The present invention provides engineered amylase polypeptides and compositions thereof. The engineered amylase polypeptides have been optimized to provide improved thermostability, protease stability, and stability under a range of pH conditions, including acidic (pH<7) conditions. The invention also relates to the use of the compositions comprising the engineered amylase polypeptides for therapeutic and/or nutritional purposes. The present invention also provides polynucleotides encoding the engineered amylase polypeptides, as well as methods for making the engineered polynucleotides and amylase polypeptides.