Is there any downside to consuming soy protein?

No, there is no downside to consuming soy protein as part of a balanced diet. Soy is one of the oldest foods known to humankind, and has been a staple of Asian diets for centuries.

On the other hand, an upside to using soy protein is that a claim has been approved through the FDA in America that "25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease".