Psoriasis is a common chronic skin disorder that affects over 4 million people. There is no cure for psoriasis and treatment is directed at controlling patients' symptoms. The purpose of this study is to determine whether psoriasis patients are more likely to have food sensitivities than those patients without psoriasis. We will also determine if eliminating certain foods from the diet results in a change in psoriasis symptoms.

Purpose: To determine the role of food sensitivity in psoriasis and assess the clinical response of an individualized elimination diet on psoriasis.

Design: Up to 50 volunteers with psoriasis and 20 age- and sex-matched controls will be recruited for a 12-week prospective correlational study.

Methods: Venous blood samples for the detection of antibodies against food antigens will be collected and individualized elimination diets will be designed based on the most reactive food antigens.

Assessments: Clinical assessments of objective and subjective parameters will be measured using Psoriasis Area and Severity Index (PASI), Static Physicians Global Assessment (sPGA), Dermatology Life Quality Index (DLQI), and Itch Numeric Rating Scale (Itch NRS).

Objectives: The primary objectives are to determine whether psoriasis patients are more likely to have food sensitivities and assess the clinical response of a 12-week elimination diet on psoriasis.

Inclusion criteria:

• Male or female subjects, 12 years of age or older.
• Good general health.
• Willingness and ability to follow the protocol.
• Signed Informed Consent Form, written and witnessed.
• Psoriatic group only: Chronic plaque psoriasis (patients must have diagnosis for at least 6 months) or guttate psoriasis involving 2 % or greater total body surface area or 2 plaques, each measuring > 8 cm2.
• Psoriatic group only: Psoriasis is untreated (as defined in Exclusion criteria 4) or subject has been on a stable topical or systemic treatment with no dose alteration or regimen alteration for >12 months.

Exclusion criteria:

• History of drug-induced psoriasis or pustular psoriasis.
• Moderate or severe psoriasis warranting systemic immunosuppression or inpatient admission.
• Pregnant, lactating, history of diabetes mellitus, thyroid disease or inflammatory bowel disease.
• Psoriatic group only: Use of biologic treatment for psoriasis within 3 months of baseline, use of systemic immunosuppressive treatment for psoriasis within 4 weeks of baseline, or use of topical treatment for psoriasis within 2 weeks.