What ingredients should I avoid in dog food to prevent allergies and digestive problems in my sensitive dog?

[George Petter]

My dog has a very sensitive stomach and seems to react poorly to certain foods. I want to understand which ingredients are commonly associated with allergies and digestive problems in dogs so I can avoid them. For example, are there specific grains, proteins, or additives that are known to cause issues? Any advice on how to read and understand dog food labels would also be greatly appreciated.