I don't think feeding him or her anything will help with fleas. The best thing I've found for fleas on a cat or a dog is Frontline or Advantage. I don't think food works.
Brewer's yeast with garlic is a very good thing to help get rid of fleas. It comes in a chewable pill form that dogs will usually eat just like a treat.
There isn't really any type of food out there that will get rid of fleas. You need to buy a product used to treat the fleas. Once the dog is treated be sure to treat the surrounding areas as well.
