Though this secret is often overlooked in the West, Asians have known for centuries that soy protein powder is an excellent supplement for nutrition, as well as being of great medicinal value. Soy protein powder only came to use in the United Stated in the early nineteenth century, and since it was at the time based on soy flour, it sometimes caused gastrointestinal distress. Decades passed before a method was used to reduce these unpleasant side effects via soy protein isolate.