Effect of climate therapy at Gran Canaria on vitamin D production, blood glucose and lipids in patients with psoriasis

Background Climate therapy (heliotherapy) of psoriasis is an effective and natural treatment. Ultraviolet radiation (UVB) from the sun improves psoriasis and induces vitamin D₃ synthesis. Objective The aim of the study was to investigate the effect of climate therapy on vitamin D₃ synthesis, blood glucose, lipids and vitamin B12 in psoriasis patients. Methods Twenty Caucasian patients (6 women and 14 men; mean age, 47.2 years; range, 24–65) with moderate to severe psoriasis [mean Psoriasis Area and Severity Index (PASI) score 9.8; range, 3.8–18.8] received climate therapy at the Gran Canarias for 3 weeks. Blood samples were drawn before and after 15 days of sun exposure. In addition, the patients’ individual skin UV doses based on UV measurements were estimated. Results Sun exposure for 15 days lead to a 72.8% (± 18.0 SD) reduction in the PASI score in psoriasis patients. Although no direct correlation was observed between PASI score improvement and UVB dose, the sun exposure improved the vitamin D, lipid and carbohydrate status of the patients. The serum concentrations of 25‐hydroxyvitamin D [25(OH)D] increased from 57.2 ± 14.9 nmol/L before therapy to 104.5 ± 15.8 nmol/L (P < 0.0001) after 15 days of sun exposure; the serum levels of 1,25‐dihydroxyvitamin D [1,25(OH)₂D] increased from 146.5 ± 42.0 to 182.7 ± 59.1 pmol/L (P = 0.01); the ratio of low‐density lipoprotein cholesterol and high‐density lipoprotein cholesterol decreased from 2.4 to 1.9 (P < 0.001); and the haemoglobin A₁c (HbA₁c) levels decreased from 5.6 ± 1.7% to 5.1 ± 0.3% (P < 0.0001). Conclusion Climate therapy with sun exposure had a positive effect on psoriasis, vitamin D production, lipid and carbohydrate status.