A year or so ago, my boyfriend told me how he avoids eating too much soy because it contains some sort of pseudo-estrogen that can be harmful to men. More off-putting, he said that raw soybeans can prevent your intestines from absorbing nutrients in food, and that in extreme cases, people have even died from it. I always wondered just how much of that was true — and what better excuse to figure it out than as research for a vegetarian blog?
Reading up on soybeans, it seems like everyone thinks they’re either poison or nature’s miracle food. As is usually the case, it seems that the truth lies somewhere in between. First, the good: soybeans do have plenty of health benefits. They’re a source of omega-3 fatty acids, which have been oh so trendy to talk about in diets lately — they’re good for preventing heart disease and lowering blood pressure. (There is also evidence that it helps with rheumatoid arthritis and even cancer.) They also contain “protein, isoflavones, and fiber, all thought to provide health benefits.” More than that, the protein in soybeans is much more complete than most other plant sources, and includes all essential amino acids.” (Source)
So what’s all this about them killing you? Let’s get to the bottom of a few major claims:
“Raw soybeans contain enzyme inhibitors that prevent you from absorbing protein, so if you eat them in large amounts you can slowly starve to death.”
It’s true that uncooked soybeans contain an anti-enzyme that inhibits the ability of the small intestine to digest protein by counteracting trypsin. If you use soy as a main protein source, this isn’t what you want to hear. (Source) But you’d have to eat an awful lot of soy to starve yourself to death, and cooking destroys the trypsin blocker. Besides, who really eats raw soybeans? They taste awful and are hard to digest, just like a lot of uncooked legumes — which, surprise surprise, also contain toxins. Probably our bodies’ way of telling us, “Bad human. Cook first.”
“Even cooked, soybeans contain harmful phytates.”
There is definitely truth in this one. Raw soybeans contain phytic acid, “which binds and prevents mineral absorption (especially zinc, calcium, and magnesium),” putting people who depend heavily on soy at risk for mineral deficiencies. (Source) Cooking the beans gets rid of a lot of the phytates, but not all, which is why cultures with soy-heavy cuisine so often use fermentation. Most of the Japanese soy staples are fermented forms: tofu, soy sauce, nattō, miso. But you’ll notice that Japan is also known for edamame (which is just boiled and salted, not fermented) and they don’t seem to be dropping dead — in fact, they have the second-highest rate of centenarians in the world. It seems the key, again, is moderation. As long as you’re not living off of nothing but edamame, you should be fine.
“Soy contains ‘fake estrogen,’ so men should limit how much they eat.”
Soybeans contain a couple of compounds that mimic estrogen, which can have an impact on male fertility if eaten in large amounts. There’s still debate as to how big of an impact this is — some say it’s huge, whereas some sources claim that not only are the negative effects negligible, but that soybeans can reduce the chance of prostate cancer. (Source)
So … the verdict? As long as you don’t make a habit of munching on raw soybeans, and as long as you don’t depend entirely on soy for your protein, you’re probably fine.
Have something to add? Leave it in the comments below!
