I am not a fan of soy, and I think it poses more problems than it offers in benefits. This article takes a clear look at some of the evidence.
The topic of soy can create a big debate among healthy folks, and the viewpoints can be extreme. Who knew a humble green bean could be so controversial? Some tout soy products as a panacea for health and wellness, while others swear that soy is a sure ticket to infertility and "man boobs". What are the facts?
Asians don't actually eat as much soy as we think -- only about 10-36 grams per day. In contrast, a cup of tofu or soy milk contains over 200 grams of soy. Besides, the most common soy foods in Asia are fermented products such as tempeh, miso and shoyu (soy sauce), while most Westerners eat unfermented, highly processed versions of soy. Unfermented soy contains enzyme inhibitors that block protein digestion (among other things we'll get to below).
Most soy foods are highly processed and bear very little resemblance to the natural soybean (think soy hotdogs or TVP -- textured vegetable protein). Just because something is touted as a "health" food, doesn't really make it healthy. Whole foods are always the best way to get your food nutrition -- the more processed a food is, the less natural and ultimately less healthy it is.
Soy is more filler than food. For many years, the protein left over from the extraction of soy oil was sold to farms as animal feed. After some time, the food industry figured out how to make this highly processed soy protein palatable to the human tongue and began to aggressively market it in foods like soy dogs, soy meat substitutes and the like. Sure, there's protein, but it also takes quite a bit of sugar, salt or MSG to make soy protein actually taste good. The healthiest foods are whole foods, not processed ones.
Unfermented soy can inhibit protein absorption, cause flatulence and increase the chance of developing kidney stones. The processing of soy may remove some of these problems. Soy also inhibits growth. Even within the animal feed industry, the amount of soy protein that can be fed to animals has to be limited or the animals themselves will suffer problems with growth and fertility.
Most soy grown in the world is genetically modified (GM) -- with 87% of American soy being GM. And what's the big deal about that? Not a lot of research has been done on the effects of GM foods, but one particular study on rats showed that unborn babies and young infants were particularly harmed by the effects of genetically modified soy.
Soy infant formula, a common alternative to cow's milk for lactose-intolerant babies, contains endocrine disruptors and phytoestrogens, plant hormones which have been shown to cause premature puberty in young girls and delayed puberty in adolescent boys. It's a bit like giving a baby birth control pills. Soy infant formula also contributes to soy allergies. (Breast milk is undoubtedly the best food for babies, and if that's not an option, goat's milk is the next best thing to try.)
Soy is among the 8 most common food allergens, with reactions being particularly common among children.
That remains uncertain. However, unless you buy strictly organic, you can bet your soy products are heavily contaminated with pesticides. As a matter of fact, soy is the most contaminated crop we grow in the United States. And don't forget, non-organic soy is almost certainly genetically modified as well.
The huge global demand for soy (for use in processed foods, animal feed and biofuels) is eating up the rainforest, because farmers have been financially motivated to clear more rainforest land in order to plant this export crop. More deforestation, more global warming.
Actually, for many, soy farming is less like employment and more like slavery. Although slavery was officially outlawed in Brazil over 130 years ago, debt bondage for over 25,000 people continues on Brazilian soy plantations. This is not the kind of farming industry I want to support.
Bottom line: soy is not the magical health food that many tout it to be. Let's be clear, however, that fermented soy products don't carry the same negative consequences as unfermented, highly processed soy foods. So if you're shopping for miso or tempeh, make sure to choose brands that are organic and not genetically modified. And if you've been depending on tofu (an unfermented food) for vegetarian protein, try out some of these other vegetarian proteins instead.