Impact of the Mediterranean Diet on Patients with Psoriasis

The goal of this clinical trial is to determine the effect of a high-intensity Mediterranean diet intervention over 16 weeks in a group of patients with mild to moderate psoriasis in terms of skin improvement as measured by PASI. In addition, the aim of this study will be to gather the necessary information for a larger and more extended clinical trial in the future.

Participants will be provided with dietary education for the implementation of the Mediterranean diet, supported by a monthly follow-up by nutritionists with experience in the field. Researchers will compare the effect of the Mediterranean diet on these patients to a control group provided with standard recommendations for a low-fat diet with no monitoring by nutritionists.

MEDIPSO is an experimental, randomised, controlled, open-label, single-blinded (evaluator) study. It is a clinical trial in which patients with mild to moderate psoriasis with stable topical treatment are randomly assigned to either the control group or the intervention group. Patients assigned to the intervention group will undergo dietary education for the adoption of the Mediterranean diet, with monthly monitoring - mostly online - by nutritionists with experience in the field. In both groups, blood tests with metabolic parameters will be obtained before and after the study period, and data of anthropometric characteristics and quality of life will be assessed. The effect of the intervention on skin involvement, metabolic parameters and inflammatory cytokines will be assessed, and the emotional and quality of life impact will also be investigated. In addition, a methodological analysis will be carried out in order to improve the design for a larger scale clinical trial in the future.

Eligibility Criteria:
Inclusion Criteria:

* Psoriasis clinically diagnosed by a dermatologist.
* Predominantly psoriasis vulgaris.
* Psoriasis Area and Severity Index (PASI) ≥2 and ≤ 10 at the time of recruitment.
* Stable weight (\< 5% weight loss or gain) in the last 3 months.
* Treated exclusively with topical treatment for psoriasis at enrolment and throughout the study.
* Able to give informed consent.
* Willing and able to follow the study procedure.
* Willing and able to attend all scheduled visits during the study period.
* Willing and able to provide blood samples as indicated in the procedure.
* Willing to implement pregnancy prevention measures throughout the study period.

Exclusion Criteria:

* Type 1 or 2 diabetes mellitus.
* Good adherence to the Mediterranean diet at the time of screening (er-MEDAS ≥8).
* Language barrier (patients not fluent in Spanish or English).
* Conditions that make telephone communication difficult (e.g. severe hearing loss).
* History of cardiac disease(s).
* Comorbidities that may compromise the implementation of the intervention (e.g. cancer, digestive diseases...) or limit survival to less than 6 months.
* History or current eating disorder (anorexia, bulimia, etc.; screening will be carried out using the Diagnostic and Statistical Manual of Mental Disorders, fifth edition, if indicated).
* Malnourished patients (screening using the Malnutrition Universal Screening Tool -MUST-, if indicated).
* Presenting gout.
* Pregnant, planning pregnancy or breastfeeding.
* Use of diuretics at the time of sampling.
* BMI greater than 40 kg/m2.
* Difficulty or inconvenience in changing dietary habits and following the Mediterranean diet (allergies, food intolerances, special diets).
* Participation in a clinical trial with drugs or dietary intervention in the year prior to inclusion in this study.
* Patients who during the recruitment period are expected to have poor collaboration, lack of commitment or real difficulties in following the development of the study.