Hello, yes indeed food plays a major part with psoriasis. I have battled it for 14 years trying every lotion and potion, then I read a book called Healing Psoriasis: The Natural Alternative, Pagano. Basically his theory: psoriasis is caused by too much acidic foods. Willing to try anything (it's on my hands and really embarrassing) I stopped eating red meat, pork, tomatoes, peppers, and a few other things that supposedly cause the body to be more toxic.
I also got a colonic (recommended to detox), a spinal adjustment, and did the apple cleanse for 3 days. It's been since September and you wouldn't even know that I have it unless you look very closely (slightly redder than the rest of my skin, but no scaly skin). I am shocked as I haven't seen a cream or ointment that has given me success like a simple change in my diet.
There has been a few occassions that I have ate beef or tomatoes, and my psoriasis will "flare up" for a day or two, but as long as I stay away from the "toxic" foods it usually calms down.
No creams or ointments; just a change in diet. Absolutely worth a try if you really want to rid yourself of such a horrible affliction!