Reed et al. 2021 — Neither soy nor isoflavone intake affects male reproductive hormones: a meta-analysis

What the study found

This expanded and updated meta-analysis pooled dozens of clinical studies to test whether eating soy or taking isoflavone supplements changes men's reproductive hormones. The authors concluded that neither soy nor isoflavone intake affected those hormones, including testosterone. ^[1]

neither soy nor isoflavone intake affects male reproductive hormones

^[1]

Why it matters here

A recurring manosphere talking point holds that soy consumption lowers men's testosterone and undermines masculinity. This meta-analysis, drawing on many clinical trials, directly contradicts that claim by finding no measurable effect on male reproductive hormones. It is relevant to the broader question of whether testosterone is collapsing, because it removes one of the most commonly cited dietary explanations for a supposed decline.