The myth of ‘moobs’ (man boobs)
“Moobs” is another of the heavily circulated soy myths with no actual basis in scientific fact. I am reminded of the fear I had of swallowing bubblegum as a child — “because it will take 7 years to digest!” Gynecomastia is the medical term for developed breasts in men. Fetal sexual organ formation and secondary sexual characteristic development are essentially hormone driven. The ‘soy causes man boobs’ urban legend is thus likely rooted in the confusion between estrogen and phytoestrogen, but, as previously explained, phytoestrogen is not estrogen. If indeed this were the case, there would be a lot of men in need of bras.
In reality, clinical studies in men show that isoflavones do not affect testosterone levels or circulating estrogen levels. Even at levels of isoflavone exposure significantly higher than those of a typical Asian male consuming a soy rich diet, isoflavones have not been found to have feminizing effects. (6)