Soy Protein Supplementation Is Not Adipogenic Or Estrogenic In Young Men When Combined With Resistance Training

Abstract

PURPOSE: Sex hormone physiology (e.g., estradiol, testosterone) may be affected by soy and/or whey protein consumption. Alterations in sex hormones due to resistance training (RT) and/or protein supplementation may explain meaningful variation in adipocyte and skeletal myocyte size alterations. Consequential molecular signaling in these cell types remain unclear. Therefore, we examined effects of RT and soy (SPC), whey (WPC), or placebo (PLA) supplementation in young men. METHODS: 47 healthy, young men were partitioned into PLA, SPC, or WPC groups and completed 12 weeks of RT. Body composition, serum hormones, androgen signaling markers in myocytes, and estrogen signaling markers in adipocytes were examined using DXA, ELISA, western blotting, PCR, and immunohistochemistry. RESULTS: Testosterone increased over time, but more so in subjects consuming WPC (p<0.05). Adipocyte mRNA expression of the estrogen receptor alpha increased (p<0.05), as did hormone sensitive lipase over time (p<0.05). Skeletal muscle androgen receptor mRNA expression increased while ornithine decarboxylase mRNA decreased over time (p<0.05). Alterations in body composition, adipocyte, and myocyte morphology were not significantly different between groups (p>0.05). Changes in 17β-estradiol and testosterone explained <3% of alterations in adipocyte and myocyte size. CONCLUSIONS: These data suggest primarily RT-mediated effects with little influence of protein type and hormonal changes.