Any time you add something new to your dog's diet, do so gradually. In the almost 3 years that I've had Pico I have collected a list of don'ts from vets regarding feeding:
Onions, raisins, grapes, chocolate, pork, turkey and broccoli.
Now Pico loves broccoli and I was giving it to him before hearing from several sources that it can be toxic. Other sources recommend broccoli. So the jury is out on that one.
I also give Pico avocado, red pepper, green beans, cauliflower and squash as well as egg and salmon. Always in pea-sized bites in limited amounts since he is eating commercial kibble and canned food as well. Some malts love baby carrots to chew on. Pico won't touch them. These little ones are as individual as humans. But far more lovable.