Soy is a popular food these days, and is widely used in supplementation and nutrition replacement. You can now buy soy milk, soy burgers, soy flour, soy cereals, soy candy, soy protein, and plain ol’ tofu. Many health claims are being bandied about for this little bean, not the least of which is that it has estrogenic properties.
Soy does indeed have estrogenic properties. It contains phytoestrogens, which are produced by plants and mimic the action of estrogens at the body’s estrogen receptors. Because they are weaker than the estrogens that your own body produces, yet compatible with the estrogen receptors, they compete with estrogens at the estrogen receptor sites, and when bound to the estrogen receptor they block the effects of the stronger estrogens.
It has been speculated that a diet high in soy can have hormonally feminizing effects. This has almost no basis in fact, and really, makes very little sense. The beneficial effects of dietary soy are more related to the fact that it inhibits the action of estrogen, not that it has estrogenic effects itself. These inhibitory effects seem to decrease the risk of coronary heart disease (CHD) as well as breast and uterine cancer, but only when taken as part of a complete program.
What does this mean for trans women? Well, at the feminizing doses of estrogen that most trans women take, I don’t think that a diet rich in soy would noticeably inhibit fat redistribution, breast growth, or any of the other desirable effects.
If a trans woman chooses to have surgery, soy might be one component of a diet that reduces the risk of CHD and cancer, just like it is in non-trans women. However, soy is not a magic pill— it is just another substance that can be good or bad for you, depending on what your situation is.