Should You Avoid Soy Protein Isolate?

 Turn over many a nutrition bar or box of veggie burgers, and you'll often find soy protein isolate (SPI) featured prominently on the ingredient list. But what is soy protein isolate? Is non GMO soy protein good? And what are the chemicals used to make soy protein?

While there's disagreement among nutritionists over whether soy is part of a healthy diet (some are concerned about its estrogenic properties but others like it as protein source that's an alternative to meat), most agree that SPI, its super-processed offspring, should be avoided. 

"A big issue with soy is that we're eating more of it than ever before and in very processed forms like SPI."  So SPI may have started out as a plant, but once it gets to you, it's far from it. 

Soy isolate protein is missing a lot of nutrients

"Soybeans are a great quality protein because their amino acid content is similar to that in meat, and they're a good source of fiber, minerals, and complex carbs."  But to create SPI, soybeans are chemically engineered to "isolate" their protein, and this process strips out all of the other nutrients the original bean contained. 

Soy isolate protein is probably genetically modified

According to the USDA, over 90 percent of the soybeans grown in the U.S. are genetically modified, so most SPI comes from altered beans. "This means soy protein isolate is chemically modified, processed, and filled with pesticides." 

It may upset your stomach

Many people have allergies or intolerances that make it hard to digest soy. But even if you're not one of them, soy protein isolate may make your stomach rumble. This is because SPI has a higher concentration of trypsin inhibitors, chemicals that reduce available trypsin—an enzyme that helps digest protein—in the body. 

So what to do if you're a soy-loving vegetarian? Skip products with SPI and opt for "natural, whole protein sources like beans, lentils, nuts, and seeds, and organic, non-GMO natural sources of soy like edamame, tofu, and tempeh."