I occassionally get really dry and flaky lips although I hadn't linked it to nutrition but I think you may be on to something.A while ago I stopped taking my essential fatty acids and I suddenly had very bad attack of flaky lips which I hadn't had for ages.
Part of my usual nutritional regime is to take essential fatty acids and I take either hemp seed oil(omegas 3, 6 & 9) or emu oil(omegas 3, 6 & 9), both of which don't give you that fishy taste.
To topically treat the flaky lips I use jojoba oil. I massage it in gently before I wash my face as it helps to loosen and moisturize the dead skin, which usually flakes off during the course of wiping my face gently with a flannel. To protect my lips for the rest of the day I use a beeswax based lipbalm with added propolis. As another person who replied to this post mentioned, I also try to avoid petroleum based products for environmental and health reasons. The beeswax protects but also lets your skin breathe, unlike vaseline type products and the lipbalm I use has the added healing properties of propolis.