I think there is a lot of truth to this. Right now, my kitties seem to all be able to eat the same food and are fine.

But some years ago, when we had two female kitties, Crystal and Lucy, Crystal loved to eat raw liver. Lucy wouldn't touch it. I think that it is possible that Crystal had a vitamin deficiency that the liver corrected. She also loved brewer's yeast tablets, which I heard were good for repelling fleas. Don't know if this is true or not, but Crystal was allergic to flea bites (she would just mow off her fur the poor thing) and she loved the brewer's yeast.

I also heard that we humans, at least as babies, will gravitate towards the foods that we need. I think we can discover our own vitamin deficiencies if we listen to ourselves enough.