"Effects of chronic administration of Stevia rebaudiana on fertility in rats."
https://www.ncbi.nlm.nih.gov/pubmed/10619379
Abstract
A study conducted on prepubertal male rats showed that chronic administration (60 days) of a Stevia rebaudiana aqueous extract produced a decrease in final weight of testis, seminal vesicle and cauda epididymidis. In addition, the fructose content of the accessory sex glands and the epididymal sperm concentration are decreased. Stevia treatment tended to decrease the plasma testosterone level, probably by a putative affinity of glycosides of extract for a certain androgen receptor, and no alteration occurred in luteinizing hormone level. These data are consistent with the possibility that Stevia extracts may decrease the fertility of male rats
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