Circadian Oscillations of Minimal Erythema Dose (MED) are Also Influenced by Diet in Patients with Psoriasis: A Chronomedical Study

Abstract Introduction Minimal erythema dose (MED) remains a parameter of paramount importance to orient narrow-band (NB)-UVB phototherapy in psoriatic (PsO) patients. Recently, circadian rhythm and diet were recognized as potential MED modulators, but their mutual interaction remains understudied. Thus, we aimed to evaluate the potential diet modulation of MED circadian oscillations. Methods In the first phase, a cohort study was performed comparing potential MED oscillations (morning, afternoon, and evening) among omnivorous psoriatic patients before and after a phototherapy cycle and omnivorous healthy controls. The two groups were age-, gender-, skin-type-, MED-, and diet-matched. Then, in the second phase, another cohort study was carried out comparing MED oscillations 24 h after the last phototherapeutic session only in psoriatic patients cleared with NB-UVB and undergoing different diets (vegan, vegetarian, paleo , ketogenic, intermittent circadian fasting, and omnivore). Patients with different diets were age-, gender-, and skin-type matched. Results In the first phase, we enrolled only omnivores, specifically 54 PsO patients and 54 healthy individuals. Their MED before and after NB-UVB therapy changed significantly among the three different time-points (morning, afternoon, and evening) (p