I fed my effected omega 3 fish oils and they had good diets.It made me feel good , but it didn't really hold down the flakes.
I posted on another threads on this subject what I purchased and used topically. I hated shampooing all the time so I used the topical stuff. it made them smell great and it seemed to work because from what I understand this flakiness is an outer layer dermis ? The more you brush and fuss with the coat the more you aggrevated the coat.
Like I said before.........I think that effected dogs have different degrees of flakiness.