Hi, my new cat had terrible dandruff until I switched him to Dr. Pitcarin's natural diet. The diet includes raw meat grains and a little vegetable ( there is a whole bunch of recipes in the book) but I think the Healthy powder supplement is very important. Anyway in just three weeks he gleams- no dandruff.
In addition to diet, regular brushing the coat, to bring up flakes stuck near the skin, really helps.
It will look worse before it looks better because you are releasing the flakes buried in the fur.
It take a few times but brushing really helps.