Similac Isomil Advance Soy 12 9 oz Powder The Isomil Advance Soy 12 9 oz Powder is another great formula from Similac It is the best formula for common feeding problems A newborns digestive system is delicate and may need time to fully develop This Similac Formula will take care of common feeding problems because of the delicate nature of the system Similac Isomil can take care of a fussy baby with gas or spit up If baby has common feeding problems continue with the Similac Formula as switiching formulas can have adverse effecs on the childs system If common feeding problems continue then ask the doctor about switching to a different Similac Formula