Background Psoriasis is a systemic inflammatory disease characterized by hindered antioxidant defense and increased formation of free radicals. There are limited data on the skin carotenoids in psoriatic skin as well as their modulation during narrow‐band UVB (NB‐UVB) phototherapy of the disease. Aim The aim of this prospective study is to reveal the skin carotenoids levels during NB‐UVB phototherapy of psoriasis in humans. Material and methods Twenty Caucasian subjects with mild‐to‐moderate plaque psoriasis (15m; 5f) were enrolled in the study, and nine gender‐ and age‐matched healthy volunteers were recruited for controls of oxidative stress measurements. All psoriasis patients underwent 10 sessions of NB‐UVB phototherapy. Measurements were taken at baseline and after 10 sessions of NB‐UVB phototherapy. The assessment of carotenoid levels in the skin in vivo was performed by a non‐invasive, reflectance spectroscopy‐based device. Psoriasis severity was assessed by psoriasis area and severity index (PASI). The dermatology life quality index (DLQI) was evaluated in psoriatic patients. Results Baseline carotenoid levels were significantly lower in psoriasis patients in comparison to healthy controls. NB‐UVB phototherapy insignificantly diminished carotenoid levels in the skin of psoriasis patients, while clinical improvement both in PASI score and DLQI was observed. Conclusion We showed the levels of skin carotenoids in psoriatic patients are lower than in healthy subjects. NB‐UVB did not change significantly skin carotenoid levels. Further studies should elucidate the potential effect of antioxidants supplementation during NB‐UVB of psoriasis.

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