Psoriasis is an immune system mediated skin disease which can be brought into remission by certain medications and life style changes. Now it is well established and believed to be a multi system disorder involving joints, hearts and kidneys as well. A proper assessment to determine the severity of psoriasis and an assessment of other organ involvements is needed. Most of the patients do well if they stick to the recommendations. Kindly see a dermatologist for a treatment plan. You can apply.
Regarding diet, it is helpful but in a indirect way. Kindly follow this link https://www.psoriasis.org/about-psoriasis/treatments/alternative/diet-supplements