It's not uncommon for people to find out that one of there favorite "healthy foods" is actually not so healthy after all. One of those is soy. Soy is a legume that is often used as a plant protein and as an ingredient in meat alternatives. Before getting worked up, not all soy is bad! There are two types, and one is better than the other.
There are two ways people eat soy: fermented and unfermented. Millions and millions of Chinese people have been eating fermented soy for thousands of years without having any negative health effects. The problem is that in the United States unfermented soy is making its way into almost everything, which might not necessarily good. And on top of that, it's being promoted as a healthy source of protein!
There is a long-standing debate about these two and whether they're considered a health food or not. We're here to provide you with all the details and facts so you can make that decision yourself!
The Good - Fermented Soy
Soy protein is considered a complete protein because it contains all nine essential amino acids that the body needs to obtain through food sources. So why are people claiming that it's unhealthy? Well like we mentioned earlier, soy is classified into two types: fermented and unfermented. Fermented soy is the type that is commonly consumed in Asian countries Japan and China, and it's the only type that provides health benefits.
What is fermented soy?
It's a type of soy that goes through a long fermentation process. Fermented soy is cultured with beneficial bacteria, yeast, or mold. Fermenting soy improves the digestion and absorption of it in the body.
Some common sources of fermented soy are:
- Tempeh - A fermented soybean cake
- Miso - A fermented soybean paste, commonly used in miso soup
- Natto - Fermented soybeans
- Soy sauce - Traditionally fermented from soybeans, wheat, water, and salt
The good bacteria and/or probiotics found in fermented soy products help nourish gut health, boost digestion, and improves the absorptions of nutrients. Another benefit they provide is the high content of vitamin K2. Vitamin K2 is an important nutrient that supports cardiovascular and bone health. What makes fermented soy even better is that it contains the perfect form of Vitamin K - Menaquinone, MK for short. This type of vitamin provides several benefits and it stays in your body longer. It's difficult to get this vitamin from other food sources, so your best bet is to get it from fermented foods like the ones listed above.
The Bad - Unfermented Soy
Unfermented soy is the type that is commonly consumed in America, but not common in Japan and China.
What is unfermented soy?
Soy that has not gone through the fermentation process is considered unfermented. Soybeans contain anti-nutrients - saponins, soya toxin, phytates, trypsin inhibitors, goitrogens and phytoestrogens. Fermenting soy destroys these anti-nutrients so the body receives all the nutritional benefits. So the unfermented soy contains all these anti-nutrients that can have adverse effects in the body.
Common unfermented soy products:
- Soy milk
- Vegan meat substitutes
- Soy protein isolate (in protein bars and shakes)
- Soy cheese
- Vegetable oils
Why is unfermented soy bad?
Unfermented soy is an anti-nutrient. This means that it will keep your body from absorbing minerals like calcium, magnesium, and especially zinc (all minerals that your body needs to function properly). This can lead to a mineral deficiency, especially for those who don't eat meat. But just wait there's more....
-It can cause gastric distress: Eating more than just 35 grams can lead to stomach issues and a nutrient deficiency, especially amino acids which are extremely important.
-It can keep your body from absorbing proteins: Anti-nutrients have potent enzyme inhibitors that block the action of trypsin - enzyme needed for protein digestion. So will that just keep you from gaining muscle? No. Sure it will make it harder to build muscle, but do you know what other parts of you are made of protein? Well, to name a few: your skin, your hair, your bones, your teeth, and your nails…
-It can impact thyroid function: Soy contains goitrogens which are a substance that block the synthesis of your thyroid hormones and mess with iodine metabolism. This leads to lowering the thyroid function, this can lead to anxiety, digestive issues, weight gain, food allergies, and other problems. 
-It can mimic or block estrogen: Soybeans are rich in the compounds isoflavones, genistein, and daidzein - a type of phytoestrogen. These compounds resemble human estrogen, they disrupt endocrine function, and can have adverse effects on human tissues. Research and studies suggest that high levels of soy isoflavones can lead to infertility.  Did you know that the FDA is actually responsible for regulating any products containing estrogen?? But interestingly there are no warnings exhibited in soy foods...
-Soybean grown in the U.S. is genetically modified: Over 90% of the soybeans grown in the U.S. are genetically modified, making them GMO. They are engineered to survive to be heavily sprayed with chemical herbicides.  As you can imagine, this can have terrible effects on one's health.
Let's summarize everything
In order for soy to be considered a health food, it must be fermented so the anti-nutrients are reduced and you receive all the nutritional benefits. Try to purchase high-quality organic soy as opposed to the unfermented GMO soy. If you do choose to eat unfermented then keep your soy consumption below 35 grams!