Natural Estrogenic Substances, Origins, and Effects

Abstract

Some natural substances have been scientifically identified as estrogenic since the late 1930s when they were found to be deleterious at high doses for cattle reproduction. Several compounds belonging to different chemical families are considered here: isoflavonoids, coumestans, lignans, and resorcylic acid lactones. This list is not exhaustive. The vegetable sources of these compounds are probably not all identified yet, but all the compounds presented here were shown to act as endocrine disruptors, i.e., modifying the hormonal natural balance, at dietary doses either in human, in cattle, or in other vertebrates. Estrogenic compounds mimic estradiol activities and can interact nearly with all biological functions in lower and higher vertebrates. Some mollusks are also sensitive to estrogens. The effective dose is crucial to consider since as other endocrine disruptors the natural substances may have opposite effects at low, dietary, and pharmacological concentrations. Different cell pathways are triggered by the natural estrogenic substances, including some that are not influenced by estradiol itself, and this explains why their effect is not a monotonic dose–response line. This questions the classical toxicological approach which considers acute exposure (short and high concentrations) as the key of the toxicity evaluation. The history of human exposure to isoflavones was recently casted on doubt, reinforcing the need for careful study of these compounds’ occurrence and effects on humans. It is clear now that the traditional soy food makings were able to remove isoflavones from foodstuffs. This is no longer the case in modern processing, and this means that the exposure to this estrogenic substances has increased markedly in recent times. Estrogens in mammals can have both beneficial and harmful effects which are evoked here.