Whether or not soy is healthy for you is a hotly debated issue. The debate stems largely from the fact that health benefits of fermented soy have been misconstrued as being applicable to nonfermented soy as well, which is simply not the case. 

How a Fact Became a Lie 

Fermented soybeans have been a tradition in Japanese cuisine for more than 1,000 years. The nutritive value of natto, for example, was so high that Samurai consumed it daily, and even fed it to their horses to increase their speed and strength.

Nonfermented soy products, on the other hand, are NOT health foods, even though manufacturers of soy products have been allowed to label them “heart healthy” since 1999. The “health benefits” of nonfermented soy were simply created through slick marketing by the edible oil industry in the US; invented to create a profitable market for the otherwise unusable byproducts of the soybean oil industry.

The deceptive heart health claim originated from the low rates of heart disease and certain cancers seen in East Asian populations. However, in reality, Asians do not consume nearly as much soy as has been generally assumed, and what they do eat has been fermented for long periods.

What’s Wrong With Nonfermented Soy?

Nonfermented soy products contain phytic acid, which has anti-nutritive properties. Phytic acid binds with certain nutrients, such as iron, to inhibit their absorption. This is a direct, physical effect that takes place in your digestive system. They’ve also been found to contain toxins and disruptive plant estrogens that can damage your thyroid. 

Most processed, nonfermented soy products also contain added flavorings, preservatives, sweeteners, emulsifiers and synthetic nutrients – a far cry from what you get after the traditional fermentation process that ancient cultures put their soy through before they would eat it. 

As a result of modern processing, most of today’s soy foods are chockfull of anti-nutrients that have been linked to:

• Malnutrition and digestive problems
• Thyroid dysfunction 
• Cognitive decline
• Reproductive disorders 
• Immune system breakdowns 
• Heart disease and cancer

It’s actually the fermenting process itself that turns an otherwise inedible food into something quite nutritious.  

Soy’s Health Benefits ONLY Apply to Fermented Soy!

As often as I’ve warned against nonfermented soy, such as fresh or dry whole soybeans, soy nuts, soy milk and tofu, I’ve also extolled the wonderful health benefits of traditionally fermented foods, and fermented soy is part of that pack.

After a long fermentation process, the phytic acid and antinutrient levels of the soybeans are reduced, and their beneficial properties – such as the creation of natural probiotics -- become available to your digestive system.

It also greatly reduces the levels of dangerous isoflavones, which are similar to estrogen in their chemical structure, and can interfere with the action of your own estrogen production.

So if you want to take advantage of the health benefits of soy, go ahead! Just make sure you’re eating the fermented varieties and avoid all nonfermented soy products.

Healthy options include:

• Natto, fermented soybeans with a sticky texture and strong, cheese-like flavor. It's loaded with nattokinase, a very powerful blood thinner.  
  
  Natto is actually a food I eat nearly every day as it is the highest source of vitamin K2 on the planet and has a very powerful beneficial bacteria, bacillus subtilis. It can usually be found in any Asian grocery store.

• Tempeh, a fermented soybean cake with a firm texture and nutty, mushroom-like flavor.

• Miso, a fermented soybean paste with a salty, buttery texture (commonly used in miso soup).

• Soy sauce: traditionally, soy sauce is made by fermenting soybeans, salt and enzymes, however be wary because many varieties on the market are made artificially using a chemical process.