Soy is Detrimental to the Development of Young Men

Let us, for a moment, put aside all claims that amount to nothing more than correlation as opposed to causation, including the apparent "infertility" of Asian men (the place with the greatest number of people in the world has apparently been having trouble having kids for thousands of years), and generally reduced testosterone levels that even my opponent agrees (to a more limited extent than is actually true) are inherently affected by millions of confounding variables. What we're left with is one claim: that soy turns boys into girly boys. And it's wrong. PhytoestrogenIf you ate 100g of raw uncooked soybeans, that's 200mg of isoflavone, which is the key form of phytoestrogen we're talking about here (2). That's a lot. HOWEVER, nobody eats raw uncooked soybeans. Processing and fermentation reduces this MUCH further - soy milk has 9.65mg per 100g (8), while soy sauce contains none at all (1). As the experts say, "It would be difficult to consume too much isoflavone from natural soy products" (2). The fact is that many soy products contain none of the stuff, and despite having a lot more than other foods, those that do still only have very little. Of course the exact amounts will vary for different products - Iowa State University did a huge study in 1999 which gives some very interesting means (8). Moreover, not everybody can actually metabolize all isoflavones. The best study we have on this was a large sample of western people, and it found that only about a third of people can metabloize a given isoflavone, so the vast majority of them are simply excreted (6). Moreover, not all of those isoflavones will act like estrogen. Isoflavones are not estrogen, but what scientists call "selective estrogen receptor modulators" (SERMs), which can both inhibit and stimulate estrogen activity depending on what kind of tissue they bond to (3). It's worth remembering that estrogen is in fact a required compound in a healthy body, to the point where the fitness experts will often recommend SERMs in place of estrogen because of their weaker estrogenic effect because they can cancel themselves out as well (4), and the simple fact that the estrogen produced naturally in a male body has an effect around 1000 times stronger (5). Scientists are currently trying to figure out whether they can produce a soy SERM isoflavone that inhibits estrogen in the reproductive system and stimulates it everywhere else. That would help prevent pretty much every type of cancer men can get. Sadly, it's not quite reality yet. Point is, eating 100g of Tofu at dinner is like crushing an estrogen pill, taking a very small granule, and then playing a game of roulette to determine whether you have to add that tiny granule to your dinner. To be honest, even if you eat that tiny granule outright without your dinner, it's not very likely anything horrible will happen to you or your future sexual health. Now of course, if you repeat that every single day for long enough, then there might be some very small side effects (not that there's anything WRONG with that - I have a good friend who's transgendered and takes huge amounts of estrogen pills each day, but that does NOT mean there's anything wrong with them). This is, however, the same with any food. Eating McDonalds every evening will likely get you slightly fatter, eating oranges will likely cause your teeth to disintegrate a little more, and so on. Like all foods, if you eat soy, soy should be eaten in moderation. What about the science? According to a very good quality-controlled and peer-reviewed study from Scotland, an additional 40mg of isoflavones has no effect on semen quality, testicular size, or anything else of relevance here in any of the people in their sample (7). Yes, that's right, this study used real people. 40mg is around 2-3 bowls of cereal with soymilk compared with regular milk, so this is a really large intake. And it's not harmful. As much as that study was about as definitive as you can get, a later 2008 study re-examined every single human study that had ever been published in a peer-reviewed journal on the effects of soybeans on testosterone concentrations. They found that in every single one of those studies (all 15, plus 36 groups that were examined for similar stuff) - EVERY ONE - no single human was found to have reduced testosterone concentrations (9). And then an even later peer-reviewed study, from 2010, proves that "isoflavones do not exert feminizing effects on men at intake levels equal to and even considerably higher than are typical for Asian males. " The study even specifically debunks one of the papers my opponent cited and carefully explains why they're not scientific (10). The difference between my opponent and myself is not our ability to find science. Believe me, I, like him, have another dozen or so studies right in front of me for why I'm right. The difference is that my research is actually relevant to the topic. Every single relevant study is on my side in this debate. While he can prove soybeans are harmful to mice and pigs, I can prove soybeans are not harmful to actual people. And since it's actual people whom this debate is about, my opponent has not demonstrated any valid science at all. After all, we're not pigs or rats. CorrelationsAside from the aforementioned obvious issue with Asian fertility, Asian men consume far fewer soybeans than Americans (11), and yet they have exactly the same average fertility rate as North America (12). What's more, asia has experienced exactly the same decline in fertility rate as the rest of the world over approximately the same period of time (13), ruling out my opponent's "evil baby-killing food from the east" theory. A much more likely suggestion that is actually based on peer-reviewed research is that women are choosing to have children at different times (the so called "tempo effect") when it is harder to measure (14), or for example that more urban communities have fewer children (16), or improvements in contraception. It has nothing to do with soy, and while diet might play some small role, it is HIGHLY unlikely to be the most significant factor. Moreover, outside of the one state my opponent wanted to talk about, all the rest of the USA actually has a very stable birth rate, and this is projected to continue (15). ConclusionAll the actual science is on my side, it makes sense from a theoretical point of view, and there's no real-world data to refute it. The resolution is negated. Sources1 - . http://www.soyfoods.com...2 - . http://extension.agron.iastate.edu...3 - . http://en.wikipedia.org...4 - . http://voices.yahoo.com...5 - . http://thechart.blogs.cnn.com...6 - . http://www.ncbi.nlm.nih.gov...7 - . http://www.ncbi.nlm.nih.gov...8 - . http://www.nal.usda.gov...9 - . http://www.fertstert.org...10- . http://www.fertstert.org...11- . http://www.spectrumcommodities.com...12- . http://en.wikipedia.org...13- . http://blendedpurple.blogspot.co.nz...14- . http://onlinelibrary.wiley.com...15- . http://www.ifs.du.edu...16- . http://www.ncbi.nlm.nih.gov...