study analyses the biological activity of natural endogenous estrogens and its effects in the process of human and animal ontogenesis as the basis for comparison with effects of phytoestrogens. From the whole range of these substances is this study focused on isoflavones, coumarines and lignans only. These substances are present in important fodder crops and can be part of foodstuffs or row material used for production of food supplements. The study analyses its positive and negative physiological effects in animal nutrition. The study concludes that the phytoestrogens are not necessary in animal nutrition, rather harmful and can cause negative effects. It can be present also in foodstuffs of animal origin (milk, eggs) and be consumed, which is undesirable especially by children. On the other hand, the phytoestrogens have positive effects on human health in the pre-menopausal period and during climacterium (women) and during the male climacterium.CZ; cs; klara.bauerova@mze.c