I recently took the decision to be vegetarian (and eventually vegan, more on that later) and I like to make informed decisions and know what I’m doing when I do something. One of the more controversial topics in the “Health” and “Vegan/Vegetarian” sphere is soy; some call it a super-food, others blame it for decreasing fertility and even blame soy for "making kids gay". There isn’t a lot of agreement out there, is there? Personally, I’m not interested in opinions or anecdotes when it comes to my health or anything else that can have a significant impact on the quality of my life. Thankfully there are scientists that study these things and find out what soy really does to us.
The source of all of this disagreement is a compound found in soy called phytoestrogen, it is an estrogen-like substance produced by some plants (hence the phyto- which means plant). The consumption of plants that produce this compound has been shown to reduce fertility in some animal species, people tend to argue that if it has those effects in animals it will in humans too, but I wouldn’t put any money on those ideas, a “gut feeling” doesn’t necessarily imply truth, especially in the face of hard scientific facts:
From what I could gather most people think that consuming soy is equivalent to undergoing
sex-change hormone therapy, (okay, I might be exaggerating about some cases) its really
easy to find arguments online arguing this point (as well as a number of stories
reporting this kind of effect on themselves, others, and even citing
research). A lot of these are fairly influential sources, while not scientific, that
people tend to believe in which could be why this idea of
soy => hormone replacement
is so prominent.
According to recent research (circa 2010, see below) consuming as much phytoestrogen as a person in the Far East, where soy is a common staple, (one study states that “mean daily soy protein and isoflavone intake among Japanese adults ranges from approximately 6 to 11g and 25 to 50 mg, respectively”) has no effect on sperm counts, motility, or morphology. According to another study that focused on the effects of phytoestrogen on male hormones concluded that “[t]here was no significant pooled effect of isoflavone consumption on the hormonal profile, T [Testosterone] and SHBG(Sex hormone-binding globulin).” Can’t argue with science now can you?
Certainly these men who have reported feminizing effects of soy on themselves could be telling the truth, if the reports are true things happened to them and soy could have been the culprit. Clearly, the effects of soy, isoflavones, and phytoestrogen aren’t well understood, yet, and these men could suffer from some kind of sensitivity to these compounds, I don’t know, but these studies seem fairly conclusive, they are peer reviewed. Before you decide to kick soy remember, get yourself informed: read the scientific papers liked to below and do a thorough investigation. My conclusion is that there’s nothing to worry about.