Protein bar ingredients like soy lecithin or soy protein isolate may add to the protein count, but may not be so good for you. Registered dietitian Lauren Slayton even described them as “seriously processed soy junk” (via Anytime Fitness).
During the processing of protein isolates, some of the nutrients found in plant proteins like seeds, nuts, and legumes are stripped, according to the T. Colin Campbell Center for Nutritional Studies. Your protein bar may therefore lose some of the fiber, essential fatty acids, vitamins and minerals, and other phytonutrients found in whole food plant protein sources. So, you don’t get the full benefits of the whole-food protein source. Furthermore, it won’t have the synergistic properties of nutrients that a whole-food source can provide.
Concerns surrounding soy lecithin include possible allergic reactions in those with a soy allergy (that is, if the amount is sufficient), according to Wholier. Furthermore, it may have the potential to disrupt hormonal balance, critics say. That’s because phytoestrogens in soy may mimic the estrogens in our bodies. There’s also the genetic modification (GM) concern: soy lecithin is often derived from GM soybeans. And while the jury is still out on this, an additive is not exactly the most optimal way to obtain protein.