"Natural Balance" and allergies in a lab

[alex_v]

Hello,
I have a 6 years chocolate lab, who’s prone to food allergies (pork, lamb, wheat and so on). For 4 years I've been feeding him "Natural Balance" Allergy line food: Potato and Duck first, then Venison and Green Pea, and now Sweet Potato and Fish. During the time he gets used to the food and developed allergy (mostly scratching and ear infection).
Questions: is Natural Balance good quality food and what do I need to feed him to reduce the allergies?
Thanks
Alex