HERBAL MEDICINES, PHYTOESTROGENS AND TOXICITY - RISK - BENEFIT CONSIDERATIONS

There are several suggested health benefits of phytoestrogens, particu larly those found in soy products, Herbal medicines are also widely th ought to confer health benefits, Additionally, drugs are prescribed to improve human health, but unlike phytoestrogens and herbal medicines, toxicities are defined in experimental animals and monitored in human s before and after marketing, Knowledge of toxicity is crucial to decr ease the risk:benefit ratio; this knowledge defines appropriate condit ions for use and strategies for development of safer products. However , our awareness of the toxicity of herbal medicines and phytoestrogen- containing foods is dramatically limited compared to drugs, Some aspec ts of the toxicity of herbal medicines are briefly reviewed; it is con cluded that virtually all of our knowledge is derived from human expos ures leading to acute toxicities, Importantly, detection of toxicity i s sporadic, and little information is available from prior animal expe rimentation, Additionally, well-organized monitoring of human populati ons (as occurs for drugs) is virtually nonexistent. Important toxiciti es with long latencies are particularly difficult to associate with a causative agent during or even after large scale exposures, as exempli fied by tobacco smoking and lung cancer; estrogen replacement therapy and endometrial cancer; diethylstilbestrol and reproductive tract canc ers; and fetal alcohol exposure and birth defects, These consideration s suggest that much closer study in experimental animals and human pop ulations exposed to phytoestrogen-containing products, and particularl y soy-based foods, is necessary, Among human exposures, infant soy for mula exposure appears to provide the highest of all phytoestrogen dose s, and this occurs during development, often the most sensitive life-s tage for induction of toxicity, Large, carefully controlled studies in this exposed infant population are a high priority.