Soy Intake Since the Prepubertal Age May Contribute to the Pathogenesis of Endometriosis in Adulthood

High prevalence of endometriosis was reported in Asian women as a result of their traditionally high intake of soy foods during infancy. Soy is widely used in infant feeding after weaning from breast milk or cow milk. This study thus aimed to determine to what extent soy intake before puberty may contribute to the development of endometriosis. For this purpose, immature (6-week old) female rats were fed with various soy formulas (0%, 10%, 20%, 30%, 40%, 50%, and 60%). Normal control animals were fed with a soy-free diet. At 13 weeks of age, animals (except the normal control) underwent a transplantation surgery to establish endometriosis. Estradiol valerate and oxytocin were used to induce pelvic pain. Endometrial implant levels of glutathione (GSH) and malondialdehyde (MDA) allowed estimating tissue oxidative status. Physiological ovarian function was assessed by histological analysis of ovaries. Results showed that soy-fed animals grew faster than animals receiving a soy-free diet (P < .001). In animals supplemented with more than 10% of soy, the intensity of pelvic pain increased (P < .001) as well as the volume of ectopic foci. In addition, tissue levels of MDA and GSH increased (P < .001). The ovarian function was altered and the number of luteinized unruptured follicles increased. In conclusion, although animals supplemented with soy at the prepubertal stage displayed a good growth performance, regular soy consumption may promote the development and progress of endometriosis in adulthood, especially when soy content in food is more than 10%.