flea allergy

Question
Hey,  I am looking to find out some information about brewers yeast in my dogs food.  The one is allergic to flea bites. And the puppy has a few.  But every time I put a topical on i feel like it never works.  I work at petsmart so i have an idea of stuff to use and I also go to school to become a dog trainer.  He is on medicine now.  But tell me about brewers yeast, is it worth trying?  Well it deter them? Any other suggestions? What about dinovite?
Thanks so much.

P.s.  baths every other day is out of the question.

Answer
Brewer's yeast will not work to combat fleas.  Long ago it was thought that the vitamin called thiamine (vitamin B-1) would repel fleas because it does seem to have some insect repellant activity in people. Scientific clinical trials did not show any benefit to feeding any
brewers yeast product in repelling or killing fleas. The difference between people and dogs is that we sweat and that's where the B-1 can come out onto the skin.  Dogs do not sweat except on their feet and the skin below their nose.

I've been battling fleas in my dog and cat practice for over 35 years and the absolute best thing to kill fleas quickly in dogs that are allergic to flea bites is an oral medication called spinosad (Comfortis).