Effect of soy protein isolate supplementation on the estradiol biosynthesis pathway in a female rat model

BackgroundSoy protein isolate (SPI) has gained popularity as an alternative to animal proteins.Soy consumption may have a link to rising serum estrogen in humans. This concernis attributed to phytoestrogens, specifically isoflavones present in soy protein,acting as estrogen substitutes and modulators.ObjectiveThe objective of this research was to assess the influence of SPI supplementationon estradiol hormone levels and the expression of genes associated with estrogensynthesis in female rats.Materials and methodsFemale Wistar rats (n=18) were evenly divided into three groups: group 1 (normalcontrol) received oral administration of a saline vehicle. Group 2 (low dose)received 450 mg/kg body weight of SPI for 30 days. Group 3 (high dose)received 900 mg/kg body weight of SPI for 30 days. All administrations wereconducted intragastrically.Results and conclusionThe results of our study indicate that there was a significant increase in the levels ofestradiol hormone in groups receiving low and high doses of SPI when comparedwith the control group. There was an upregulation in the messenger ribonucleic acidexpression of the Cyp19 gene in low-dose and high-dose groups. Moreover, thelow-dose group showed upregulation in the expression of the HSD3B gene. Thesegenes are involved in the biosynthesis pathway of estrogen hormone in females.Therefore, the use of SPI should be cautious because it contains phytoestrogens(isoflavones), which have structural similarities to endogenous female estrogen andmay cause hormonal disturbance in females.