You often hear soy products like tofu, tempeh, and soy milk are bad for women’s hormones and overall health. Let’s see whether this is true.
Soy products contain high amounts of isoflavones, which are estrogen-like compounds.
Could they disrupt natural estrogen levels in women, as anabolic steroids disrupt natural testosterone in men?
In a year long study 17 of 34 women consumed an isoflavone amount equal to about 250 g (10 oz) tofu per day [Maskarinec 2001].
Their natural estrogen did not decrease at all compared to the ones eating a ‘normal’ diet (see image).
In fact, because they are estrogen-like, isoflavones may also have estrogen-like effects, such as muscle growth. A recent study in rats supports this hypothesis [Zheng 2017].
So there you go: consuming more soy as a woman may in fact be anabolic.
However, don’t take this to the extreme by shoving a soy milk hose up your face: too much soy could potentially cause issues in women trying to get pregnant [Pautisal 2010].
Moderation is key. A tofu meal here and there will probably be good for your physique if you consume enough overall protein building blocks (additional protein from grains, seeds, and optionally animal sources).