How to Provide Adequate UV Dosimetry to Avoid Vitamin D Deficiency and Related Neuropsychiatric Disorders

The essential role of vitamin D3 in maintaining calcium metabolism and other physiological processes in the body (modulation cell growth, neuromuscular conduction, immunity and inflammation) is well established. In recent studies vitamin D3 is considered as one of the neurosteroids that are required for the brain to develop and function properly. Vitamin D3 is synthesized in human skin from 7-Dehydrocholesterol (provitamin D3) upon solar UVB (280–315 nm) irradiation which is very variable depending on latitude, season, air pollution, etc. A high incidence of vitamin D deficiency in almost all populations in the world was detected in the last decade by epidemiologic studies that may cause a number of chronic diseases (cancer, multiple sclerosis, etc.). This indicates the need to measure precisely the vitamin D synthesizing capacity of sunlight (as well as artificial UV sources) to maintain optimal vitamin D status. For this purpose, a bioequivalent UV ‘VitaD’-biodosimeter has been developed which is based on the same photoreaction in vitro by which vitamin D3 is synthesized in human skin.

Keywords: UV radiation; UV bioeffects; Erythema; Provitamin D photoconversion; Vitamin D deficiency; UV biodosimeter

Abbreviations: UV: Ultraviolet; 7-DHC – 7: Dehydrocholesterol Provitamin D3; 1,25(OH)2D: 1,25- Dihydroxyvitamin D (calcitriol); 25(OH)D: 25- Hydroxyvitamin D (calcidiol); IU: International Unit for Vitamin D3 (1 IU = 40 mcg); CIE: International Commission on Illumination (Commission Internationale de L’Eclairage); MED: Minimal Erythemal Dose; LC: Liquid Crystal; SED: Standard Erythemal Dose